RULES FOR CLASSIFICATION Offshore units · FOREWORD DNV GL rules for classification contain procedural and technical requirements related to obtaining and retaining a class certificate

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DNV GL AS

RULES FOR CLASSIFICATION

Offshore units

DNVGL-RU-OU-0104 Edition April 2016

Self-elevating units

FOREWORD

DNV GL rules for classification contain procedural and technical requirements related to obtainingand retaining a class certificate. The rules represent all requirements adopted by the Society asbasis for classification.

© DNV GL AS April 2016

Any comments may be sent by e-mail to [email protected]

If any person suffers loss or damage which is proved to have been caused by any negligent act or omission of DNV GL, then DNV GL shallpay compensation to such person for his proved direct loss or damage. However, the compensation shall not exceed an amount equal to tentimes the fee charged for the service in question, provided that the maximum compensation shall never exceed USD 2 million.

In this provision "DNV GL" shall mean DNV GL AS, its direct and indirect owners as well as all its affiliates, subsidiaries, directors, officers,employees, agents and any other acting on behalf of DNV GL.

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Rules for classification: Offshore units — DNVGL-RU-OU-0104. Edition April 2016 Page 3Self-elevating units

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CHANGES – CURRENT

This document supersedes DNVGL-RU-OU-0104, July 2015.Changes in this document are highlighted in red colour. However, if the changes involve a whole chapter,section or sub-section, normally only the title will be in red colour.

Main change April 2016, entering into force 1 October 2016• General— Clarification of the status of (top-side) modules and other subcontracted parts for new builts from a class

service point of view— Clarification that worldwide service operation not is applicable for self-elevating units.— Updated requirement for steel grade selection— Further development of the unit specific In-service Inspection program, defining three levels with

possibilities of further inspection scope depending on available documentation/ performed analysis— Correction of some minor issues improving efficiency and quality of iO-surveys— Further clarified the class requirements for bottom surveys.— Including new notation RENEW for follow-up on (mid-life) upgrades— Updates to keep the document in line with other rule and standard changes.

• Ch.1 Sec.1— Table 2: Updated definition on CMC with new guidance note.

• Ch.2 Sec.1 Introduction— Table 1: updated to include new notations RENEW and Crane-offshore replacing the former Crane

notation.

• Ch.2 Sec.2 Procedures— [2]: Included new guidance note to clarifying limited scope of CMC.

• Ch.2 Sec.3 Principles and condition— [3.1]: New clause clarifying that worldwide service operation not is applicable for self-elevating units.

• Ch.4 Sec.1 Hull and equipment— [3.2]: Updated latest paragraph on required design life.— [4.2]: Updated guidance note on wind velocity.— [6.1]: Included new guidance notes.— [6.2]: Updated clause on material selection.— [7.4]: Updated clause by summarising original content.

• Ch.6 Sec.1 Procedures— [1]: Included new guidance note to clarifying limited scope of CMC.

• Ch.8 Sec.3 Preparation and planning— [2.2]: Sub-section rewritten.— Updated Table 3.

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• Ch.8 Sec.4— [1]: New sub-section clarifying scope of annual survey.— [1.2]: Completed descriptions on structural survey with specific focus on protective coating and thickness

measurements— [1.3.7]: Updated listing of items under survey.— [1.4]: Included new guidance note.— [2.1.2]: Updated clause with new item in listing.— [2.1.4]: New clause refering to lower leg and spudcan survey.— [3.2.3] and [3.2.4]: Added new clauses.— [3.2.5] and [3.2.6]: Updated clauses and moved former Table 5 to guidance note.— [3.2.7] Moved former Table 6 to guidance note.

• Ch.8 Sec.5— [2]: Section re-written. Bottom survey split between MODU req. and main class survey req.— [3]: Section re-written to split between MODU req. and main class survey requirements.— [5]: New sub-section completing overview of additionial surveys.

• Ch.8 Sec.6— Complete new section describing the new RENEW class notation.

Editorial corrections

In addition to the above stated changes, editorial corrections may have been made.

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CONTENTS

Changes – current............................................................3

Chapter 1 Introduction................................................... 14Section 1 Introduction....................................................................................................... 14

1 General...............................................................................................................14

2 Objective............................................................................................................ 14

3 Scope................................................................................................................. 14

4 Structure............................................................................................................ 14

5 Definitions..........................................................................................................15

5.1 Verbal forms...................................................................................................15

5.2 Definitions...................................................................................................... 15

5.3 Abbreviations.................................................................................................. 19

Chapter 2 General regulations and conditions................ 20Section 1 Classification principles..................................................................................... 20

1 General...............................................................................................................20

2 Application......................................................................................................... 20

2.1 Interpretations................................................................................................ 20

3 Class scope and notations................................................................................. 21

3.1 Scope............................................................................................................ 21

3.2 Notations........................................................................................................21

Section 2 Procedures......................................................................................................... 22

1 Plan approval..................................................................................................... 22

1.1 Format........................................................................................................... 22

1.2 Subcontractors................................................................................................ 22

1.3 Plans and data to be submitted........................................................................ 22

2 Certification........................................................................................................22

3 Testing and surveys...........................................................................................22

Section 3 Principles and conditions................................................................................... 24

1 General...............................................................................................................24

2 Design principles................................................................................................24

2.1 Scope............................................................................................................ 24

2.2 Safety and important systems.......................................................................... 24

2.3 Redundancy.................................................................................................... 25

2.4 Failure effects................................................................................................. 25

3 Environmental conditions...................................................................................26

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3.1 Principles........................................................................................................26

3.2 Design temperature......................................................................................... 26

3.3 Temperature for machinery systems and equipment............................................ 26

3.4 Cooling water temperatures..............................................................................27

3.5 Humidity........................................................................................................ 27

3.6 Performance................................................................................................... 27

3.7 Inclinations..................................................................................................... 27

3.8 Vibrations....................................................................................................... 28

Chapter 3 Materials and welding.................................... 29Section 1 Metallic materials...............................................................................................29

1 General...............................................................................................................29

2 Principles........................................................................................................... 29

Section 2 Structural fabrication.........................................................................................31

1 General...............................................................................................................31

2 Plans and data to be submitted.........................................................................31

Chapter 4 Hull and equipment........................................ 32Section 1 Structural design............................................................................................... 32

1 General...............................................................................................................32

1.1 Introduction....................................................................................................32

1.2 Scope............................................................................................................ 32


2 Principles........................................................................................................... 35

3 Analysis and calculations................................................................................... 36

3.1 General.......................................................................................................... 36

3.2 Fatigue analysis.............................................................................................. 36

4 Design and loading conditions........................................................................... 36

4.1 General.......................................................................................................... 36

4.2 Environmental conditions..................................................................................37

5 Loads and load effects.......................................................................................38

5.1 General.......................................................................................................... 38

5.2 Accidental loads.............................................................................................. 38

6 Structural categorization, material and inspection principles.............................39

6.1 Structural categorization.................................................................................. 39

6.2 Material selection............................................................................................ 39

7 Structural strength.............................................................................................40

7.1 General.......................................................................................................... 40

7.2 Footing strength..............................................................................................40

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7.3 Section scantlings............................................................................................41

7.4 Fatigue strength..............................................................................................41

8 Weld connections...............................................................................................42

9 Corrosion control............................................................................................... 42

Section 2 Stability and watertight integrity.......................................................................43

1 General...............................................................................................................43

1.1 Introduction....................................................................................................43


2 Stability..............................................................................................................44

3 Watertight integrity, freeboard and weathertight closing appliances.................45

3.1 General.......................................................................................................... 45

3.2 Materials........................................................................................................ 45

3.3 Watertight integrity......................................................................................... 45

3.4 Weathertight closing appliances........................................................................ 46

3.5 Freeboard.......................................................................................................47

3.6 Penetrations....................................................................................................47

Section 3 Towing............................................................................................................... 48

1 General...............................................................................................................48

1.1 Introduction....................................................................................................48


1.3 Principles........................................................................................................48

2 Detailed requirements........................................................................................48

2.1 General.......................................................................................................... 48

2.2 Material..........................................................................................................49

2.3 Strength analysis............................................................................................ 49

Chapter 5 Machinery systems and equipment.................51Section 1 Marine, machinery and piping systems..............................................................51

1 General...............................................................................................................51

1.1 Introduction....................................................................................................51

1.2 Application......................................................................................................51


2 Principles........................................................................................................... 53

2.1 General.......................................................................................................... 53

2.2 Component design...........................................................................................54

3 Valves.................................................................................................................54

3.1 Design and tests............................................................................................. 54

3.2 Installation..................................................................................................... 54

3.3 Operation....................................................................................................... 54

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4 Piping................................................................................................................. 54

4.1 Design........................................................................................................... 54

4.2 Materials........................................................................................................ 55

4.3 Platform piping............................................................................................... 56

4.4 Machinery piping............................................................................................. 57

4.5 Pipe fabrication, workmanship and testing..........................................................59

5 Rotating machines............................................................................................. 59

5.1 Principles........................................................................................................59

5.2 Diesel engines................................................................................................ 60

5.3 Starting arrangements..................................................................................... 60

5.4 Start from “dead ship”.....................................................................................61

6 Jacking system...................................................................................................62

6.1 General.......................................................................................................... 62

6.2 Design principles............................................................................................. 62

6.3 Materials........................................................................................................ 63

6.4 Arrangement...................................................................................................63

6.5 Electrical systems............................................................................................63

6.6 Control and monitoring.................................................................................... 63

6.7 Testing and inspection..................................................................................... 64

Section 2 Electrical installations........................................................................................65

1 General...............................................................................................................65

1.1 Introduction....................................................................................................65

1.2 Application......................................................................................................65


2 Principles........................................................................................................... 66

3 Arrangements and installation...........................................................................67

3.1 Arrangement...................................................................................................67

3.2 Installation..................................................................................................... 67

4 Power supply..................................................................................................... 68

4.1 Main.............................................................................................................. 68

4.2 Emergency power supply systems..................................................................... 69

4.3 Battery systems.............................................................................................. 70

4.4 Power supply to jacking gear............................................................................70

5 Electrical power distribution.............................................................................. 70

6 Protection...........................................................................................................71

7 Control............................................................................................................... 71

8 Electrical equipment:......................................................................................... 72

9 Cables.................................................................................................................73

9.1 Cable selection................................................................................................73

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9.2 Cable construction and rating........................................................................... 73

9.3 Cable routing and installations..........................................................................73

Section 3 Area arrangements............................................................................................ 75

1 General...............................................................................................................75

1.1 Scope............................................................................................................ 75


2 Divisions and equipment location...................................................................... 75

2.1 General.......................................................................................................... 75

2.2 Electrical installations.......................................................................................76

3 Hazardous areas................................................................................................ 77

3.1 Area classification............................................................................................77

3.2 Battery rooms, paint stores, and welding gas bottle stores................................... 77

3.3 Requirements for specific systems.....................................................................77

4 Ventilation systems............................................................................................78

5 Marking and signboards.....................................................................................78

Section 4 Control and communication systems and emergency shutdown........................ 81

1 General...............................................................................................................81

1.1 Introduction....................................................................................................81

1.2 Application......................................................................................................81


2 Principles........................................................................................................... 82

2.1 General.......................................................................................................... 82

2.2 Response to failures........................................................................................ 82

3 System design....................................................................................................82

4 Component design and installation....................................................................83

5 User interface.................................................................................................... 83

6 ESD and emergency control...............................................................................84

6.1 Emergency shut down..................................................................................... 84

6.2 Emergency control...........................................................................................87

7 Communication and alarms................................................................................88

7.1 Communication............................................................................................... 88

7.2 Alarms........................................................................................................... 88

Section 5 Fire protection................................................................................................... 90

1 General...............................................................................................................90

1.1 Introduction....................................................................................................90

1.2 Application......................................................................................................90


2 Principles........................................................................................................... 91

3 Passive fire protection....................................................................................... 92

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4 Fire fighting systems......................................................................................... 92

4.1 Fire pumps, fire mains, hydrants and hoses....................................................... 92

4.2 Active fire protection of specific areas............................................................... 92

4.3 Fire fighting systems of specific types............................................................... 93

5 Fire and gas detection systems......................................................................... 93

6 Escape................................................................................................................94

Section 6 Enhanced systems............................................................................................. 95

1 Introduction....................................................................................................... 95

1.1 General.......................................................................................................... 95

1.2 Objective........................................................................................................95

1.3 Scope............................................................................................................ 95

1.4 Application......................................................................................................95

1.5 Documentation requirements............................................................................ 95

2 Technical requirements......................................................................................95

3 Certification of materials and components.........................................................96

Chapter 6 Certification....................................................97Section 1 Procedures......................................................................................................... 97

1 Introduction....................................................................................................... 97

2 Certification types..............................................................................................97

3 Class involvement.............................................................................................. 98

4 Certification in operation................................................................................... 98

Section 2 Machinery and system certification................................................................... 99

1 General...............................................................................................................99

2 Principles........................................................................................................... 99

3 Machinery systems and equipment.................................................................. 100

3.1 General........................................................................................................ 100

3.2 Miscellaneous mechanical components............................................................. 101

3.3 Pressure vessels............................................................................................101

3.4 Main and emergency power............................................................................ 102

3.5 Jacking machinery......................................................................................... 103

3.6 Components in marine and machinery piping systems........................................103

4 Electrical installations...................................................................................... 104

5 Automation and control system....................................................................... 107

6 Fire protection................................................................................................. 107

7 Watertight/ weathertight integrity.................................................................. 108

Chapter 7 Newbuilding survey...................................... 110Section 1 Introduction..................................................................................................... 110

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1 Overview.......................................................................................................... 110

2 Structure.......................................................................................................... 110

3 Principles..........................................................................................................110

Section 2 Survey planning............................................................................................... 112

1 Objective.......................................................................................................... 112

2 Scope............................................................................................................... 112

3 Quality survey plan..........................................................................................112

3.1 Introduction.................................................................................................. 112

3.2 Review of the construction facility................................................................... 112

3.3 New building survey planning......................................................................... 112

Section 3 Fabrication of structures..................................................................................114

1 Principles..........................................................................................................114

2 Technical provisions.........................................................................................114

3 Certification and classification......................................................................... 114

Section 4 Commissioning process....................................................................................115

1 Introduction..................................................................................................... 115

2 Principles..........................................................................................................115

3 Process.............................................................................................................115

4 Survey scope categories.................................................................................. 115

5 Test requirements related to marine, utility and safety systems......................116

6 Jacking trials....................................................................................................116

Section 5 Deliverables..................................................................................................... 117

1 Class certificate................................................................................................117

2 Conditions of class...........................................................................................117

3 Appendix to class certificate............................................................................117

4 Additional declarations.....................................................................................117

5 Statutory certificates....................................................................................... 117

Chapter 8 Classification in operation............................ 119Section 1 Introduction..................................................................................................... 119

1 Introduction..................................................................................................... 119

2 Objective.......................................................................................................... 119

3 Scope............................................................................................................... 119

Section 2 General provisions and requirements for surveys............................................120

1 Conditions for retention of class......................................................................120

2 Class involvement............................................................................................ 120

2.1 General........................................................................................................ 120

2.2 Damage and repairs...................................................................................... 120

2.3 Temporary equipment.................................................................................... 121

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3 Special provisions for ageing units.................................................................. 121

3.1 General........................................................................................................ 121

3.2 Corrosion measurements and condition of protective coating...............................121

3.3 Fatigue utilization index..................................................................................121

3.4 Follow up for FUI bigger than one................................................................... 122

3.5 Additional inspections.....................................................................................123

4 Alternative survey arrangements.....................................................................123

5 Surveys performed by approved companies.....................................................123

Section 3 Preparation and planning.................................................................................125

1 Preparation...................................................................................................... 125

2 Planning........................................................................................................... 125

2.1 General........................................................................................................ 125

2.2 In-service inspection program (IIP)................................................................. 126

Section 4 Periodical surveys............................................................................................130

1 Annual survey.................................................................................................. 130

1.1 Scope...........................................................................................................130

1.2 Structure and equipment................................................................................130

1.3 Machinery and safety systems........................................................................ 133

1.4 Documentation.............................................................................................. 135

2 Intermediate survey........................................................................................ 136


2.2 Machinery and systems.................................................................................. 136

3 Renewal survey................................................................................................137

3.1 Extent.......................................................................................................... 137


3.3 Machinery and systems.................................................................................. 142

3.4 General........................................................................................................ 145

Section 5 Other surveys.................................................................................................. 146

1 General.............................................................................................................146

2 Bottom survey..................................................................................................146

2.1 General........................................................................................................ 146

2.2 Scope...........................................................................................................146

3 Spudcan and leg survey...................................................................................146

3.1 General........................................................................................................ 146

3.2 Scope...........................................................................................................147

3.3 Intermediate survey.......................................................................................147

3.4 Renewal survey............................................................................................. 147

4 Survey after ocean transit............................................................................... 147

5 Surveys in relation to permanent installation.................................................. 148

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Section 6 Upgrades..........................................................................................................149

1 Introduction..................................................................................................... 149

1.1 General........................................................................................................ 149

1.2 Objective...................................................................................................... 149

1.3 Scope...........................................................................................................149

1.4 Application.................................................................................................... 149

1.5 Documentation requirements.......................................................................... 150

2 Structure.......................................................................................................... 150

2.1 Survey......................................................................................................... 150

2.2 Ultimate limit state........................................................................................151

2.3 Fatigue limit state......................................................................................... 151

2.4 Corrosion......................................................................................................151

3 Systems............................................................................................................152

3.1 Survey......................................................................................................... 152

3.2 Safety systems..............................................................................................152

3.3 Jacking systems............................................................................................ 152

3.4 Additional systems.........................................................................................153

4 Retention..........................................................................................................153

Section 7 Permanently installed self-elevating units....................................................... 154

1 Introduction..................................................................................................... 154

2 Fatigue............................................................................................................. 154

3 Inspection and maintenance............................................................................154

3.1 Facilities for survey........................................................................................154

3.2 Surveys........................................................................................................ 154

3.3 Inspection before re-location...........................................................................154

Changes - historic........................................................ 155

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CHAPTER 1 INTRODUCTION

SECTION 1 INTRODUCTION

1 GeneralThe classification rules for design and construction of self-elevating units can be found in the applicablerequirements of DNV GL offshore standards and service descriptions. Recognizing that these are genericin nature, both in the topics covered and in the actual requirement description, there is an opportunity toconstruct an abstract of these with a focus on self-elevating unit relevant requirements.

2 ObjectiveThe objective of this publication is to give a complete but concise overview of the relevant technicalstandards and DNV GL’s involvement for building and classing a conventional self-elevating unit. In thisobjective, the book is to be used in conjunction with DNVGL-RU-OU-0101 Rules for classification of drillingand support units and the relevant technical standards as referred to therein.

3 ScopeThis publication describes the technical and procedural requirements for classification of self-elevating unitsof a conventional design as covered by main class. Both the description of a conventional design and thescope of main class is further detailed in Ch.2.This publication covers the involvement of class for a unit’s different phases during life time, i.e. design,construction, commissioning, delivery and operation.The publication does not cover the requirements for separate additional class notations, nor the requirementsfor units of an unconventional design. These are detailed in DNVGL-RU-OU-0101.This publication does not cover the requirements applicable for units drilling on a fixed platform.

4 StructureTo maintain a clear overview, these rules consist of references to the relevant rules offshore standardsand other DNV GL service documents. The degree of reference detail is depending on the nature of thesubject. To improve readability and understanding, the references are completed with a direct description ofrequirements. In special, a description has been included on topics of a higher complexity or risk.The second chapter of these rules describes the principles of classification and its procedures in Ch.2 Sec.1and Ch.2 Sec.2. The third chapter of this part continues thereafter with the overall technical principles asapplicable for the design of a self-elevating unit build under DNV GL classification.The technical requirements together with relevant calculations methods are discussed in detail in Ch.3 toCh.5. The three parts cover the main technical areas of class, subsequently materials and welding, hull andequipment and machinery and systems.Ch.6 to Ch.8 thereafter give a concise overview for specific phases of class involvement, that is respectivelyin the component and system certification process, the new building mechanical completion andcommissioning and conclusively survey and test requirements in the operational phase after delivery.For a clear separation between the content of this publication and other rules, standards or other servicedocuments, references to chapters and sections are related to this publication if not explicitly statedotherwise.

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5 Definitions

5.1 Verbal forms

Table 1 Verbal forms

Term Definition

shall verbal form used to indicate requirements strictly to be followed in order to conform to the document

shouldverbal form used to indicate that among several possibilities one is recommended as particularly suitable,without mentioning or excluding others, or that a certain course of action is preferred but not necessarilyrequired

may verbal form used to indicate a course of action permissible within the limits of the document

5.2 Definitions

Table 2 Definitions

Term Definition

approval or approved denotes acceptance by DNV GL of documentation showing design solutions, arrangementsand equipment that complies with the rules

assessment an act of assessing, appraising or evaluating a condition of a product, process or system

builder Signifies the party contracted to build a vessel in compliance with the Society's rules

certificate a document confirming compliance with the Society's rules or with other rules andregulations for which the Society has been authorized to act

certification a service confirming compliance with applicable requirements on the date that the surveywas completed

certification of materialsand components

the activity of ensuring that materials, components and systems used in vessels to beclassed by the society comply with the rule requirements

Guidance note:

The scope of classification re-quires that specified materials, components and systems intendedfor the vessel are certified. Depending on the categorisation, certification may include both planapproval and survey during production and/or of the final product.

The fabrication of major subcontracted parts of the newbuilding like legs, jackcase, pontoonsdeckboxes, columns, braces etc. are not considered as CMC but are part of the newbuilding andare covered by the applicable newbuilding rules. The subcontractor should comply with all rulesas applicable for newbuilding.

---e-n-d---o-f---g-u-i-d-a-n-c-e---n-o-t-e---

class class is assigned to and will be retained by vessels complying with applicable requirements ofthe Society's rules

classificationa service which comprises the development of independent technical standards for vessels –class rules and standards, and to verify compliance with the rules and standards throughoutthe vessels' life

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Term Definition

close-up examination an examination where the details of structural components are within the close visualinspection range of the surveyor, i.e. preferably within reach of hand

commissioning a process of assuring that components, equipment and the systems are functioning inaccordance with the functional requirements

concurrent surveys

surveys required to be concurrently completed shall have the same date of completionA survey required to be carried out in conjunction with or carried out as part of anothersurvey shall be completed on or before the completion of the other survey, however, withinthe time window for that survey.

condition of class constitutes a requirement that specific measures, repairs or surveys shall be carried outwithin a specific time limit in order to retain class

condition on behalf of theflag administration

constitutes specific measures, repairs or surveys that shall be carried out within a specifictime limit in order to retain the statutory certificateA CA will be issued only when the Society has been authorised to carry out statutory surveyson behalf of the flag ad-ministration.

contract

the specific agreement between DNV GL and the clientIt defines the extent of services requested by the customer, and is concerned with:

— the classification of vessels or installations, both new buildings and in operation— statutory work carried out on behalf of national maritime authorities— equipment and materials.

critical structural areasareas that have been identified from calculations to require monitoring or from the servicehistory of the subject vessel or from similar or sister vessels to be sensitive to cracking,buckling or corrosion which would impair the structural integrity of the vessel

customer signifies the party who has requested the Society's service

designer signifies a party who creates documentation submitted to the Society for approval orinformation

escape means for leaving the various workplaces on the unit or installation leading to a safe placeand without directly entering the sea

essential servicegenerally defined as a service which needs to be, in continuous operation for maintainingthe unit’s manoeuvrability (if applicable), or whose loss or failure would create an immediatedanger to the unit

exceptional circumstancesunavailability of dry-docking facilities; unavailability of repair facilities; unavailability ofessential materials, equipment or spare parts; or delays incurred by action taken to avoidsevere weather conditions

flag administration the maritime administration of a vessel's country of registry

guidance note contain advice which is not mandatory for the assignment or retention of class, but withwhich the Society, in light of general experience, advises compliance

important services

generally defined as a service which needs not necessarily be in continuous operation butwhose failure or non-availability would not create an immediate danger but impairs the unit’ssafety

Guidance note:

Systems and equipment providing the service above are essential respectively important. Thisapplies also to systems and equipment supporting these like control and electrical systems.


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Term Definition

independent tankself-supporting tank which does not form part of the vessel's hull and does not contribute tothe hull strengthIndependent gravity tank is a tank with design vapour pressure not exceeding 0.7 bar.

interpretations

norms for fulfilling the associated principle requirements as defined by other regulatorybodies on matters which are left to the satisfaction of the flag administration or are vaguelywordedThese do not preclude the use of other alternative solutions but these shall be documentedand approved for compliance to the principal requirement equivalent to the originalinterpretation.

load resistance factordesign structural analysis and design method

manufacturersignifies the entity that manufactures the material or product, or carries out part productionthat determines the quality of the material or product, or does the final assembly of theproduct

mechanical completionverification that the components, equipment and the systems are constructed, installed andtested in accordance with applicable drawings and specifications and are ready for testingand commissioning in a safe manner

memorandum to owner

constitutes information related to the ship, its machinery and equipment or to rulerequirementsAn MO will be issued in relation to information that does not require any corrective action orsurvey.

overall examination an examination intended to report on the overall condition of the structure

plan approval signifies a systematic and independent examination of drawings, design documents orrecords in order to verify compliance with the rules or statutory requirements

preload tank

a tank within the hull of a self-elevating unitThese tanks are periodically filled with salt water ballast and used to preload the footings ofthe unit prior to commencing drilling operations. Preload tanks are considered equivalent toballast tanks.

pressure vessel a tank with design gas or vapour pressure exceeding 0.5 bar

prompt and thoroughrepair

a permanent repair completed at the time of survey to the satisfaction of the surveyor,therein removing the need for the imposition of any associated condition of class

quality system signifies both the quality management system and established production and controlprocedures

quality survey plan

a plan that systematically identifies activities related to the classification project (e.g.,construction, installation, testing, mechanical completion, pre-commissioning, testing andcommissioning) and the extent of involvement each party (i.e., yard's QC, yard's QA, DNV GLand owners (if desired)) will undertake

Such a plan needs to be submitted to the Society for approval prior to commencement ofclassification projects.

reliability the ability of a component or a system to perform its required function under givenconditions for a given time interval

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Term Definition

representative tanks

those tanks which are expected to reflect the condition of other tanks of similar type andservice and with similar corrosion protection systemsWhen selecting representative tanks account shall be taken of the service and repair historyon board and identifiable critical and/or suspect areas.

reviewsignifies a systematic examination of drawings, design documents or records in orderto evaluate their ability to meet requirements, to identify any problems and to pro-posenecessary actions

safety systemssystems needed to be continuous available or available on demand to prevent, to detect, tocontrol or to mitigate the effects of an undesirable event, and to safeguard the personnel,environment and the installation

sighting surveya survey to confirm that the relevant construction or the equipment is in a satisfactorycondition and, as far as can be judged, will remain so until the postponed survey has beencarried out

significant repaira repair where machinery is completely dismantled and re-assembledSignificant repairs will, furthermore, be cases of repairs after serious damage to machinery.

The Society signifies DNV GL

safety systems systems, including required utilities, which are provided to prevent, detect/ warn of anaccidental event/abnormal conditions and/or mitigate its effects

spaces separate compartments including holds and tanks

statement of compliancea document confirming compliance with specified requirementsSuch documents may be issued by the Society in cases where it has not been authorised tocertify compliance.

statutory certificates IMO convention certificates issued on behalf of, or by, national authorities

statutory survey survey carried out by or on behalf of a flag administration

substantial corrosion extent of corrosion such that assessment of corrosion pattern indicates wastage in excess of75% of allowable margins, but within acceptable limits

survey

signifies a systematic and independent examination of a vessel, materials, components orsystems in order to verify compliance with the rules and/or statutory requirementsSurveys will be carried out on the vessel, at the construction or repair site as well as at sub-suppliers and other locations at the discretion of the Society, which also decides the extentand method of control.

suspect areas areas showing substantial corrosion and/or are considered by the surveyor to be prone torapid wastage

temporary conditions design conditions not covered by operating conditions, e.g. conditions during fabrication,mating and installation phases, dry transit phases

temporary equipmentequipment intended for use on installations and which is covered by class, requires hook-upto systems covered by class and/or is a significant deck load and/or may pose a risk for fire,explosion and escape routes

transit conditions all wet vessel movements from one geographical location to another

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Term Definition

transverse section

section which includes all longitudinal members such as plating, longitudinals and girdersat the deck, side, bottom, inner bottom and hopper side plating, longitudinal bulkhead andbottom plating in top wing tanks, as applicableFor transversely framed vessels, a transverse section includes adjacent frames and their endconnections in way of transverse sections.

verificationa service that signifies a confirmation through the provision of objective evidence (analysis,observation, measurement, test, records or other evidence) that specified requirements havebeen met

witnessing signifies attending tests or measurements where the surveyor verifies compliance withagreed test or measurement procedures

working stress design structural analysis method

5.3 AbbreviationsThe abbreviations in Table 3 are used.

Table 3 Abbreviations

Abbreviation In full

CA condition on behalf of the flag administration

CC condition of class

CMC certification of materials and components

ESD emergency shut down

FMEC failure mode effect and criticality analysis

FUI fatigue utilisation index

IACSThe International Association of Classification SocietiesUnified rules, interpretations, guidelines and recommendations may be found on www.iacs.org.uk.

IMO International Maritime Organization

HP high pressure

ISO International Organisation for Standardization

LRFD load resistance factor design

MC mechanical completion

MO memorandum to owner

OEM original equipment manufacturer

QSP quality survey plan

UT ultrasonic testing

WSD working stress design

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CHAPTER 2 GENERAL REGULATIONS AND CONDITIONS

SECTION 1 CLASSIFICATION PRINCIPLES

1 GeneralGeneral regulations and procedures are described in DNVGL-RU-OU-0101 Ch.1 Rules for classification ofoffshore drilling and support units.Specific requirements and relevant instructions for classing conventional self-elevating units are contained inthis rule chapter.Deviation from the requirements may be substituted where shown to provide equivalent or higher levelof integrity and safety. Any deviation from the requirements shall be documented and agreed between allcontracting parties.For a complete understanding of this chapter is referred to DNVGL-RU-OU-0101.

2 ApplicationThese rules are intended for self-elevating units of conventional design, that is:

— independent legs— not designed for field- or ocean transits under own power— diesel driven generators— rack and pinion type jacking system.

For other types of offshore units and self-elevating units with design alternatives or technical solutions notcovered in these rules, see DNVGL-RU-OU-0101.Unless stated otherwise, the coming into force date for these rules and the documents referenced by theserules as technical basis for classification shall be six (6) months after the date of publication.

2.1 Interpretations

2.1.1 These rules and the technical standard as being referred to are based on internationally acceptedprincipal requirements. In cases where these

a) contain only functional requirementsb) allow alternative solutions to prescriptive requirements orc) are generally or vaguely worded,

a DNV GL interpretation has been added.

2.1.2 The interpretations are not aiming at introducing additional requirements but at achieving uniformapplication of the principal requirements. The interpretations can be regarded as norms for fulfilling theprinciple requirements.

2.1.3 The interpretations do not preclude the use of other alternative solutions. Such solutions shallbe documented and approved for compliance to the principal requirement equivalent to the originalinterpretation.

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3 Class scope and notations

3.1 ScopeClassification follows the technical scope as described in Ch.2 Sec.3 [2] and covers the design, construction,commissioning and operational phases of the unit.

3.2 NotationsVessels build under compliance of the requirements and procedures of these rules shall be given the classnotation +1A Self-elevating Drilling Unit.Table 1 lists most relevant additional class notation for non-self-propelled, self-elevating units. A complete listof additional class notations can be found in DNVGL-RU-OU-0101 Ch.1 Sec.3 [2.6] and in DNV rules for shipsPt.1 Ch.2.

Table 1 Additional class notation for non-self-propelled, self-elevating units

Classnotation Description Qualifier Description Design requirements

Crane-offshore Covering onboard crane DNVGL-RU-OU-0101 Ch.2 Sec.7 [9]

DRILL Drilling plant DNVGL-OS-E101

E0 Periodically unattendedmachinery space DNV rules for ships Pt.6 Ch.3

ECO Machinery centralizedoperated DNV rules for ships Pt.6 Ch.3

ES Enhanced control andsafety systems Ch.5 Sec.6

<none> Structure

S Vessel safety

H Helicopter safetyHELDK Helicopter deck

F Helicopter facilities

DNVGL-OS-E401 Ch.2

ISDS Integrated softwaredependent systems (...) See DNVGL-OS-D203 for

qualifier definitions DNVGL-OS-D203

Recyclable Inventory of hazardousmaterials part 1 DNV rules for ships Pt.6 Ch.27

RENEWCovering mid-lifestructural and systemupgrades

Ch.8 Sec.6

1 Vessel mounted systemexcluding subsea equipment

WELL Well intervention system

2 Vessel mounted systemincluding subsea equipment

DNVGL-OS-E101

WELLTEST Well test system DNVGL-OS-E101 Ch.3

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SECTION 2 PROCEDURES

1 Plan approval

1.1 FormatThe documentation for plan approval may be submitted on paper or as an electronic file. Any documentssubmitted for re-approval or re-examination shall be especially marked to identify the revised parts. Symbolsused shall be explained, or reference to a standard code shall be given. Each drawing shall include a title fieldstating:

— name of vessel (when known)— name of document issuing company— name and signature of originator and verifier— document no.— document title— revision no.— issue date— scale— set of measurement units used in the document, e.g. System International— the document title should not include the name of the vessel. The document title should include the

function or component covered by the document.

Unique revision numbers shall be allocated to all issues of a document, including the first issue. Fordocuments with multiple sheets, the revision number should be the same for all sheets.

1.2 SubcontractorsWhere subcontractors and suppliers are involved, the customer shall co-ordinate the submission of requiredplans and documents, as well as co-ordinate any approval comments given by the Society. This does notapply for materials, components and systems requiring certification as is discussed in more detail in Ch.6.

1.3 Plans and data to be submittedGeneral list of plans and data to be submitted are included in the applicable technical chapters of Ch.3 toCh.5. A detailed and project specific list shall be supplied by DNV GL directly after the class agreement hasbeen signed. Project specific implies that only those documentation is required as is relevant for the designand within the scope of the contractual agreement between yard and DNV GL.

2 CertificationThe scope of classification requires that specified materials, components and systems intended for the vesselare certified according to the rules. The objective of certification shall ensure that materials, components andsystems used in vessels to be classed by the Society comply with the rule requirements.Certification normally includes both plan approval and survey during production and/or of the final product.A detailed description of the certification process and the specific requirements and lists of the specifiedmaterials, components and systems is given in Ch.6.

Guidance note:

The mentioned systems may be installed in (top-side) modules, or other subcontracted parts like legs, pontoons etc.Notwithstanding, the modules/ parts are not part of the material, component and system certification as described in Ch.6, but areconsidered as part of the newbuilding process.


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3 Testing and surveysDuring the building period DNV GL carries out surveys at the building yard and its suppliers. The purpose ofthese is to verify that the construction, components and equipment satisfy the rule requirements and are inaccordance with the approved plans, that required materials are used, and that functional tests are carriedout as prescribed by the rules. A complete description of these test and surveys is given in Ch.7.

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SECTION 3 PRINCIPLES AND CONDITIONS

1 GeneralThe table below lists references required for a complete understanding of this chapter.

Table 1 Overview of applicable standards

Reference Title

DNVGL-OS-A101 Safety principles and arrangements

DNVGL-OS-D101 Marine and machinery systems and equipment

DNVGL-OS-D201 Electrical installations

DNVGL-OS-D202 Automation, safety, and telecommunication systems

DNVGL-OS-D301 Fire protection

2 Design principles

2.1 ScopeThese rules with the referred standards give requirements in the following areas:

1) Hull and main structure

— strength— materials and welding— corrosion protection— passive fire protection— weathertight and watertight integrity— stability and floatability.

2) Marine and machinery installations and equipmentMachinery installations and equipment, including their related auxiliary systems, to the following mainfunctions:

— jacking gear— fire extinguishing— drainage and bilge pumping— ballasting— emergency shutdown systems.

3) Systems and equipment provided to prevent, detect/ warn of an accidental event and/or prevent ormitigate its effects.

4) Secure integrity of shelter areas and usability of escape ways and means of evacuation.

2.2 Safety and important systemsTo further frame the content of the rules, the above listed areas and systems are split into safety, essentialand important systems.Safety systems are systems needed to be continuous available or available on demand to prevent, to detect,to control or to mitigate the effects of an undesirable event, and to safeguard the personnel, environmentand the installation. Examples of safety systems covered by main class:

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— fire pumps— emergency shut down (ESD) system— fire and gas detection and alarm system— systems required to be supplied from batteries or emergency generator, e.g. public address, emergency

lighting— electric generators and associated power sources supplying the above equipment— control, monitoring and safety devices or systems for safety systems.

Essential and important services ensure reliable operation and maintain the units operation within operationallimitations. Examples of equipment or systems for important services covered by main class:

— fuel oil transfer pumps and fuel oil treatment equipment— seawater pumps (note)— starting air and control air compressors— bilge- and ballast/preload pumps— ventilating fans for engine rooms— ventilating fans for gas dangerous spaces— main lighting system— watertight closing appliances— jacking system— bilge alarm system— electric generators and associated power sources supplying the above equipment— control, monitoring and safety devices or systems for the above equipment— seawater pumps (if used as part of a fire water supply system).

2.3 RedundancySafety systems are always to be available. To secure that safety systems always are available, the generalprinciple is that components and systems shall be arranged with redundancy so that a single failure ofany active component or system does not cause loss of any main function. Availability is as such furtherindirect defined in the requirement to a system (where this general principle may be waived and/ or whereduplication of components is required).Redundancy can either be arranged by installing more than one unit (component redundancy) or by havingtwo or more systems capable of performing the same functions (system redundancy).For redundancy on a component level a single failure of an active component shall not lead to a reduction ofthe output power for the main function served.When two or more components are performing the same function, these shall be mutually independentand at least one shall be independently driven. Components arranged as part of the designed redundancy,yet only performing important functions to a main unit, can be directly powered by the main unit throughseparate power transmissions, on the condition that these components are not necessary for the starting ofthe main unit.When traditional mechanical components are replaced by electronic components, these components shallhave the same reliability as the mechanical component being replaced.Machinery or equipment having remote or automatic control, shall have additional alternative provisions forattendance and operation.

2.4 Failure effectsIn the event of failure, components and systems shall enter the least hazardous of the possible failure stateswith regard to machinery, personnel and environment.Failure of one component in a system arranged as part of the designed redundancy shall not lead to failure ordamage to backup or parallel components or systems.For failure detection see Ch.5 Sec.4 [2.2].

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3 Environmental conditions

3.1 PrinciplesSelf-elevating units shall be based on environmental conditions specified by the designer. Worldwide serviceoperation is not applicable.unless otherwise specified in the detailed requirements for the component or system, all components andsystems covered by this standard shall be designed to operate under the following environmental conditions

3.2 Design temperatureThe unit’s design temperature is a minimum temperature used as a criterion for the selection of steel grades.The design temperature shall be specified by the customer and shall be taken as the lower or equal to thelowest mean daily temperature in air for the relevant areas. For seasonal restricted operations the lowestmean daily temperature in air for the season may be applied.

Guidance note:

It is underlined that design temperatures below 0°C are only relevant for waters in the higher latitudes (e.g. northern part of NorthSea, Canadian waters etc). For these waters and their harsh conditions, relevant considerations should be taken (e.g. DNVGL-OS-C201 Ch.2 Sec.1 [2.3.4] on water trapped in local structures, DNVGL-OS-D101 Ch.2 Sec.3 [6.1.8] on freezing of vents, DNVGL-OS-D301 in protecting the fire equipment against freezing etc) In addition, class notations related to cold climate operations aslisted DNVGL-RU-OU-0101 Ch.2 Sec.7 [19] can be relevant as well.


The design temperature shall be listed in the appendix to class certificate (see also Ch.7 Sec.5 [3]).Guidance note:

In some offshore standards is, in addition to a design temperature, a service temperature defined. For self-elevating units, the twotemperatures are equal.


3.3 Temperature for machinery systems and equipmentMachinery systems and equipment shall be constructed for continuous operation in the range of ambienttemperatures as specified in Table 2.

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Table 2

Minimum ambient air temperaturerange for continuous operation [°C]Location

From To

1 Engine rooms, boiler rooms, galleys and similar spaces,accommodation spaces. 0 +451

2 Open deck, deckhouses and similar spaces which arenot provided with space heating. -25 +45

1 Where equipment is installed within environmentally controlled spaces the ambient temperature for which theequipment shall be suitable may be reduced from 45°C and maintained at a value not less than 35°C provided:

— the equipment is not for use for emergency services, and shall not be in operation after ESD has been activated— temperature control is achieved by at least two cooling units so arranged that in the event of loss of one cooling unit,

for any reason, the remaining unit(s) is capable of satisfactorily maintaining the design temperature— the equipment can be started in a 45°C ambient temperature and kept in operation until the lesser ambient

temperature may be achieved— the cooling equipment shall be rated for a 45°C ambient temperature— malfunction of, or loss of a cooling unit shall be alarmed at a manned control station.

In accepting a lesser ambient temperature than 45°C, it shall be ensured that electrical cables for their entire length areadequately rated for the maximum ambient temperature to which they are exposed along their length.

(see IACS UR E19)

For the different environmental classes and the specified temperature ranges as applicable for control- andcommunication equipment see DNVGL-OS-D202 Ch.2 Sec.4 [2].

3.4 Cooling water temperaturesElectrical equipment shall be constructed for continuous operation under full rated load, at a seawatertemperature range from 0 to +32°C.

3.5 HumidityAll equipment shall be constructed to withstand, and function safely in relative humidity up to 95%.

3.6 PerformanceFor performance requirements of machine systems, the conditions of Table 3 can be applied (see IACS URM28):

Table 3

Parameter Value

Total barometric pressure 1 bar

Ambient air temperature 45°C

Relative humidity of air 60%

Sea water temperature 32°C

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3.7 InclinationsAll machinery, components and systems essential for safe operation shall be designed for operation under thefollowing inclination values:

— inclination 10° from normal level in any direction under normal static conditions— inclination 15° from normal level in any direction under normal dynamic conditions.

Guidance note:

Other values may be accepted if justified by calculations for the particular offshore unit.

National authorities may require larger inclinations.


3.8 VibrationsElectrical equipment and components shall be constructed to withstand, without malfunctioning, or electricalconnections loosening, at least a vibration frequency range 5 to 50 Hz with vibration velocity amplitude 20mm/s.For flexible mounted equipment, special considerations shall be given to the construction of the equipmentsince larger vibrations may occur.For control- and communication equipment vibration requirements see DNVGL-OS-D202 Ch.2 Sec.4 [2].

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CHAPTER 3 MATERIALS AND WELDING

SECTION 1 METALLIC MATERIALS

1 GeneralTable 1 lists references required for a complete understanding of this chapter.


Reference Title

DNVGL-OS-C101 Design of offshore steel structures, general - LRFD method

DNVGL-OS-C201 Structural design of offshore units - WSD method

DNVGL-OS-C301 Stability and watertight integrity


DNVGL-OS-E301 Position mooring

2 PrinciplesPrinciples for certification of steels for structural application are given by standard DNVGL-OS-B101.Requirements for the specific materials selections are given in the technical chapters of Ch.4 and Ch.5 of thisbook:

Table 2 Overview of further details on certification of steel

Topic In this rule book Offshore standard

Structural steel Ch.4 Sec.1 [6.2]

DNVGL-OS-C101 Ch.2 Sec.3 [4] orDNVGL-OS-C201 Ch.2 Sec.3 [4]

DNVGL-OS-C104 Ch.2 Sec.1 [3] or

DNVGL-OS-C201 Ch.2 Sec.11 [2.3]1)

Watertight integrity, freeboard and weathertightclosing appliances DNVGL-OS-C301 Ch.2 Sec.2 [2]

Towline fastening devices and their supportingstructures Ch.4 Sec.3 [2.2] DNVGL-OS-C101 Ch.2 Sec.3

Anchors DNVGL-OS-E301 Ch.2 Sec.4

Windlasses, winches and chain stoppers DNVGL-OS-E301 Ch.2 Sec.2 [11.4]

Materials for piping Ch.5 Sec.1 [4.1] DNVGL-OS-D101 Ch.2 Sec.2 [2]

Jacking gear Ch.5 Sec.1 [6.3]

1) For the use of DNVGL-OS-C104 or the DNVGL-OS-C201 see Sec.1

When material other than steel and aluminium alloys (evidenced by previous service experience) is used instructural fabrication and for equipment relating to main class, documentation of the material’s applicability

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for intended purpose shall be documented with due regard to the material’s mechanical properties and itsresponding service performances.Materials with low heat resistance shall not be used in components where fire may cause outflow offlammable or toxic fluids, flooding of any watertight compartment or destruction of watertight integrity.

Guidance note:

Materials with high heat resistance are materials having a melting point greater than 925°C. Materials with low heat resistance areall other materials. Deviations from the above requirement will be subject to special considerations.


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SECTION 2 STRUCTURAL FABRICATION

1 GeneralPrinciples and requirements for structural fabrication are given by standard DNVGL-OS-C401 as discussed indetail in Sec.3.

2 Plans and data to be submittedPlans necessary to assess the joints and welding shall be submitted and approved before steel cutting. Ageneral overview of the content of the plans and analyses is listed in Table 1. A more detailed overview,tuned to the specific design and project scope can be obtained from DNV GL’s Nauticus Production System.Documentation shall be submitted as required by Table 1.

Table 1 Documentation requirements

Object Documentation type Additional description Info

H140 – Standard details FI

M060 – Non-destructive testing (NDT) plan APStructural fabrication

M061 – Holes and cutouts plan FI

H140 – Welding tables AP

M060 – Welding procedures APWelding

M061 – Welding procedure qualification record AP

For general requirements to documentation, including definition of the Info codes, see DNVGL-RU-SHIP Pt.1Ch.3 Sec.1.For a full definition of the documentation types, see DNVGL-RU-SHIP Pt.1 Ch.3 Sec.1.

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CHAPTER 4 HULL AND EQUIPMENT

SECTION 1 STRUCTURAL DESIGN

1 General

1.1 IntroductionTable 1 lists references required for a complete understanding of this chapter.


Reference Title

DNVGL-OS-A101 Safety principles and arrangement

DNVGL-OS-C104 Structural design of self-elevating units - LRFD method


DNVGL-OS-C401 Fabrication and testing of offshore structures


DNVGL-RP-C104 (recommendations for the strength analyses of main structures of) Self-elevating units

DNV-RP-C204 Design Against Accidental Loads

DNV-RP-C205 Environmental Conditions and Environmental Loads

1.2 ScopeThe classification scope includes the following structural elements:

— barge hull— jacking houses— legs with spudcan— superstructure— crane pedestals (below slewing ring)— support for lifting equipment— cantilever including drill floor (up and including support stools for derrick)— attachment of helideck support structure— foundation and support for heavy equipment (i.e. equipment where the static forces exceed 50 kN or

resulting static bending moments at deck exceed 100 kNm).

The scope may be extended by the selection of additional voluntary notations.Excluded from the scope are:

— ice and soil conditions— earthquake and other environmental events defined by an annual probability equal or lower than to 10-4.

Transit conditions are included in the structural design scope of work. Temporary conditions are not includedunless specifically specified.

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1.3 Plans and data to be submittedPlans necessary to assess the strength of the structure including the details of the joints and welding shallbe submitted and approved before steel cutting. A general overview of the content of the plans and analysesis listed in Table 2. A more detailed overview, tuned to the specific design and project scope can be obtainedfrom DNV GL’s Nauticus Production System.



C030 – Detailed drawing Fastening of anodes in ballast tanks AP

C030 – Detailed drawingFastening of anodes in liquid cargo tanks,for cargo with flash point below 60°C, andadjacent tanks

AP

M050 – Cathodic protectionspecification, calculation anddrawings

FI

Sacrificial anodes

Z030 – Arrangement plan In ballast tanks, in/on spudcans AP

Vessel arrangement Z010 – General arrangementplan FI

H010 – Structural design brief FI

H020 – Design load plan Including cantilever load chart FI

H030 – Tank and capacity plan FI

H040 – Structuralcategorisation plan AP

H041 – Structural inspectionplan AP

H050 – Structural drawing AP

H081 – Global strengthanalysis

Elevated survival, preloading and operatingconditions FI

H081 – Global strengthanalysis

Temporary conditions, e.g. leg bottom impact,jacking FI

H081 – Global strengthanalysis Operation in partly submerged condition FI

H081 – Global strengthanalysis Transit conditions FI

H090 – Model testdocumentation

Required for novel designs, or unprovenapplications of designs where limited or nodirect experience exists

FI; R

H120 – Docking arrangementplan FI

Self elevating unit structure

H132 – Tank testing plan AP

Leg foundations H050 – Structural drawing AP

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H080 – Strength analyses Including connections to the legs FI

H085 – fatigue analysis FI

H050 – Structural drawing AP

H080 – Strength analyses Including transit and elevated conditions FILegs

H085 – Fatigue analysis Including transit and elevated conditions FI

Leg > Lattice leg chord racks C060 – Mechanical componentdocumentation AP

H050 – Structural drawing Including decks, bottom, external- andinternal bulkheads AP

Hull

H080 – Strength analyses

Including variable functional loads andequipment (variable and fixed) loads on deckstructures, and combinations of global andlocal stresses

FI

H050 – Structural drawing FI

H080 – Design analyses APCantilevers

H085 – fatigue analysis Connections to hull FI

H050 – Structural drawing FIDeck Houses

H080 – Design analyses FI

Accommodation modulestructure H080 – Design analyses AP

Accommodation module H050 – Structural drawing AP

Accommodation modulesubstructure H050 – Structural drawing AP

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H050 – Structural drawing APJackhouses (incl. fixationsystem support and jackingsystem support)Supporting structures for:

— helicopter deck— accommodation module— derrick— drill floor— lubrication oil— independent tanks

drilling fluid return tripindependent tanks

— main generator— auxiliary boiler— auxiliary feed water— independent tanks— helicopter fuel storage

tanks— ballast pumping unit— internal watertight door/

ramp— anchor winch1 anchor

chain stopper1

— anchor fairlead structure1

— passive towingequipment2

— offshore crane1

— sea chests— offshore crane pedestal

H080 – Strength analysesIncluding footprint.

FI

Jackhouses H085 – fatigue analysis Including hull structures adjacent to legs andjackhouses FI

1) Applicable if static force > 50 kN or bending moment > 100 kNm.2) Including towing force design loads and winch load footprint

For general requirements to documentation, including definition of the Info codes, see DNVGL-RU-SHIP Pt.1Ch.3.

2 PrinciplesThe unit or installation shall be designed and constructed with sufficient integrity to withstand operationaland environmental loading throughout its life-cycle.Systems and structures shall be designed with suitable functionality and survivability for prevention of, orprotection from, design accident events affecting the unit or installation. Refer also DNV-RP-C204 DesignAgainst Accidental Loads.The structure shall be designed to resist relevant loads associated with conditions that may occur during allstages of the life-cycle of the unit. The conditions that should be considered are:

— transit condition(s)— installation condition

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— operating condition(s)— survival condition— retrieval condition.

Both the Load resistance factor design (LRFD) and the Working stress design (WSD) methods are acceptablefor structural design and analysis.DNVGL-OS-C104 should be used as reference standard if the LRFD method is adopted, supplemented bygeneral requirements from DNVGL-OS-C101 (where referenced). DNVGL-OS-C201 should be used for WSDmethod. In the remaining of this chapter, reference to both standards are given for completeness.

3 Analysis and calculations

3.1 GeneralStructural analysis shall be performed to evaluate the structural strength due to global and local effectsas described in DNVGL-OS-C104 Ch.2 Sec.2 [4] or DNVGL-OS-C201 Ch.2 Sec.11 [5] as listed in the tablebelow.

Table 3

Description Reference in DNVGL-OS-C104 Reference in DNVGL-OS-C201

General DNVGL-OS-C104 Ch.2 Sec.2 [4.1] DNVGL-OS-C201 Ch.2 Sec.11 [5.1]

Global structural models DNVGL-OS-C104 Ch.2 Sec.2 [4.2] DNVGL-OS-C201 Ch.2 Sec.11 [5.2]

Local structural models DNVGL-OS-C104 Ch.2 Sec.2 [4.3] DNVGL-OS-C201 Ch.2 Sec.11 [5.3]

Fatigue See [3.2] below

Recommended methods for analysis and calculations are described by DNVGL-RP-C104.

3.2 Fatigue analysisA fatigue strength analysis according to DNVGL-OS-C104 Ch.2 Sec.5 or DNVGL-OS-C201 Ch.2 Sec.6 andDNVGL-OS-C201 Ch.2 Sec.11 [8] shall be undertaken for members and joints for which fatigue fracture ispossible mode of failure. For conventional jack-ups the following areas shall normally be assessed:

— spudcans and leg at the leg-to spudcan connection— leg and hull/jacking structure at and around the leg-to-hull connections— joints and members of legs (e.g. span breakers) located at and around the splash zone.

The required models and methods for fatigue analysis for self-elevating units are dependent on type ofoperation, environment and design type of the unit. For units operating at deeper waters where the firstnatural periods of the unit are within the range of significant wave energy, the associated dynamic structuralresponses shall be considered in the fatigue analysis. For natural periods higher than 3 sec, the dynamicstructural response shall also be considered in the fatigue analysis.The design life for the structure components shall be minimum 20 years.

4 Design and loading conditions

4.1 GeneralEach structural member shall be designed for the least favourable of the loading conditions given in the tablebelow.

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Table 4 Loading conditions

Case Description

a) functional loads

b) maximum combination of environmental loads and associated functional loads

c) accidental loads and associated functional loads

d) annual most probable value of environmental loads and associated functional loads after credible failures, orafter accidental events

e) annual most probable value of environmental loads and associated functional loads in a heeled conditioncorresponding to accidental flooding

Relevant loading conditions for the different design condition are shown in Table 5.

Table 5

Loading conditionsDesignconditions a) b) c) d) e)

Reference

Transit x x x DNVGL-OS-C104 Ch.2 Sec.2 or DNVGL-OS-C201 Ch.2 Sec.11

Installation x DNVGL-OS-C104 Ch.2 Sec.2 or DNVGL-OS-C201 Ch.2 Sec.11

Operation x x x x DNVGL-OS-C104 Ch.2 Sec.2 or DNVGL-OS-C201 Ch.2 Sec.11

Survival x x DNVGL-OS-C104 Ch.2 Sec.2 or DNVGL-OS-C201 Ch.2 Sec.11

Retrieval x DNVGL-OS-C104 Ch.2 Sec.2 or DNVGL-OS-C201 Ch.2 Sec.11

Load cases shall be established for the various design conditions based on the least favourable combinationsof functional loads, environmental loads and/or accidental loads.Limiting environmental and operating conditions (design data) for the different design conditions shall bespecified by owner or designer.Limiting design criteria for going from one design condition to another shall be specified by owner or designerand be clearly established and documented.If the unit is intended to be dry docked, the footing structure (i.e. spudcans) and/or the barge shall besuitably strengthened to withstand the loads.

4.2 Environmental conditionsEnvironmental conditions for design of self-elevating units are given by DNVGL-OS-C104 Ch.2 Sec.3 [4] orDNVGL-OS-C201 Ch.2 Sec.11 [4].Combination of loads are given in DNVGL-OS-C104 Ch.2 Sec.3 or DNVGL-OS-C201 Ch.2 Sec.2 [6] andDNVGL-OS-C201 Ch.2 Sec.11 [6.12].In conjunction with combination of environmental loads for loading condition b) (see DNVGL-OS-C104Ch.2 Sec.3, DNVGL-OS-C104 Ch.2 Sec.4 [4.2.1] or DNVGL-OS-C201 Ch.2 Sec.2 [6.1.4]) the sustainedwind velocity, i.e. the 1 minute average velocity, shall be used. If gust wind alone is more unfavourablethan sustained wind in conjunction with wave forces, the gust wind velocity shall be used. For local loadcalculations gust wind velocity shall be used.Principles and formulas for calculation of wind loads may be taken from DNV-RP-C205 Sec.2.

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Guidance note:

Service restrictions due to wind action is to be specified by the customer/designer. Unrestricted world wide operation is notapplicable for self-elevating units, however, a wind velocity of not less than 51.5 m/s (1min at 10m) combined with maximumwave forces will cover most locations. The corresponding wind force should be based on a wind velocity profile given in DNVGL-RP-C104 [2.4].


5 Loads and load effects

5.1 GeneralLoads and load effects are given by DNVGL-OS-C104 and DNVGL-OS-C201 as listed in the table below.

Table 6 Overview on applicable loads

Description Reference in DNVGL-OS-C104 Reference in DNVGL-OS-C201

Permanent functional loads DNVGL-OS-C104 Ch.2 Sec.3 [2] DNVGL-OS-C201 Ch.2 Sec.2 [3] andDNVGL-OS-C201 Ch.2 Sec.11 [6.2]

Variable function loads DNVGL-OS-C104 Ch.2 Sec.3 [3] DNVGL-OS-C201 Ch.2 Sec.2 [4] andDNVGL-OS-C201 Ch.2 Sec.11 [6]

Tank loads DNVGL-OS-C104 Ch.2 Sec.3 [3.3] DNVGL-OS-C201 Ch.2 Sec.2 [4.3] andDNVGL-OS-C201 Ch.2 Sec.11 [6.5]

Environmental loads DNVGL-OS-C104 Ch.2 Sec.3 [4] DNVGL-OS-C201 Ch.2 Sec.2 [5] andDNVGL-OS-C201 Ch.2 Sec.11 [6.5] toDNVGL-OS-C201 Ch.2 Sec.11 [6.11]

Accidental loads DNVGL-OS-C104 Ch.2 Sec.3 [6] DNVGL-OS-C201 Ch.2 Sec.2 [7]

Deformation loads DNVGL-OS-C104 Ch.2 Sec.3 [5] DNVGL-OS-C201 Ch.2 Sec.2 [8]

Fatigue loads DNVGL-OS-C104 Ch.2 Sec.3 [7] DNVGL-OS-C201 Ch.2 Sec.6 andDNVGL-OS-C201 Ch.2 Sec.11 [8]

5.2 Accidental loadsAccidental loads are loads related to abnormal operations or technical failure. Relevant accidental events aregiven in DNVGL-OS-C104 Sec.6.

Table 7 Overview on relevant accidental loads

Description Reference in DNVGL-OS-A101, DNVGL-OS-C104, DNVGL-OS-C201 and DNVGL-OS-C301

Dropped objects DNVGL-OS-A101 Sec.2 [4.2] and DNVGL-OS-C201 Ch.2Sec.7 [2.3]

Collision loads DNVGL-OS-A101 Sec.2 [4.3] and DNVGL-OS-C201 Ch.2Sec.7 [2.2]

Unintended flooding DNVGL-OS-C301 Ch.2 Sec.1 [5.1] and DNVGL-OS-C301Ch.2 Sec.1 [5.3]

Explosions loads DNVGL-OS-A101 Sec.2 [4.6] and DNVGL-OS-C201 Ch.2Sec.7 [2.5]

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6 Structural categorization, material and inspection principles

6.1 Structural categorizationApplication categories for structural components are defined in DNVGL-OS-C104 Ch.2 Sec.1 and DNVGL-OS-C201 Ch.2 Sec.3. Structural members of self-elevating units with separate footing are normally found in thefollowing groups:

a) Special category

— Highly stressed elements of bottom of leg, including leg connection to spudcan.— Intersections of lattice type- or trussed leg structure, which incorporates novel construction, including

the use of steel castings.— Areas of concentrated stresses in elements of guide structures, jacking and locking system(s),

jackhouse and support structure.— Areas of concentrated stresses in elements of supporting structures to other heavy substructures like

cantilever, crane pedestal etc.

b) Primary category

— Combination of bulkhead, deck, side and bottom plating within the hull which forms “Box” or “I” typeacting as main beam

— All components of lattice type legs and external plating of cylindrical legs.— Jackhouse supporting structure and bottom footing structure, which receives initial transfer of load

from legs.— Internal bulkheads, shell and deck of spudcan which are designed to distribute major loads, either

uniform or concentrate.— Main support structure of heavy substructures and equipment, e.g. cranes, drill floor substructure, life

boat platform and helicopter deck.Guidance note:

Fatigue critical details within structural category primary are inspected according to requirements in category I as stated inDNVGL-OS-C101 Ch.2 Sec.3 [3.3].


c) Secondary category

— Deck, side and bottom plating of hull except areas where the structure is considered primary orspecial application.

— Bulkheads, stiffeners, decks and girders in hull that are not considered as primary or specialapplication.

— Internal bulkheads and girders in non-trussed legs.— Internal bulkheads, stiffeners and girders of spudcan structures, except where the structures are

considered primary or special application.Guidance note:

Fatigue critical details within structural category secondary are inspected according to requirements in category I as stated inDNVGL-OS-C101 Ch.2 Sec.3 [3.3].


6.2 Material selectionGeneral requirement to material selection are given by DNVGL-OS-C104 Ch.2 Sec.1 [3] and DNVGL-OS-C201Ch.2 Sec.3 [4].For steel plates intended for racks and split tubes in rack and pinion jacking systems with servicetemperature down to -20°C, and where minimum yield stress equal to 690 N/mm2 is specified, grade VLE690 may replace VL F690 for thicknesses in the range 80 to 250 mm, provided the materials are Charpy

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V-notch impact tested at ½ t (mid thickness) at – 40°C in the transverse direction and satisfying an energyrequirement of 46J.The above also apply to steel plates/racks intended for legs of circular or polygonal shape, steel plates/racksin triangular chord sections, and steel plates in primary areas for jack-cases.

7 Structural strength

7.1 GeneralGeneral requirements for LRFD design are given by DNVGL-OS-C101 Ch.2 Sec.4 to Sec.7 for each limit state,with specific considerations for Self-Elevating units in DNVGL-OS-C104 Ch.2 Sec.4 to DNVGL-OS-C104 Ch.2Sec.6.General requirements for WSD design are given by DNVGL-OS-C201 Ch.2 Sec.4 with specific considerationsfor self-elevating units in Sec.11 [7]. Detailed references are as listed in Table 8.

Table 8 Overview on topics related to structural strength

Description Reference in DNVGL-OS-C101 andDNVGL-OS-C104

Reference in DNVGL-OS-C201 Ch.2

Flat plated structures and stiffenedpanels

DNVGL-OS-C101 Ch.2 Sec.4 [2] Sec.4 [2]

Shell structures DNVGL-OS-C101 Ch.2 Sec.4 [3] Sec.4 [3]

Tubular members, tubular joints andconical transitions


Non-tubular beams, columns andframes


Strength of plating and stiffeners DNVGL-OS-C101 Ch.2 Sec.4 [6] Sec.5 [2]

Bending and shear in girders DNVGL-OS-C101 Ch.2 Sec.4 [7] Sec.5 [3]

Global capacity DNVGL-OS-C104 Ch.2 Sec.4 [2.1] Sec.11 [7.2]

Footing strength DNVGL-OS-C104 Ch.2 Sec.4 [2.2] Sec.11 [7.3]

Leg strength DNVGL-OS-C104 Ch.2 Sec.4 [2.3] Sec.11 [7.4]

Jackhouse support strength DNVGL-OS-C104 Ch.2 Sec.4 [2.4] Sec.11 [7.5]

Hull strength DNVGL-OS-C104 Ch.2 Sec.4 [2.5] Sec.11 [7.6]

7.2 Footing strengthSpud cans shall be designed by taking into account the effect of uneven distribution from seabed conditionsand scouring.The strength checks for the spudcan, the leg-to-spudcan connections and the two lowest leg bays (latticelegs) for separate type spudcans should normally not be based on lower loads than given below:

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i) The design load Fv is evenly distributed over 50% of the bottom area: and,q = design contact pressureMe = design eccentricity momentFv = maximum design axial load in the leg accounting for functional loads and environmental

overturning loadsR = equivalent radius of spudcan contact area.

ii) The design load Fv is concentrically distributed over a range of bearing areas, from the minimum designpenetration (supported on spudcan tip) up to and including full spudcan bottom area.

iii) If elevated condition is designed based on pinned leg footings; the spudcan and the leg-to-spudcanconnections shall be designed for the maximum vertical reaction and the associated horizontal reactionin conjunction with 35% of the maximum calculated moment at the lower guide (to account for theeccentric effects of possible scour and uneven bottom conditions) acting in the most unfavourabledirection. The maximum lower guide bending moment shall be calculated with pin-ended conditions.

iv) If elevated condition is designed based on moment fixity at leg footings:

— The maximum vertical reaction, in conjunction with the associated horizontal reaction and spudcan-soil fixity moment, acting in the most unfavourable direction.

— The maximum spudcan-soil fixity moment in conjunction with the associated vertical and horizontalreactions, acting in the most unfavourable direction.

— The design moments and soil pressures above are based on a relative homogenous seabed, forexample for sand or clay seabed. Local stiff soil supporting in the bottom plate outside the strong tipshould be avoided. It is assumed that this will be evaluated in the sea bed surveys in connection withsite specific assessments when the unit is used on specific locations.

Guidance note:

Cases (i) and (ii) above should always be checked together with one of the cases (iii) or (iv).

Case (iii) or (iv) is checked based on the leg footing assumption used in design.

For classification the design values in (i) to (iv) will be included in the appendix to classification certificate as basis for design of thespudcan and lower leg.


For other types of bottom support, e.g. mats special considerations should be made.

7.3 Section scantlingsThe requirements in this section are applicable for:

— plate thicknesses and local strength of panels— simple girders— calculations of complex girder systems.

Requirements are given in DNVGL-OS-C101 Ch.2 Sec.4 [6] or DNVGL-OS-C201 Ch.2 Sec.5 [2] for strengthof plating and stiffeners, and DNVGL-OS-C101 Ch.2 Sec.4 [7] or DNVGL-OS-C201 Ch.2 Sec.5 [3] for bendingand shear in girders.

7.4 Fatigue strengthDesign fatigue factor (DFF) shall be applied according to in DNVGL-OS-C201 Ch.2 Sec.11 [8] or DNVGL-OS-C104 Ch.2 Sec.5 [1]. Units intended to operate continuously at the same location for more than 5 years shallcomply with the requirements given in DNVGL-OS-C104 App.A or DNVGL-OS-C201 App.C.Relevant fatigue analysis are given in Ch.4 Sec.1 [3.2].

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8 Weld connectionsRequirements for weld connections is given by DNVGL-OS-C101 Ch.2 Sec.8 or DNVGL-OS-C201 Ch.2 Sec.8as listed in Table 9.

Table 9 Overview on requirements for weld connections

Description Reference in DNVGL-OS-C101 or DNVGL-OS-C201

Butt joints Ch.2 Sec.8 [2.1]

Tee or cross joints Ch.2 Sec.8 [2.2]

Slot welds Ch.2 Sec.8 [2.3]

Lap joint Ch.2 Sec.8 [2.4]

Weld size Ch.2 Sec.8 [3]

9 Corrosion controlCorrosion control of structural steel for offshore structures comprises:

— coatings and/or cathodic protection— use of a corrosion allowance— inspection/monitoring of corrosion— control of humidity for internal zones (compartments).

Requirements for corrosion control are given by DNVGL-OS-C101 Ch.2 Sec.9 or DNVGL-OS-C201 Ch.2 Sec.9as listed in Table 10. The manufacturing/installation of systems for corrosion control are covered in DNVGL-OS-C401 Sec.5.

Table 10 Overview on requirements for corrosion control

Description Reference in DNVGL-OS-C101 or DNVGL-OS-C201

Techniques for corrosion control related to environmentalzones

Ch.2 Sec.9 [2]

Cathodic protection Ch.2 Sec.9 [3]

Coating systems Ch.2 Sec.9 [4]

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SECTION 2 STABILITY AND WATERTIGHT INTEGRITY

1 General

1.1 IntroductionThis section provides principles, technical requirements and guidance related to stability, watertight integrity,freeboard and weathertight closing appliances.Table 1 lists references required for a completed understanding of this chapter.


Reference Title

IMO MODU Code Code for the construction and equipment of Mobile Offshore Drilling Units, 2009

ICLL 1966 International Convention on Load Lines, 1966, amended by Protocol 1988

DNVGL-OS-B101 Metallic materials


DNVGL-RU-SHIP Pt.6 Ch.4 Sec.7 Loading computer systems for stability and longitudinal strength - LCS


1.2 Plans and data to be submittedA general overview of the content of the plans and analyses is listed in Table 2. A more detailed overview,tuned to the specific design and project scope can be obtained from DNV GL’s Nauticus Production System.



B010 – Lines plan and offset tables FI

B020 – External watertight integrityplan FI

B040 – Stability analysis AP

B050 – Preliminary stability manual AP

B100 – Inclining test and lightweightsurvey procedure AP

Stability

B110 – Final stability manual AP

B030 – Internal watertight integrity plan FI

Damage stability B070 – Preliminary damage stabilitycalculation AP

External watertightand weathertightintegrity

B200 – Freeboard plan AP

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Internal watertightdoor / ramp Z030 – Arrangement plan

Applicable for all watertight doors. Includingfor each door: Size, design principle (sliding,hinged), pressure rating and fire rating.Including remote control positions.

AP

Internal watertightdoors / rampshydraulic powersystem

S010 – Piping diagram AP

Internal watertightdoors > doorstructure

C030 – Detailed drawing AP

Service hatchways C010 – Design criteria FI

Ventilation System S012 – Ducting diagram AP

For general requirements to documentation, including definition of the codes and documentation types, seeDNVGL-RU-SHIP Pt.1 Ch.3.

2 StabilityThis section gives requirements related to the following design parameters:

1) Buoyancy and floatability.2) Wind exposed portions.3) Draught range at various modes of service.4) Lightweight and loading conditions.

The combination of the design parameters (1 to 4) will determine the maximum allowable vertical centre ofgravity (VCG) of the unit at the applicable service draughts and modes.In order to determine VCG of the actual loading conditions, the lightweight and its centre of gravity shall beknown. This shall be obtained by an inclining test carried out in accordance with IMO MODU Code, 2009.

Table 3

Description Reference

Determination of Lightweight IMO MODU Code, 2009, Regulation 3.1

Determination of wind forces: IMO MODU Code, 2009, Regulation 3.2

Intact Stability Requirements: IMO MODU Code, 2009, Regulation 3.3

Damage Stability Requirements: IMO MODU Code, 2009, Regulation 3.4 1), 2)

1) The internal subdivision shall be adequate to enable the unit or installation to comply with the damage stabilityrequirements

2) The following permeability factors shall be assumed in the calculations:

— Store rooms: 0.60— Engine room: 0.85— Tanks, void spaces etc: 0.95

Other permeabilities may be accepted if documented by calculations.

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Loading computers for stability calculation shall be considered as supplementary to the stability manual orthe stability part of the operation manual. If onboard computers for stability calculations are installed, thesesystems shall be approved in accordance with requirements in DNV rules for ships Pt.6 Ch.9.

3 Watertight integrity, freeboard and weathertight closingappliances

3.1 GeneralWatertight closing appliances are required for those external openings being submerged at least up to anangle of heel equal to the first intercept in intact or damage condition, whichever is greatest.Weathertight closing appliances are required for those external openings being submerged at least up to anangle of heel equal to the dynamic angle. This applies to any opening within 4.0 m above the final waterlineas well.Ducts or piping, which may cause progressive flooding in case of damage, shall generally not be used in thedamage penetration zone.Location of openings where watertight and weathertight integrity are required, are illustrated in DNVGL-OS-C301 Ch.2 Sec.2 [10].The requirements for operation and locking of doors and hatch covers are given in DNVGL-OS-C301 Ch.2Sec.2 [10].For testing of doors and hatch covers ref. DNVGL-OS-C301 Ch.2 Sec.2 [9].

3.2 MaterialsMaterials and material certificates for:

— rolled steel for structural applications and pressure vessels— steel tubes, pipes and fittings— steel forgings— steel castings— aluminium alloys,

shall comply with the requirements given by DNVGL-OS-B101 unless otherwise stated in the relevanttechnical reference documents.Stainless steel shall be with a maximum carbon content of 0.05%. The stainless steel material shall be of thewhite pickled and passivated condition. Aluminium shall be of seawater resistant type.

3.3 Watertight integrityThe number of openings in watertight subdivisions shall be kept to a minimum compatible with the designand proper working of the unit or installation. Where penetrations of watertight decks and bulkheads arenecessary for access, piping, ventilation, electrical cables etc., arrangements shall be made to maintain thewatertight integrity of the enclosed compartments.Piping and electrical systems for operation of watertight closing appliances shall be in accordance withrelevant requirements given in DNVGL-OS-D101 unless otherwise specified in this section.The strength and arrangement of sliding doors and hatch covers and their frames as well as the capacity ofthe closing systems shall be sufficient to ensure efficient closing of doors and hatch covers when water with ahead of 2.0 m is flowing through the opening, and at an inclination of 17° in any direction.In addition watertight integrity shall comply with the details DNVGL-OS-C301 Ch.2 Sec.2 as given in Table 4.

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Table 4


Internal openings DNVGL-OS-C301 Ch.2 Sec.2 [3.2]

External opening DNVGL-OS-C301 Ch.2 Sec.2 [3.3]

Strength of watertight doors and hatch covers DNVGL-OS-C301 Ch.2 Sec.2 [3.4]

Frame and bulkhead interface DNVGL-OS-C301 Ch.2 Sec.2 [3.5]

Operation and control of watertight doors and hatch covers DNVGL-OS-C301 Ch.2 Sec.2 [3.6]

3.4 Weathertight closing appliancesThe closing appliances shall in general have a strength at least corresponding to the required strength of thepart of the hull in which they are fitted. For side scuttles and windows, however, the pressure head shall notbe taken less than 2.5 m water column.

Guidance note:

Some requirements are also governed by the regulations in the «International Convention of Load Lines 1966»:

— doors in reg.12

— definition of positions in reg.13

— hatchways in reg.14 to reg.16

— machinery space openings in reg.17

— miscellaneous openings in reg.18

— ventilators in reg.19

— air pipes in reg.20

— scuppers, inlets and discharges in reg.22

— side scuttles in reg.23

— freeing ports in reg.24

— special requirements in reg.25 to reg.27.


Requirements for specific closing appliances is given in DNVGL-OS-C301 Ch.2 Sec.1 and DNVGL-OS-C301Ch.2 Sec.2 as listed in Table 5.

Table 5

Description Reference in DNVGL-OS-C301

Chain lockers DNVGL-OS-C301 Ch.2 Sec.1 [5.8]

Weathertight doors DNVGL-OS-C301 Ch.2 Sec.2 [4.2]

Weathertight hatch coamings and covers DNVGL-OS-C301 Ch.2 Sec.2 [4.3]

Gaskets and closing devices DNVGL-OS-C301 Ch.2 Sec.2 [4.4]

Drainage arrangement DNVGL-OS-C301 Ch.2 Sec.2 [4.5]

Buckling check DNVGL-OS-C301 Ch.2 Sec.2 [4.6]

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3.5 FreeboardLoad lines for self-elevating units are calculated under the terms of the ILLC 1966. When floating or whenin transit from one operational area to another, the units shall be subject to all the conditions of assignmentof the ILLC 1966 unless specifically accepted. The regulations of relevant national authorities shall also beobserved.Draught marks shall be located in positions, which will ensure accurate determination of draughts, trim andheel and where they are clearly visible to personnel operating the unit or installation. The reference line shallbe defined in the stability manual.Self-elevating units or installations shall not be subject to the terms of the ILLC 1966 while they aresupported by the seabed or are in the process of lowering or raising their legs.The minimum freeboard of units or installations, which cannot be computed by the normal methods laiddown by the ILLC 1966, shall be determined on the basis of meeting the applicable intact stability, damagestability and structural requirements for transit and operational conditions while afloat. The freeboard shallnot be less than that calculated in accordance with the ILLC 1966, where applicable.Self –elevating units may be manned when under tow. In such cases a unit is subject to the bow heightrequirement as given in Regulation 39 (1) of the International Convention on Load Line. The requirementmay not always be possible to achieve. With reference to MODU Code 3.7.18 the owner should apply tothe flag administration for an exemption from the bow height requirement, having regard to the occasionalnature of such voyages on predetermined routes and to prevailing weather conditions.”

3.6 PenetrationsSide scuttles below freeboard deck shall be of the non-opening type with inside hinged deadlight.Other relevant requirements on penetrations are given in DNVGL-OS-C301 Ch.2 Sec.2 as given in Table 6.

Table 6


Ventilators and air pipes DNVGL-OS-C301 Ch.2 Sec.2 [6]

Inlets, discharges and scuppers DNVGL-OS-C301 Ch.2 Sec.2 [7]

Side scuttles and windows DNVGL-OS-C301 Ch.2 Sec.2 [8]

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SECTION 3 TOWING

1 General

1.1 IntroductionThis section provides requirements for towing.Table 1 lists references required for a complete understanding of this chapter.


Reference Title


DNVGL-OS-E301 Position mooring

DNVGL-OS-E304 Offshore mooring steel wire ropes

DNV-RP-C205 Environmental Conditions and Environmental Loads

1.2 Plans and data to be submittedA general overview of the content of the plans and analyses is listed in Table 2. A more detailed overview,tuned to the specific design and project scope can be obtained from DNV GL’s Nauticus Production System.



H050 – Structural drawing

including towing force design loads and winch loadfootprint.Applicable if static force > 50 kN or bending moment >100 kNm.

APPassive towingequipmentsupporting structures

H080 – Design analyses Applicable if static force > 50 kN or bending moment >100 kNm FI


1.3 PrinciplesSelf-elevating units shall have arrangement and devices for towing. Requirements for towing systemsare given in DNVGL-OS-E301 Ch.2 Sec.4 [16] and DNVGL-OS-E301 Ch.3 Sec.2 [11]. Requirements forequipment are given in DNVGL-OS-E304.Non-self propelled self-elevating units are not required to have temporary mooring.

2 Detailed requirements

2.1 GeneralThe unit shall have a permanent arrangement for towing. The line between the fastening devices and thefairlead shall be unobstructed.

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There shall be arrangements for hang-off and retrieval of the unit's towing bridle(s) and towing pennant(s).In addition to the permanent towing arrangement, there shall be a possibility of using an emergencyarrangement of equivalent strength. Application of the unit's mooring arrangement may be considered forthis purpose.The design load for the towing arrangement shall be clearly stated, e.g. for classed units, in the appendix tothe classification certificate.

2.2 MaterialPlate materials in towline fastening devices and their supporting structures shall be as given in Table 3 inDNVGL-OS-C101 Ch.2 Sec.3, or DNVGL-OS-C102 Ch.2 Sec.3.The termination of towing bridle(s) and/or pennant(s) where connected to the unit should be chain cableof sufficient length to ensure that steel wire rope segments of the towing arrangement will not be subjectto chafing against the unit for towline pull sector between 90° port and 90° starboard. Alternatively the fulllength of bridle(s) and pennant(s) can be chain cable.Chain cables and shackles to be used in the towing arrangement shall be of offshore quality (R3, R3S, R4,R4S or R5) or ship chain quality K3. Green pin type shackles of polar type may be accepted provided they arecertified by DNV GL.Towing bridles and pennants of steel wire rope shall be in accordance with the requirements given in DNVGL-OS-E301 respectively DNVGL-OS-E304.All eyes in towing arrangement connections shall be fitted with hard thimbles or spelter sockets in accordancewith DNVGL-OS-E301 Ch.2 Sec.4 [14].

2.3 Strength analysisThe design load for the towing arrangement shall be based on the force, FT, required for towing the unitwhen floating in its normal transit condition. For the purpose of determining the required towing force,thrust provided by the unit's own propulsion machinery should normally not be taken into account. The unitunder tow shall be able to maintain position against a specified sea state, wind and current velocity actingsimultaneously, without the static force in the towing arrangement exceeding its towing design load.As a minimum the following weather conditions shall be used for calculation of environmental drift forces, FT,for world-wide towing:

— sustained wind velocity: U1 min, 10 = 20 m/s (10 m above sea level)— current velocity: VC = 1 m/s— significant wave height: HS = 5 m— zero up-crossing wave period in second: 6 ≤ Tz ≤ 9.

Guidance note:

Environmental forces may be calculated according to DNV-RP-C205. A self-elevating unit is not free to be towed world-wide, i.e.the environmental conditions – as specified by the designer – are not to be exceeded.

The above formula for FT is pending on that designer specified input for wave, current and loads is lower than above


Normally the towing arrangement shall be designed for use of a single tug of sufficient capacity. If the size ofthe unit necessitates the use of two or more tugs pulling in the same direction, the towing design load, FD, tobe used in the strength analysis for each towing bridle or pennant is a function of the required towing forceand the number of tugs comprised in the design and given by:

where:ftow = design load factor

= 1.0, if NTUG = 1

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= 1.5/NTUG, if NTUG > 1NTUG = number of tugs comprised in the design of the towing arrangement.

Guidance note:

It is advised that the towing design load for each towing bridle or pennant not to be taken less than 1000 kN and that the towingarrangement is designed for use of a single tug.


The minimum breaking strength, Smbs of the unit's towing bridle(s) and/or towing pennant(s), shall not beless than 3 times the towing design load, FD.The nominal equivalent stress, σe in the flounder plate is normally not to exceed σf when subjected to a loadequal to the breaking strength of the unit's towline, Smbs. The strength analysis shall be made for the mostunfavourable direction of the towline.Towing fastening devices, including fairleads, and their supporting structures shall be designed for a loadequal to the minimum breaking strength of the weakest link in the unit's towing bridle and/or towingpennants, Smbs. Strength analyses shall be made for the most unfavourable direction of the towline pull,i.e. angle of attack to device or structure. The nominal equivalent stress, σe, in the towing devices and theirsupporting structures shall not exceed 0.9 σf and 0.8 σf, respectively.

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CHAPTER 5 MACHINERY SYSTEMS AND EQUIPMENT

SECTION 1 MARINE, MACHINERY AND PIPING SYSTEMS

1 General

1.1 IntroductionThis section provides principles, technical requirements and guidance for design, manufacturing andinstallation of marine and machinery systems.Table 1 lists references required for a complete understanding of this chapter.


Reference Title

IMO Res. A.753(18) Guidelines for the application of plastic pipes on ships

DNVGL-OS-B101 Metallic materials



DNV rules for ships Pt.4 Ch.3 Rotating Machinery, Drivers

DNV rules for ships Pt.4 Ch.4 Rotating Machinery, Power Transmission

DNV classification Note 41.2 Calculation of Gear Rating for Marine Transmission

1.2 ApplicationThese rules apply to marine piping systems, machinery piping systems and marine machinery systems. Theydo not include systems primarily intended for operation in drilling or hydrocarbon production service and theirdedicated auxiliary systems. Interfaces between such systems and marine systems should be identified and aspecification break defined.

Guidance note:

Piping and equipment for drilling and drilling related auxiliary systems are addressed in DNVGL-OS-E101. These are only part ofclass scope if the additional class notation DRILL has been included in the contractual agreement between yard and DNV GL.


1.3 Plans and data to be submittedPlans showing machinery arrangement shall be submitted for information. These shall show layout ofmachinery components such as engines, boilers, fans, heat exchangers, generators, switchboards, pumps,purifiers, filters etc., but excluding pipes, valves and accessories.The plans shall be accompanied by a list of the components and specification of make and type.A general overview of the required plans and analyses is listed in Table 2. A more detailed overview, tuned tothe specific design and project scope can be obtained from DNV GL’s Nauticus Production System.

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C040 – Design analysis Axial vibration calculations AP

C040 – Design analysis Torsional vibration calculations for transientconditions APMain generator diesel engine

(main/emergency)

C040 – Design analysisTorsional vibration calculations for steadystate conditions. Applicable for engine ratedpower ≥ 500 kW

AP

C040 – Design analysis

Engine vibration calculations. Applicable forengine rated power ≥ 200 kW. Applicable forresilient mounted engine, except generatordriver set rigidly mounted on a resilientmounted frame

AP

Main generator diesel engine→ Resilient engine mount

C040 – Design analysis

Calculations of the static and dynamicposition within the elastic mounts includingtype designation and fastening arrangementdrawing

AP

Machinery and marine pipingsystems general

S050 – Connections to theshell and to sea chests Sea valves AP

Valve control hydraulic powersystem S040 – Control diagram Remote control of valves AP

Auxiliary feed water system S011 – Piping diagram AP

Auxiliary steam piping system(hot water) S011 – Piping diagram AP

Auxiliary condensate system AP

Fuel oil system AP

Lubrication oil system AP

Quick closing valvearrangement AP

Fresh water system Cooling system AP

Compressed air systems AP

Internal drain arrangements AP

Scuppers AP

Sounding systems AP

Overflow system AP

Exhaust systems If outlets are through ships side or stern AP

Provisions refrigerationsystem

S011 – Piping diagram

AP

S011 – Piping diagram APSludge handling arrangementBilge handling systems S030 – Capacity analysis AP

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S011 – Piping diagramSea water systemBallast system Z170 – Installation manual Plastic pipes only AP

Sea chests S050 – Connections to theshell and to sea chests Sea valves AP


Air pipes S020 – Pressure dropanalysis Back pressure in tanks when overfilling AP

Fuel oil control andmonitoring system

Lubrication oil control andmonitoring system

Sea water control andmonitoring system

Fresh water control andmonitoring system

Starting air control andmonitoring system

Control air control andmonitoring system

Bilge water control andmonitoring system

Ballasting control andmonitoring system

I020 – Control andmonitoring systemdocumentation

Control of valves and pumps AP

For general requirements to documentation, including definition of the codes and documentation types, seeDNVGL-RU-SHIP Pt.1 Ch.3.For pipes conveying steam with a temperature exceeding 400°C, the plans shall show particulars offlanges and bolts and details of welded joints with specification of welding procedure and filler metals. Forcalculations of thermal expansion stresses see DNVGL-OS-D101 Ch.2 Sec.2 [3.5].Detailed information on the installation procedures for plastic pipes shall be submitted for approval. Thedocumentation shall include information on joining procedure, supporting, clamping and expansion elements.

2 Principles

2.1 GeneralThe machinery shall be so arranged that inadvertent operation leading to reduced safety of the unit orinstallation or personnel, cannot occur as a consequence of one single operational error.The machinery and piping systems shall be arranged to prevent sea water, stored hydrocarbons or chemicalsor ballast from reaching dry spaces of the installation or stored hydrocarbons or chemicals from beingdischarged overboard as a consequence of inadvertent operations. Measures shall also be taken to preventinadvertent movement of ballast or stored fluids internally within these systems.Systems and tanks shall be so arranged that leakage or operation of valves will not directly lead to increasedrisk of damage to machinery, installation or personnel due to mixing of different fluids.

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Machinery, boilers and associated piping systems shall be so installed and protected as to reduce to aminimum any danger to persons onboard, due regard being paid to moving parts, hot surfaces and otherhazards.Units or installations with ballast water treatment systems installed in order to meet the requirements of theballast water management convention shall follow the requirements of DNV rules for ships Pt.6 Ch.18 Sec.4.

2.2 Component designWhere no specific requirements are given in these standards regarding dimensioning and choice of materials,generally recognized standards and engineering principles may be applied.If acceptable accuracy cannot be obtained by strength calculations, special tests for the determination of thestrength of the design may be required.When it is of essential significance for the safety of the unit or installation that the function of a component ismaintained as long as possible in the event of fire, materials with high heat resistance shall be used.Materials with low heat resistance shall not be used in components where fire may cause outflow offlammable or health hazardous fluids, flooding of any watertight compartment or destruction of watertightintegrity.

Guidance note:

Materials with high heat resistance are materials having a melting point greater than 925°C. Materials with low heat resistance areall other materials. Deviations from the above requirement will be subject to special considerations.


3 Valves

3.1 Design and testsRequirements regarding the design of valves are given in DNVGL-OS-D101 Ch.2 Sec.2 [5.1]. Requiredhydrostatic tests are described in DNVGL-OS-D101 Ch.2 Sec.2 [5.2].

3.2 InstallationRequirements regarding the installation of valves are given in DNVGL-OS-D101 Ch.2 Sec.1 [1.8].

3.3 OperationOpen or closed position of valves shall be easily visible. If a valve's function in the system is not evident,there shall be adequate information on a name plate attached to the valve. Other requirements regarding theoperation of valves are given in DNVGL-OS-D101 Ch.2 Sec.1 [1.7].

4 Piping

4.1 DesignMarine piping systems include the following:

— ballast system— bilge system— drains system— air/overflow systems— sounding system— cooling system— lubricating oil system— fuel oil system

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— thermal oil system— feed water and condensate systems— steam system— hydraulic system— pneumatic system— firewater system.

Piping systems used for safe operation of the unit or installation shall in general be separate from pipingsystems used for drilling or production operations. If cross connections are necessary, appropriate meansshall be fitted to prevent possible contamination of the safe system from any hazardous medium.Installation of pipes for water, steam or oil behind or above electric switchboards shall be avoided as far aspossible. If this is impracticable, all detachable pipe joints and valves shall be at a safe distance from theswitchboard or well shielded from it.Routing of water pipes and air and sounding pipes through freezing chambers shall be avoided.For water-cooled electrical equipment seawater pipes shall be routed away from the equipment, so that anyleakage in flanges do not damage the equipment.

4.2 MaterialsMaterials used in piping systems shall be suitable for the medium and service for which the system isintended. The following aspects should be considered when selecting materials:

— type of service— compatibility with other materials in the system such as valve bodies and casings, for example in order to

minimize bimetallic corrosion— ability to resist general and localized corrosion or erosion caused by internal fluids and/or marine

environment— ability to resist selective corrosion, for example de-zincification of brass, de-aluminification of aluminium

brass and graphitization of cast iron— ductility— need for special welding procedures— need for special inspection, tests, or quality control.

Guidance note:

The traditional stainless steels, including type 316 or 316L, are generally not considered suitable for use in seawater systems.

However, certain stainless steels with higher contents of chromium, molybdenum and nitrogen have improved resistance tolocalised corrosion. These include high molybdenum austenitic steels and ferritic-austenitic (duplex) steels. Even these steelscannot be considered immune to attack under all situations; avoidance of stagnant seawater conditions and removal of weldingoxides are some of the important factors to the successful use.


Materials to be used in the construction of piping systems shall be manufactured and tested in accordancewith DNVGL-OS-B101. Carbon steel materials are in general suitable for the majority of the piping systems.Galvanised pipes are recommended as the minimum protection against corrosion for pipes in seawatersystems, including those for bilge, air vent and ballast service.Non-ferrous metallic materials may be accepted in piping system transporting flammable fluids and in bilgepiping provided that fire endurance properties in accordance with a recognised code is documented.In addition to the above, additional details are given in DNVGL-OS-D101 Ch.2 Sec.2 as listed in Table 3.

Table 3

Description Reference in DNVGL-OS-D101

Carbon and low alloy steel DNVGL-OS-D101 Ch.2 Sec.2 [2.2]

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Copper and copper alloys DNVGL-OS-D101 Ch.2 Sec.2 [2.3]

Cast iron DNVGL-OS-D101 Ch.2 Sec.2 [2.4]

Plastic pipes DNVGL-OS-D101 Ch.2 Sec.2 [2.5]

Flanges, valve bodies, etc. DNVGL-OS-D101 Ch.2 Sec.2 [2.6]

Bolts and nuts DNVGL-OS-D101 Ch.2 Sec.2 [2.7]

Material certificates DNVGL-OS-D101 Ch.2 Sec.2 [2.8]

4.3 Platform piping

4.3.1 Pre-load/ballastThe rig shall be supplied with a ballast/pre-load system with redundant pumping capability. Dump valves areaccepted for drainage of the pre-load tanks.In addition, the general requirements of DNVGL-OS-D101 Ch.2 Sec.3 as listed in Table 4 shall be compliedwith.

4.3.2 Bilge and drainageThe unit or installation shall be equipped with 100% redundancy in bilge pumping system and means fordraining engine room, all compartments and watertight sections. Compartments containing liquids such ascooling water, oil fuel or stored produced liquid shall have their own separate pumping system.Again, the general requirement in DNVGL-OS-D101 Ch.2 Sec.3 as listed in Table 4 shall be complied with.

Table 4


Basic requirements DNVGL-OS-D101 Ch.2 Sec.3 [2.1]

Ballast systems DNVGL-OS-D101 Ch.2 Sec.3 [2.2]

Drainage of dry compartments below main deck DNVGL-OS-D101 Ch.2 Sec.3 [2.3]

Drainage of dry compartments above main deck DNVGL-OS-D101 Ch.2 Sec.3 [2.4]

Pumping and piping arrangement DNVGL-OS-D101 Ch.2 Sec.3 [2.5]

Bilge pipes DNVGL-OS-D101 Ch.2 Sec.3 [2.6]

Bilge pumps DNVGL-OS-D101 Ch.2 Sec.3 [2.7]

Bilge wells, mud boxes, valves etc. DNVGL-OS-D101 Ch.2 Sec.3 [2.8]

4.3.3 Raw water systemsIf the raw water system supplies water to essential systems, such as fire water systems or cooling water,system and installation requirements shall be as required for the essential system.The following raw water system requirement applies:

1) A suitable isolation valve/valves to be provided to be able to isolate one of raw water pump systems2) In case of leg well suction, hoses may be permitted provided they are adequately supported. Hoses to be

fire protected according IMO Res. A.753(18) L3 and protected from relevant fire scenarios1) except whena single incident will not impair the required raw water capacity.

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3) Suction points (if both is fitted on one leg) to be at different heights (or caissons to be adequatelyprotected).

Guidance note:

Submersible raw water pumps installed on a hose reel may be considered case to case. The hose reel to be located to ensure thata single incident would not damage both. Collapsible type hoses are not considered acceptable. The fire resistance of hoses as forleg well suction.


4.3.4 Drag chainsHoses in drag chain shall be fire protected according IMO Res. A.753(18) L3 and protected from relevant firescenarios1).

1) Reference is made to USCG PFM 1-98: Policy File Memorandum on the Fire Performance Requirementsfor Plastic Pipe per IMO Resolution A.753(18).

4.3.5 Air, overflow and soundingAir, overflow and sounding shall be installed according DNVGL-OS-D101 Ch.2 Sec.3 [6] as detailed in Table 5.

Table 5


Arrangement of air pipes DNVGL-OS-D101 Ch.2 Sec.3 [6.1]

Air pipes, sectional area DNVGL-OS-D101 Ch.2 Sec.3 [6.2]

Overflow pipes, arrangement DNVGL-OS-D101 Ch.2 Sec.3 [6.3]

Overflow pipes, sectional area DNVGL-OS-D101 Ch.2 Sec.3 [6.4]

Sounding arrangements DNVGL-OS-D101 Ch.2 Sec.3 [6.5]

Sounding pipes, sectional area DNVGL-OS-D101 Ch.2 Sec.3 [6.6]

4.3.6 Storage and transfer systems for helicopter fuelsIf installed, tanks and pipe systems for the storage and transfer systems for helicopter fuels have to complyto DNVGL-OS-D101 Ch.2 Sec.3 [7].

4.4 Machinery piping

4.4.1 GeneralRedundancy capacity of components shall be as specified in the requirements for the different systems.Applied to piping systems this implies that more than one pump unit shall be installed when failure of such aunit will result in loss of a main function.The capacity shall normally be sufficient to cover demands at maximum continuous load on the main functionwhen any pump unit is out of service.

4.4.2 Cooling systemCooling systems in self-elevating units or installations shall be so arranged that the supply of cooling water tothe generator prime movers will not be affected during raising and lowering of the installation, even if the firepumps are in operation. In such events the cooling water may be supplied from a storage tank.More detailed requirements are given in DNVGL-OS-D101 Ch.2 Sec.4 [2].

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4.4.3 Lubrication oil systemLubricating oil systems shall be separated from other systems. This requirement does not apply to hydraulicgoverning and manoeuvring systems for auxiliary engines.Other requirements are given in DNVGL-OS-D101 Ch.2 Sec.4 [3] as detailed in Table 6.

Table 6


Lubricating oil pre-treatment arrangement DNVGL-OS-D101 Ch.2 Sec.4 [3.2]

Lubricating oil supply DNVGL-OS-D101 Ch.2 Sec.4 [3.3]

Remote shut-off arrangement for lubricating oil tanks DNVGL-OS-D101 Ch.2 Sec.4 [3.4]

4.4.4 Fuel oil systemRequirements for the fuel oil system are given in DNVGL-OS-D101 Ch.2 Sec.4 [4], as detailed in Table 7.

Table 7


Flash point of fuel oil DNVGL-OS-D101 Ch.2 Sec.4 [4.1]

Fuel oil tanks DNVGL-OS-D101 Ch.2 Sec.4 [4.2]

Fuel oil piping DNVGL-OS-D101 Ch.2 Sec.4 [4.3]

Arrangement of valves and fittings DNVGL-OS-D101 Ch.2 Sec.4 [4.4]

Remotely controlled shut-off arrangement for fuel oil tanks DNVGL-OS-D101 Ch.2 Sec.4 [4.5]

Fuel oil pre-heaters DNVGL-OS-D101 Ch.2 Sec.4 [4.6]

Fuel oil pre-treatment arrangement DNVGL-OS-D101 Ch.2 Sec.4 [4.7]

Drip trays DNVGL-OS-D101 Ch.2 Sec.4 [4.8]

Oil filters DNVGL-OS-D101 Ch.2 Sec.4 [4.9]

Various requirements DNVGL-OS-D101 Ch.2 Sec.4 [4.10]

4.4.5 Feed water and condensation systemsRequirements for the feed water and condensation system are given in DNVGL-OS-D101 Ch.2 Sec.4 [6], asdetailed in Table 8.

Table 8


Feed water pumps and piping DNVGL-OS-D101 Ch.2 Sec.4 [6.1]

Feed water heating DNVGL-OS-D101 Ch.2 Sec.4 [6.2]

Feed water tanks DNVGL-OS-D101 Ch.2 Sec.4 [6.3]

Condensate from steam heating of tanks DNVGL-OS-D101 Ch.2 Sec.4 [6.4]

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4.4.6 Hydraulic systemsThe redundancy requirement of the top of the section applies to pumps, filters and pressure reduction units.Other requirements are given in DNVGL-OS-D101 Ch.2 Sec.4 [8], as detailed in Table 9.

Table 9


General DNVGL-OS-D101 Ch.2 Sec.4 [8.1]

Hydraulic power supply DNVGL-OS-D101 Ch.2 Sec.4 [8.2]

Hydraulic cylinders DNVGL-OS-D101 Ch.2 Sec.4 [8.3]

Accumulators DNVGL-OS-D101 Ch.2 Sec.4 [8.4]

Hydraulic equipment DNVGL-OS-D101 Ch.2 Sec.4 [8.5]

4.4.7 Pneumatic power supplyThe redundancy requirement on the top of this section applies for compressors, filters, pressure reductionunits when supplying power for control of main functions, and air treatment units (lubricator or oil mistinjector and dehumidifier.Other requirements on the power supply and the pneumatic equipment are given in DNVGL-OS-D101 Ch.2Sec.4 [9].

4.5 Pipe fabrication, workmanship and testingFabrication, workmanship and testing of piping is described in DNVGL-OS-D101 Ch.2 Sec.6, as detailed inTable 10.

Table 10


Welding DNVGL-OS-D101 Ch.2 Sec.6 [2]

Brazing of copper and copper alloys DNVGL-OS-D101 Ch.2 Sec.6 [3]

Pipe bending DNVGL-OS-D101 Ch.2 Sec.6 [4]

Joining of plastic pipes DNVGL-OS-D101 Ch.2 Sec.6 [5]

Hydrostatic tests of piping DNVGL-OS-D101 Ch.2 Sec.6 [6]

Functional testing DNVGL-OS-D101 Ch.2 Sec.6 [7]

5 Rotating machines

5.1 PrinciplesThe machinery shall be so designed, installed and protected that risks of fire, explosions, accidental pollution,leakages and accidents thereof are acceptably low.Reliability and availability of the machinery shall be adapted according to considerations of the consequencesfrom machinery failures and disturbances.

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The design arrangement of machinery foundations, shaft connections, piping and ducting shall take intoaccount the effects of thermal expansion, vibrations, misalignment and hull interaction to ensure operationwithin safe limits. Bolts and nuts exposed to dynamic forces and vibrations shall be properly secured.It should be ensured that the design of the bearings and the arrangements for lubrication are satisfactoryto withstand the inclinations specified in Ch.2 Sec.3 [3]. The manufacturer should be informed when themachine is ordered.

5.2 Diesel enginesRequirements for diesel engines used for main and emergency power, including the related proceduralrequirements for certification and testing are described in DNV rules for ships Pt.4 Ch.3 Sec.1 as detailed inTable 11.

Table 11

Description Reference in DNV rules for ships Pt.4 Ch.3 Sec.1

General A

Design B

Testing and Inspection C

Workshop Testing D

Control and Monitoring E

Arrangement F

Vibration G

Installation Inspections H

Shipboard Testing I

5.3 Starting arrangements

5.3.1 CapacityStarting systems for internal combustion engines (excluding emergency generators) shall have capacity for3 starts each. The duration of each starting shall be minimum 10 s. If a starting system serves two or moreengines, the capacity of the system shall be the sum of the capacity requirements.Additional requirements to the starting system for generator sets arranged as standby generators and/orarranged for starting in a black-out situation are given in Sec. 2[1].Requirements to starting of emergency generators are given in [5.3.4]. Drivers for fire pumps required to befed from emergency generator shall follow the same starting requirements as for emergency generators.

5.3.2 PneumaticCompressors shall be installed with total capacity sufficient for charging air receivers of capacities specifiedabove from atmospheric to full pressure in the course of one (1) hour.Two or more compressors of total capacity as specified above shall be installed. The capacity shallbe approximately equally shared between the compressors. At least one of the compressors shall beindependently (not direct connected to the engine) driven.Engines started by compressed air shall have at least two independent starting air receivers of about equalcapacity.

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In order to protect starting air mains against explosion arising from improper functioning of starting valve,the following devices shall be fitted:

— an isolation non-return valve or equivalent at the starting air supply connection to each engine— a bursting disc or flame arrester in way of the starting valve of each cylinder for direct reversing engines

having a main starting manifold— at the supply inlet to the starting air manifold for non-reversing engines.

The bursting discs or flame arresters may be omitted for engines having a bore not exceeding 230 mm.The pipes and valves, including the non-return valve, shall be designed to withstand the possible backpressure if a starting valve remains open.Use of flexible hoses in the starting air system is only permitted where necessary in order to allow for relativemovements. Flexible hoses with their couplings shall be type approved.

5.3.3 ElectricWhen electric starting arrangement for auxiliary engines is used, there shall be at least two separatelyinstalled batteries, connected by separate electric circuits arranged such that parallel connection is notpossible. Each battery shall be capable of starting the engine when in cold and ready to start condition.Starting arrangements for two or more main engines shall be divided between the two batteries andconnected by separate circuits.The batteries shall be installed in separate boxes or lockers or in a common battery room with separateshelves (not above each other).The capacity of starting batteries shall comply with capacity requirements as given on the beginning of thissection. If the starting batteries are also used for supplying other consumers, the capacity shall be increasedaccordingly.

5.3.4 Emergency generatorsEmergency generating set shall be equipped with starting device with a stored energy capability of at leastthree consecutive starts. A second source of energy shall be provided for an additional three starts within 30minutes, unless manual starting can be demonstrated to be effective within this time.If the emergency generator is arranged for pneumatic starting, the air supply shall be from a separate airreceiver.The air receiver shall not be connected to other pneumatic systems, except for the starting system in theengine room. If such a connection is arranged, the pipeline shall be provided with a screw-down non-returnvalve.

5.4 Start from “dead ship”«Dead ship» condition as defined in the MODU Code Ch.1.3.15 implies for non-self propelled Self Elevatingunits that main power supply is out of operation and that auxiliary services (such as compressed air, startingcurrent from batteries etc.) for the restoration of the main power supply are not available.From the above condition, the main power supply shall be brought back in operation within 30 minutes usingonly the facilities available on board. In addition, it shall be possible to recover from a dead ship conditionwith any one generator, transformer or power converter out of service.The emergency source of electrical power may be used for the purpose of starting from a dead ship conditionif its capability either alone or combined with that of any other source of electrical power is sufficient toprovide at the same time those services required to be supplied from the emergency power, except firepumps. (see MODU Code 7.9.1.2, for a list of the services see DNVGL-OS-D201 Ch.2 Sec.2 [3.1.3]).

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6 Jacking system

6.1 General

6.1.1 ApplicationThe requirements in this section are specific for installations of the pinion rack type.This section focuses on the requirements as relevant for the yard. The requirements relevant for the jackinggear vendor are detailed in DNVGL-OS-D101 Ch.2 Sec.5 [3].The jackhouse frame, fixation system and the welding connection between rack and leg structure are dealtwith in DNVGL-OS-C104 Ch.2 Sec.4 [2] and DNVGL-OS-C201 Ch.2 Sec.11 [7] and is further discussed inSec.1 of these rules.

6.1.2 Document and plans to be submittedIn general detailed information to assess the quality of the jacking gear system is supplied by its vendor.A list of the expected information is given in DNVGL-OS-D101 Ch.3 Sec.1 [4].The yard shall specify a relevant load-time spectrum. This shall include at least the following:

— raising of the legs— lowering of the legs— raising of the platform— lowering of the platform— exceptional use (e.g. one or more units out of service)— pre-load holding (static)— pre-load raising (if permitted)— pre-load lowering— storm holding (static)— motor stalling torque.

The elements in the load-time spectrum listed above (except motor stalling torque) are vertical net loads onthe rack.The following shall be included in the load spectrum:

— friction losses from leg guiding in the hull structure— effect of variation in location of the centre of gravity of the unit or installation.

Unless otherwise documented, the guide friction may be taken as 10% of the net vertical force in normaloperation. When lifting in a tilted position (due to soil penetration in pre-load) higher guide friction shall beassumed. When evaluating the stresses in the jacking machinery, the influence of friction in bearings and ongear flanks shall be considered.An failure mode and effect analysis (FMEA) according to DNVGL-OS-D202 Ch.3 Sec.1 Table 4 shall be carriedout.

6.2 Design principlesAll jacking machinery components shall be designed for any relevant load condition mentioned above. Designsafety factors etc. are valid for all foreseen operating conditions. For loads that are not foreseen, but mayoccur, such as motor stalling torque, lower safety factors may apply.When a design is documented by means of tests in lieu of calculations, or by combinations thereof, lowersafety factors than those required by calculations may be accepted. The level will be considered on the basisof the extent of the testing and the acceptance criteria for the various parts after the test. When units orparts of units are tested, normally the whole load spectrum shall be applied and each load level shall bemultiplied with the required safety factor. When different safety factors apply, such as for tooth root strength

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and flank durability, the highest (i.e. tooth root strength) shall be used for testing purposes. (Due to theelevated loads, some flank deterioration is considered acceptable in this case).Jacking mechanisms shall be arranged so that a single failure of any component does not cause anduncontrolled descent of the unit (ref. MODU Code 4.14.1).If the system does not include a fixation system, the pinion, gearbox and motor shaft shall be considered asstructural components. Design shall hence be in line with principles in standards referenced under Table 1.

6.3 MaterialsGeneral requirements are given in Ch.3.Materials in forged and cast components shall satisfy the requirements given in DNVGL-OS-B101 Ch.2 Sec.3Table 3 and DNVGL-OS-B101 Ch.2 Sec.4 Table 2. For materials with yield strength value higher than given inthe table, the material properties are equal to the highest tabulated values. Materials in fixation chocks in thefixation system (if installed) shall be equivalent to the material in the racks.

6.4 ArrangementThe jacking units shall be arranged so that they can be removed individually for servicing.The jacking system shall be arranged in such a way that visual monitoring during jacking is possible, thisincludes the fixation system.In case of single failures, the jacking systems shall be designed such that repair (incl. minor replacements) ispossible within 3 hours.The jacking units shall be supported in such a way that elastic jack-house frame deflections are not harmfulto the pinion-rack mesh.The jacking machinery with control system is defined as an important system as defined in DNVGL-OS-D202Ch.1 Sec.1 [3.2.10].Chock pad properties shall be documented. Extent of additional documentation to be determined by FMEAand novelty of design. Possibilities for replacement of these flexible mountings shall be taken into account.Flexible (sandwich) rubber pads shall be protected by an oil based coating.The jack-house frame and leg-rack shall have dimensional tolerances that permits an involute gear mesh (i.e.contact ratio is above unity) between pinion and rack under all operating conditions.

6.5 Electrical systemsPrinciples, technical requirements and guidance for design, manufacturing and installation of electricalinstallations, shall be in accordance to Sec.2 and be classified as an important system in line with [6.4].Power supply shall be arranged so that no single failure prevents the jacking operation.

6.6 Control and monitoringThe control and monitoring system shall be in accordance with R3 requirements described in DNVGL-OS-D202, and be classified as an important system. General requirements in DNVGL-OS-D202 will apply.In case of failure in the control system, jacking operations shall be stopped or fail to a safe position.Emergency stop of jacking operation shall be possible from the vicinity of the central jacking control station.Emergency stop circuit shall be independent of the control system and failure in the circuit shall be alarmed.The jacking system should be operable from a central jacking control station.(ref. MODU code 4.14.2).A communication system should be provided between the central jacking control and a location at each leg.(ref. MODU code 4.14.4).The jacking system shall include the following control and monitoring arrangements, when applicable:

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— Remote indication and alarm if a brake is not released when power applied to the motors. The brake alarmshall be given by an independent mechanical sensor.

— Remote indication and alarm for overheating of an electric motor.— A permanent remote indication of loads during jacking and retrieval shall be provided. For a lattice leg

unit the load per chord is as a minimum to be presented. Alarm signal to be given when maximum load isexceeded.

— For hydraulic jacking system, records of oil samples shall be examined.Guidance note:

The frequency of oil samples should follow OEM recommendations but typically twice per year for self-elevating self-propelledunits with a high jacking frequency.


— Audible and visible alarm to indicate out-of-level.— Audible and visible alarm to indicate rack phase differential.— Indication of inclination.— Indication of power consumption.— Indication of hydraulic/pneumatic pressure.— Indication of position of pin and yoke.

(this includes requirements in MODU code 4.14.3).

6.7 Testing and inspection

6.7.1 GeneralThe testing of the jacking gear system shall in general consist of workshop testing, inspection afterinstallation and testing on board.

6.7.2 Workshop testingSpin test and contact pattern test shall be carried out according to the DNV rules for ships Pt.4 Ch.4. Sec.2D.

6.7.3 Installation inspectionThe alignment between the pinions and rack shall be checked both longitudinally and with regard to distancebetween pinion centre and rack.The gearing box shall be inspected on the following (with reference to DNV rules for ships Pt.4 Ch.4 H):

— shaft alignment, see DNV rules for ships Pt.4 Ch.4 Sec.1 H300— fastening of propulsion gearboxes (stoppers and bolt tightening)— flushing, applicable if the system is opened during installation. Preferably with the foreseen gear oil. If

flushing oil is used, residual flushing oil shall be avoided— lubrication oil shall be as specified (viscosity and FZG class) on maker’s list— pressure tests to nominal pressure (for leakage) where cooler, filters or piping is mounted onboard— tooth contact pattern.

6.7.4 Testing on boardThe testing on board is part of the jacking trials as described in Ch.7 Sec.4 [6].

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SECTION 2 ELECTRICAL INSTALLATIONS

1 General

1.1 IntroductionThis section provides principles, technical requirements and guidance for design, manufacturing andinstallation of electrical installations.Table 1 lists references required for a complete understanding of this chapter.


Reference Title


IEC 61892 Mobile and fixed offshore units – Electrical installations

1.2 ApplicationThe requirements in this section apply to:

— all electrical installations with respect to safety for personnel and fire hazard— all electrical installations serving essential or important services with respect to availability.

1.3 Plans and data to be submittedDocumentation related to electrical installation system design shall be submitted as required by Table 2.



E010 − Overall single linediagram For AC, DC and UPS systems AP

E050 − Single line diagrams/consumer list for switchboards For AC, DC and UPS systems AP

E040 − Electrical powerconsumption balance For AC, DC and UPS systems AP

E220 − Electrical systemphilosophy

System philosophy may not be required if the “overall singleline diagram” is sufficient to give necessary understanding ofthe operation and relevant operation modes of the system.

FI

E200 − Short circuitcalculations FI

E210 − Harmonic distortioncalculations

Required when more than 20% of connected load is by semi-conductor assemblies, in relation to connected generatingcapacity.

FI

Electric powersystems

E100 − Voltage dropcalculations

Upon request and when a motor rated above 30% of thefeeding generator(s) or transformer(s) rated power is starteddirect on line.

FI, R

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E080 − Discrimination analysis

The document shall cover:generator protection

main switchboard circuits (see DNVGL-OS-D201 Ch.1 Sec.1[4.9.1])

emergency switchboard circuits (see DNVGL-OS-D201 Ch.1Sec.1 [4.9.2])

battery and UPS systems

AP

Z030 − Arrangement plan

Including locations of power sources, switchboards anddistribution boards for main and emergency power, UPSs andbatteries. Arrangement of access doors, fire divisions and highfire risk areas related to the above.

FI

Z071 − Failure mode and effectanalysis (FMEA)

Required if separate emergency source of power is omitted inaccordance with DNVGL-OS-D201 Ch.2 Sec.2 [3.1.4].Upon request for other systems.

AP

Z140 − Test procedure forquay and sea trial

Redundancy and failure modes based on FMEA. Required ifseparate emergency source of power is omitted in accordancewith DNVGL-OS-D201 Sec.2 [3.1.4].

Upon request for other systems.

AP

Motor starters E170 − Electrical schematicdrawing Starters for essential services. AP

Cables E030 − Cable selectionphilosophy AP

Emergencystop system

E170 − Electrical schematicdrawing

Emergency stop of electrical propulsion motors, pumps andfans, showing fail to safe functionality. AP

Installationin hazardousareas

E090 − Table of Ex-installation Based on approved area classification drawing and ESDphilosophy (if relevant). AP

E190 − Lighting description APLightingsystems Z030 − Arrangement plan Emergency lighting arrangement. AP

For general requirements to documentation, including definition of the codes and documentation types, seeDNVGL-RU-SHIP Pt.1 Ch.3.For documentation requirements of electrical equipment required to be delivered with DNV GL productcertificate see DNVGL-OS-D202.

2 PrinciplesThe following principles apply to electrical installations:

— Electrical installations shall be such that the safety of passengers, crew and unit from electrical hazards, isensured.

— There shall be two mutually independent and self contained electric power supply systems on board:— main electric power supply system— emergency electric power supply system. Exceptions are given in DNVGL-OS-D201 Ch.2 Sec.2 [3.1.4].

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— Services required for normal operation of the offshore unit shall be operable with the emergency electricalpower generation and distribution system being unavailable, unless such services are permitted to bepowered by emergency electrical power supply only.

— All consumers that support functions required to be available in normal operation, shall be supplied fromdistribution systems independent of the emergency electrical power supply system. Exemptions are madefor one of redundant consumers required for dead ship recovery.

— All consumers required to be available in emergency operation shall be supplied from distribution systemsindependent of the main electric power supply system.

— Consumers required having both main and emergency supply shall be supplied as required by relevantrules applicable for these consumers. The primary supply shall be from the main system.

— Offshore units without a dedicated emergency electric power supply system are accepted upon compliancewith requirements in DNVGL-OS-D201 Ch.2 Sec.2 [3.1.4].

Relevant specifications for system voltage, frequency and earthing are given in DNVGL-OS-D201 Ch.2 Sec.2as follows:

Table 3


System earthing DNVGL-OS-D201 Ch.2 Sec.2 [1.1.3]

Types of distribution system DNVGL-OS-D201 Ch.2 Sec.2 [1.1.4]

Hull return systems DNVGL-OS-D201 Ch.2 Sec.2 [1.1.5]

System voltages and frequencies DNVGL-OS-D201 Ch.2 Sec.2 [1.2]

Lightning protection DNVGL-OS-D201 Ch.2 Sec.2 [9.6]

Earthing of aluminium superstructures on steel offshore units DNVGL-OS-D201 Ch.2 Sec.2 [9.7]

3 Arrangements and installation

3.1 ArrangementArrangements for electrical installations are specified in DNVGL-OS-D202 Ch.2 Sec.2 [9] as follows:

Table 4


Ventilation DNVGL-OS-D201 Ch.2 Sec.2 [9.1.1]

Arrangement of power generation and distribution DNVGL-OS-D201 Ch.2 Sec.2 [9.1.2]

Installation of switchboards1 DNVGL-OS-D201 Ch.2 Sec.2 [9.2.1]

Arrangement for high voltage switchboard rooms DNVGL-OS-D201 Ch.2 Sec.2 [9.2.2]

Passage ways for main and emergency switchboards DNVGL-OS-D201 Ch.2 Sec.2 [9.2.3]

Distribution switchboards DNVGL-OS-D201 Ch.2 Sec.2 [9.2.4]

1) Applies for transformers as well

For the arrangement of batteries see Sec.4 [4.3].

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3.2 InstallationThe following applies for installation of electrical equipment:

— All electrical equipment shall be permanently installed and “electrically safe”. This shall prevent injury topersonnel, when the equipment is handled or touched in the normal manner. (Interpretation of SOLASCh.II-1/45.1.3)

— All electrical equipment shall be selected and installed so as to avoid EMC problems. Thus preventingdisturbing emissions from equipment, or preventing equipment from becoming disturbed and affecting itsintended function(s).

— Electrical equipment shall be placed in accessible locations so that those parts, which require manualoperation, are easily accessible.

— Heat dissipating electrical equipment as for example lighting fittings and heating elements, shall belocated and installed so that high temperature equipment parts do not damage associated cables andwiring, or affect surrounding material or equipment, and thus become a fire hazard. (Interpretation ofSOLAS Ch.II- 1/45.7)

— Equipment shall be installed in such a manner that the circulation of air to and from the associatedequipment or enclosures is not obstructed. The temperature of the cooling inlet air shall not exceed theambient temperature for which the equipment is specified.

— All equipment of smaller type (luminaries, socket outlets etc.) shall be protected against mechanicaldamage either by safe location or by additional protection, if not of a rugged metallic construction.

In addition installation requirements are given in DNVGL-OS-D201 Ch.2 Sec.10 [2] as listed in Table 5.

Table 5



High voltage switchgear DNVGL-OS-D201 Ch.2 Sec.10 [2.1.3]

Passage of switchboards DNVGL-OS-D201 Ch.2 Sec.10 [2.1.4]

Transformers DNVGL-OS-D201 Ch.2 Sec.10 [2.1.5]

Heating and cooking appliances DNVGL-OS-D201 Ch.2 Sec.10 [2.1.6]

Equipment enclosure, ingress protection DNVGL-OS-D201 Ch.2 Sec.10 [2.2]

4 Power supply

4.1 Main

4.1.1 CapacityThe main power supply system shall have the capacity to supply power to all services necessary formaintaining the offshore unit in normal operation without recourse to the emergency source of power.There shall be component redundancy for main sources of power, transformers and power converters in themain power supply system so that with any source, transformer or power converter out of operation, thepower supply system shall be capable of supplying power to the following services:

— those services necessary to provide normal operational conditions and safety— starting the largest essential or important electric motor on board, except auxiliary thrusters, without the

transient voltage and frequency variations exceeding the limits specified in DNVGL-OS-D201 Ch.2 Sec.2[1.2]

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— ensuring minimum comfortable conditions of habitability which shall include at least adequate services forcooking, heating, domestic refrigeration (except refrigerators for air conditioning), mechanical ventilation,sanitary and fresh water

— for a duplicated essential or important auxiliary, one being supplied non-electrically and the otherelectrically (e.g. lubricating oil pump No. 1 driven by the main engine, No. 2 by electric motor), it is notexpected that the electrically driven auxiliary is used when one generator is out of service

For “dead ship” recovery, see Sec.1 [5.4].

4.1.2 Generator prime moversEach generator shall normally be driven by a separate auxiliary engine not to be used for driven otherauxiliary systems.Auxiliary engines shall comply with the requirements in DNVGL-OS-D101 Sec.5 [2].

Guidance note:

Generators based on variable speed drives will be evaluated in each case. As a minimum, the following should be evaluated:

— availability

— stability of output voltage and frequency

— short circuit capability and protection.


4.1.3 System functionalityAt least two generator sets, connected to separate main busbar sections, shall be arranged with systems forstarting in a blackout situation. However, only one standby generator may be permitted if this generator isnot intended to be used for normal operation of the offshore unit.Requirements to energy for starting and supply to auxiliaries required for starting are given in DNVGL-OS-D201 Ch.2 Sec.2 [2.2.2].

4.1.4 Load shedding and automatic restoration of powerThe system shall be so arranged that the electrical supply to ensure safety of the offshore unit, will bemaintained or immediately restored in case of loss of any one of the generators in service. This means:

— All generators shall be equipped with automatic load shedding or other automatic means to preventsustained overload of any generator, see DNVGL-OS-D201 Ch.2 Sec.2 [7.1.1].

— Where the electrical power is normally supplied by one generator provision shall be made, upon loss ofpower, for automatic starting and connecting to the main switchboard of standby generator(s) of sufficientcapacity with automatic restarting of the essential auxiliaries, in sequential operation if required. Startingand connection to the main switchboard of the standby generator shall be preferably within 30 seconds,but in any case not more than 45 seconds, after loss of power.

— Where prime movers with longer starting time are used, this starting and connection time may beexceeded upon approval from the society.

— Where more than one generating set is necessary to cover normal loads, the power supply system shallbe provided with suitable means for tripping or load reduction of consumers. If necessary, importantconsumers may be tripped in order to permit propulsion and steering and to ensure safety. If theremaining on line generators are not able to permit propulsion and steering and to ensure safety,provision shall be made for automatic starting and connection to the main switchboard of the standbygenerator.

4.2 Emergency power supply systemsRequirements for emergency power supply systems are given in DNVGL-OS-D201 Ch.2 Sec.2 [3].

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Table 6


Emergency power source DNVGL-OS-D201 Ch.2 Sec.2 [3.1.1]

Capacity DNVGL-OS-D201 Ch.2 Sec.2 [3.1.2]

Services to be supplied DNVGL-OS-D201 Ch.2 Sec.2 [3.1.3]

Independent installation of power sources DNVGL-OS-D201 Ch.2 Sec.2 [3.1.4]

Emergency switchboard DNVGL-OS-D201 Ch.2 Sec.2 [3.1.5]

Transitional source DNVGL-OS-D201 Ch.2 Sec.2 [3.2]

Emergency generators DNVGL-OS-D201 Ch.2 Sec.2 [3.3]

4.3 Battery systemsTrip of battery by emergency shutdown system (ESD) shall be arranged as required by DNVGL-OS-A101 Ch.2Sec.4.Additional requirements for rechargeable Lead Acid and NiCd batteries are given in DNVGL-OS-D201 Ch.2Sec.2 as follows:

Table 7


Capacity of accumulator batteries DNVGL-OS-D201 Ch.2 Sec.2 [4.1.1]

Battery powered systems DNVGL-OS-D201 Ch.2 Sec.2 [4.1.2]

Battery monitoring DNVGL-OS-D201 Ch.2 Sec.2 [4.1.3]

Arrangement DNVGL-OS-D201 Ch.2 Sec.2 [4.1.3]


Charging stations for battery powered fork lift (if applicable) DNVGL-OS-D201 Ch.2 Sec.2 [4.1.5]

Materials for installation DNVGL-OS-D201 Ch.2 Sec.10 [2.3.2]

Testing DNVGL-OS-D201 Ch.2 Sec.10 [2.3.3]

Requirements for installation of electrical equipment in battery rooms, lockers and boxes are given in Sec.3[3.2], alternatively DNVGL-OS-D201 Ch.2 Sec.11 [3.2.5].Installation of rechargeable battery types other than Lead Acid and NiCd will be evaluated case-by-casebased on the above requirements and DNV rules for ships Pt.6 Ch.28 Tentative rules for Battery Power.Installation and ventilation recommendations from the manufacturer should always be followed.

4.4 Power supply to jacking gearFor power supply to jacking gear, see Sec.1 [6].

5 Electrical power distributionRequirements to electric power distribution are given in DNVGL-OS-D201 Ch.2 Sec.2 [6] as follows:

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Table 8


General DNVGL-OS-D201 Ch.2 Sec.2 [6.1.1]

Consequence of single failure DNVGL-OS-D201 Ch.2 Sec.2 [6.1.2]

Division of main busbars See below

Generator circuits DNVGL-OS-D201 Ch.2 Sec.2 [6.1.4]

Lighting DNVGL-OS-D201 Ch.2 Sec.2 [6.2]

Power supply to control and monitoring systems DNVGL-OS-D201 Ch.2 Sec.2 [6.3]

Low voltage shore connections DNVGL-OS-D201 Ch.2 Sec.2 [6.4]

Due to redundancy requirement for jacking machinery, the main busbar shall be subdivided into at least twoparts. So far as is practicable, the connection of generating sets and other duplicated equipment shall beequally divided between the parts. In addition:

— For high voltage distribution systems, the main busbar sections shall be connected by circuit breaker.— For low voltage distribution systems, busbars which can be divided into at least two parts within three

hours can be accepted. (System category “repairable system” R3 as defined in DNVGL-OS-D202 Ch.2Sec.1 [2.1.2]).

6 ProtectionRequirements to protection are given in DNVGL-OS-D201 Ch.2 Sec.2 [7] as follows:

Table 9


System protection DNVGL-OS-D201 Ch.2 Sec.2 [7.1]

Circuit protection DNVGL-OS-D201 Ch.2 Sec.2 [7.2]

Generator protection DNVGL-OS-D201 Ch.2 Sec.2 [7.3]

Transformer protection DNVGL-OS-D201 Ch.2 Sec.2 [7.4]

Motor protection DNVGL-OS-D201 Ch.2 Sec.2 [7.5]

Battery protection DNVGL-OS-D201 Ch.2 Sec.2 [7.6]

Harmonic Filter protection DNVGL-OS-D201 Ch.2 Sec.2 [7.7]

7 ControlRequirements to control of electric equipment are given in DNVGL-OS-D201 Ch.2 Sec.2 [8] as follows:

Table 10


Control circuits DNVGL-OS-D201 Ch.2 Sec.2 [8.1]

Control of generator sets and main power supply DNVGL-OS-D201 Ch.2 Sec.2 [8.2]

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Main and emergency switchboard control DNVGL-OS-D201 Ch.2 Sec.2 [8.3]

Motor control DNVGL-OS-D201 Ch.2 Sec.2 [8.4]

Emergency stop DNVGL-OS-D201 Ch.2 Sec.2 [8.5]

8 Electrical equipment:In general, DNV GL’s electrical equipment requirements are based on IEC standard IEC 61892, part 1,“General requirements and conditions”, part 2 “Systems design”, and part 3 “Equipment”.For environmental requirements, see Ch.2 Sec.3 [3].Other general requirements for electrical equipment are given in DNVGL-OS-D201 Ch.2 Sec.3 as listed inTable 11.

Table 11


Electrical parameters DNVGL-OS-D201 Ch.2 Sec.3 [3.1]

Maximum operating temperatures DNVGL-OS-D201 Ch.2 Sec.3 [3.2]

Mechanical strength DNVGL-OS-D201 Ch.2 Sec.3 [4.1]

Cooling and anti-condensation DNVGL-OS-D201 Ch.2 Sec.3 [4.2]

Termination and cable entrances DNVGL-OS-D201 Ch.2 Sec.3 [4.3]

Equipment protective earthing DNVGL-OS-D201 Ch.2 Sec.3 [4.4]

Enclosures ingress protection DNVGL-OS-D201 Ch.2 Sec.3 [4.5]

Clearance and creepage distances DNVGL-OS-D201 Ch.2 Sec.3 [4.6]

Insulation materials DNVGL-OS-D201 Ch.2 Sec.3 [6.1]

Requirements for specific electrical equipment are given in DNVGL-OS-D201 Ch.2 as listed in Table 12.

Table 12


Switchgear and control gear assemblies DNVGL-OS-D201 Ch.2 Sec.4

Rotating machines DNVGL-OS-D201 Ch.2 Sec.5

Power transformers DNVGL-OS-D201 Ch.2 Sec.6

Semi-conductor converters DNVGL-OS-D201 Ch.2 Sec.7

Miscellaneous equipment DNVGL-OS-D201 Ch.2 Sec.8

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9 Cables

9.1 Cable selectionThese technical requirements for cables and cable installations are considered relevant for the system designphase of a project. However, they apply as well to the final installation on the offshore unit. Details can befound in DNVGL-OS-D201 Ch.2 Sec.2 [10] as detailed in Table 13.

Table 13


Fire resistant cables DNVGL-OS-D201 Ch.2 Sec.2 [10.1.2]

Voltage rating DNVGL-OS-D201 Ch.2 Sec.2 [10.1.3]

Colour code on earthing cable DNVGL-OS-D201 Ch.2 Sec.2 [10.1.4]

Cable separation and protection DNVGL-OS-D201 Ch.2 Sec.2 [10.1.5]

Cable temperature DNVGL-OS-D201 Ch.2 Sec.2 [10.2]

Choice of insulation materials DNVGL-OS-D201 Ch.2 Sec.2 [10.3]

Rating of earth conductors DNVGL-OS-D201 Ch.2 Sec.2 [10.4]

Correction factors DNVGL-OS-D201 Ch.2 Sec.2 [10.5]

Parallel connection of cables DNVGL-OS-D201 Ch.2 Sec.2 [10.6]

Additional requirements for AC installations and special DCinstallations DNVGL-OS-D201 Ch.2 Sec.2 [10.7]

Rating of cables DNVGL-OS-D201 Ch.2 Sec.2 [10.8]

9.2 Cable construction and ratingThe cables shall comply to the standards as described in DNVGL-OS-D201 Ch.2 Sec.9 as listed in Table 14.

Table 14


Application DNVGL-OS-D201 Ch.2 Sec.9 [1]

General cable construction DNVGL-OS-D201 Ch.2 Sec.9 [2]

High voltage cables DNVGL-OS-D201 Ch.2 Sec.9 [3]

Low voltage power cables DNVGL-OS-D201 Ch.2 Sec.9 [4]

Control and instrumentation cables DNVGL-OS-D201 Ch.2 Sec.9 [5]

Data communication cables DNVGL-OS-D201 Ch.2 Sec.9 [6]

Fibre optic cables DNVGL-OS-D201 Ch.2 Sec.9 [7]

Inspection and testing DNVGL-OS-D201 Ch.2 Sec.9 [8]

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9.3 Cable routing and installationsCable runs shall be installed well clear of substantial heat sources such as boilers, heated oil tanks, steam,exhaust or other heated pipes, unless it is ensured that the insulation type and current rating is adapted tothe actual temperatures at such spaces. Other relevant requirements are given in DNVGL-OS-D201 Ch.2Sec.2 and DNVGL-OS-D201 Ch.10 as detailed in Table 15.

Table 15


Separation of cables for emergency services, essential andimportant equipment DNVGL-OS-D201 Ch.2 Sec.2 [9.5.2]

Separation of main generators or main power converters cabling DNVGL-OS-D201 Ch.2 Sec.2 [9.5.2]

Routing of cables DNVGL-OS-D201 Ch.2 Sec.10 [3.2]

Penetrations of bulkheads and decks DNVGL-OS-D201 Ch.2 Sec.10 [3.3]

Fire protection measures DNVGL-OS-D201 Ch.2 Sec.10 [3.4]

Support and fixing of cables and cable runs DNVGL-OS-D201 Ch.2 Sec.10 [3.5]

Cable expansion DNVGL-OS-D201 Ch.2 Sec.10 [3.6]

Cable pipes DNVGL-OS-D201 Ch.2 Sec.10 [3.7]

Splicing of cables DNVGL-OS-D201 Ch.2 Sec.10 [3.8]

Termination of cables DNVGL-OS-D201 Ch.2 Sec.10 [3.9]

Trace or surface heating installation requirements DNVGL-OS-D201 Ch.2 Sec.10 [3.10]

Additional requirements for cables installed in hazardous areas are given in DNVGL-OS-D201 Ch.2 Sec.11 asdetailed in Table 16.

Table 16


Cable types DNVGL-OS-D201 Ch.2 Sec.11 [4.2.1]

Fixed cable installations DNVGL-OS-D201 Ch.2 Sec.11 [4.2.2]

Flexible cables DNVGL-OS-D201 Ch.2 Sec.11 [4.2.3]

Penetrations of bulkheads and decks DNVGL-OS-D201 Ch.2 Sec.11 [4.2.4]

Cable entrance into equipment DNVGL-OS-D201 Ch.2 Sec.11 [4.2.5]

Termination and wiring inside Ex-e and Ex-d enclosures DNVGL-OS-D201 Ch.2 Sec.11 [4.2.6]

Intrinsically safe circuit wiring and termination DNVGL-OS-D201 Ch.2 Sec.11 [4.2.7]

Special conditions in EX certificates DNVGL-OS-D201 Ch.2 Sec.11 [4.2.8]

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SECTION 3 AREA ARRANGEMENTS

1 General

1.1 ScopeThis chapter covers the arrangement of areas in general and hazardous areas with the relevant requirementsfor machinery and electrical equipment.Table 1 lists references required for a complete understanding of this chapter.


Reference Title





DNVGL-OS-D202 Automation, safety and telecommunication systems

IEC 61892 Mobile and fixed offshore units – Electrical installations

1.2 Plans and data to be submittedDocumentation related to this chapter shall be submitted as required by Table 2.



G070 – Source of release schedule FIHazardous area classification

G080 – Hazardous area classification drawing AP

Ventilation systems S012 – Ducting diagram AP

Muster station/ safe area Z030 – Arrangement plan AP

Escape route G120 – Escape route drawing AP


2 Divisions and equipment location

2.1 GeneralThe unit or installation shall be divided into different areas according to the type of activities that will becarried out and the associated hazard potential.Areas of high risk potential shall be segregated from areas of low risk potential, and from areas containingimportant safety functions. Incident escalation between areas shall be avoided.

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Accommodation and other areas important for safety, such as control stations, shall be located in areasclassified as non-hazardous by location, and as far as practicable away from hazardous areas for hydrocarbonprocessing, hydrocarbon storage, wellheads, risers and drilling. The effect of prevailing winds and potentialfor segregation by less hazardous areas shall also be considered for area protection.Use of firewalls, blast walls, cofferdams etc. shall be considered in cases where segregation by physicaldistance is not sufficient.Where control stations or control functions are located in LER/LIRs outside the accommodation block/safearea special precautions against gas ignition related to gas detection, ventilation and shutdown will need tobe provided.Specific requirements for location of equipment are given in DNVGL-OS-A101 Ch.2 as listed in Table 3.

Table 3 Overview on location of equipment requirements

Description Reference in DNVGL-OS-A101

Location of safety systems DNVGL-OS-A101 Ch.2 Sec.2 [4.1]

Location of air intakes and other openings DNVGL-OS-A101 Ch.2 Sec.2 [4.2]

Fired heaters, combustion engines and hot surfaces DNVGL-OS-A101 Ch.2 Sec.2 [4.3]

Location of flares and vents DNVGL-OS-A101 Ch.2 Sec.2 [4.4]

Storage of dangerous goods DNVGL-OS-A101 Ch.2 Sec.2 [5]

Cranes and lay down areas DNVGL-OS-A101 Ch.2 Sec.2 [6]

Asbestos and railing and barriers DNVGL-OS-A101 Ch.2 Sec.2 [7]

Mooring, moonpool, production and well testing and control station DNVGL-OS-A101 Ch.2 Sec.6 [2]

2.2 Electrical installationsArrangements for electrical installations are specified in DNVGL-OS-D201 Ch.2 Sec.2 [9] as listed in Table 4.

Table 4 Overview on requirements for arrangements for electrical systems



Arrangement of power generation and distribution DNVGL-OS-D201 Ch.2 Sec.2 [9.1.2]

Installation of switchboards DNVGL-OS-D201 Ch.2 Sec.2 [9.2.1]

Arrangement for high voltage switchboard rooms DNVGL-OS-D201 Ch.2 Sec.2 [9.2.2]

Passage ways for main and emergency switchboards DNVGL-OS-D201 Ch.2 Sec.2 [9.2.3]

Distribution switchboards DNVGL-OS-D201 Ch.2 Sec.2 [9.2.4]

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3 Hazardous areas

3.1 Area classificationHazardous areas are classified as follows:

— Zone 0: in which an explosive gas atmosphere is continuously present or present for long periods. (Typicalfor continuous grade source present for more than 1000 hours a year or that occurs frequently for shortperiods).

— Zone 1: in which an explosive gas atmosphere is likely to occur in normal operation. (Typical for primarygrade source present between 10 and 1000 hours a year).

— Zone 2: in which an explosive gas atmosphere is not likely to occur in normal operation, and if it doesoccur, is likely to do so infrequently and will exist for a short period only. (Typical for secondary gradesource present for less than 10 hours per year and for short periods only).

3.2 Battery rooms, paint stores, and welding gas bottle storesElectrical equipment installed in battery rooms lockers or boxes, paint stores or welding gas bottle stores,and in ventilation ducts serving such spaces shall be suitable for installation in zone 1 with the followingrequirements for gas group and ignition temperature:

— battery rooms: minimum gas group II C and temperature class T1— paint stores: minimum gas group II B and temperature class T3— welding gas bottle stores: minimum gas group II C and temperature class T2.

Cables routed through such spaces shall either be suitable for installation in hazardous area zone 1, or beinstalled in metallic conduit.Areas on open deck within 1m of inlet and exhaust ventilation openings or within 3 m of exhaust outlets withmechanical ventilation are classified as zone 2.Enclosed spaces giving access to such areas may be considered as non-hazardous, provided that:

— the door to the space is a gastight door with self-closing devices and without holding back arrangements(a watertight door is considered gastight)

— the space is provided with an acceptable, independent, natural ventilation system ventilated from a safearea

— warning notices are fitted adjacent to the entrance to the space stating that the store contains flammableliquids or gas.

Battery rooms and lockers or boxes shall be regarded as zone 2 hazardous areas with respect to accessdoors, lids or removable panels and possible interference with other rooms.The fan mounted inside extract ventilation ducts shall be of non-sparking type.

3.3 Requirements for specific systems

3.3.1 Combustion enginesCombustion equipment and combustion engines shall normally not be located in hazardous areas. Whereit is necessary to house combustion engines in a hazardous area, either the equipment shall be placed in apressurized space or the equipment shall be otherwise protected to prevent ignition (see DNVGL-OS-A101Ch.2 Sec.2 [4.3].

3.3.2 Electrical installations and cablesElectrical equipment and cables installed in hazardous areas shall be limited to that necessary for operationalpurposes. Electrical equipment with temperature class T3 (maximum 200°C) shall be used when hydrocarbongases give rise to hazardous areas. The installation in hazardous areas shall comply with DNVGL-OS-D201Ch.2 Sec.11.

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Electrical cables are as far as possible to be routed outside areas containing drilling mud (see DNVGL-OS-A101 Ch.2 Sec.6 [3.3].Electrical equipment left operational after APS shutdown or as located in non-hazardous areas affected by agas release shall be certified for operation in zone 2 areas. The certification requirement does not apply if theroom where the equipment is located is efficiently isolated (typically living quarters).

4 Ventilation systemsThe ventilation system shall be designed to maintain acceptable working and living environment for thepersonnel and non-detrimental conditions for equipment and machinery. There shall be independentventilation systems for hazardous and non-hazardous areas. Non-hazardous enclosed spaces shall beventilated with over pressure in relation to hazardous areas.Regarding ventilation of spaces in which machinery is operated and where flammable or toxic gases orvapours may accumulate, where low oxygen atmosphere may occur, machinery spaces and emergencygenerator room shall be provided with adequate ventilation under all conditions.

Guidance note:

By adequate ventilation is meant natural or mechanical ventilation sufficient to prevent an accumulation of gases above aconcentration of 25% of their lower explosion limit (LEL).


Specific requirements for specific areas are given in DNVGL-OS-A101 and DNVGL-OS-D101 as listed in Table5.

Table 5 Overview on ventilation requirements

Description Reference in DNVGL-OS-A101 and DNVGL-OS-D101

Location for air intakes and other openings DNVGL-OS-A101 Ch.2 Sec.3 [4.3]

Accommodation and control spaces DNVGL-OS-D101 Ch.2 Sec.4 [11.1]

Ventilation of Machinery spaces DNVGL-OS-D101 Ch.2 Sec.4 [11.2]

Ventilation of Gas Hazardous areas DNVGL-OS-D101 Ch.2 Sec.4 [11.3]

Fans serving hazardous spaces DNVGL-OS-D101 Ch.2 Sec.4 [11.4]

Ductwork DNVGL-OS-D101 Ch.2 Sec.4 [11.5]

5 Marking and signboardsFor the installation of marking and signboards, the overview of Table 6 can be followed.

Table 6 Marking and signboards – overview

Text of signboard (example) Places to be displayed OS rule reference

HAZARDOUS AREA On self-closing doors between areas with differentarea classification.

DNVGL-OS-A101 Ch.2 Sec.5[5.2.3]

“ESCAPE TO SEA” Escape ways to sea. DNVGL-OS-A101 Ch.2 Sec.5[5.1.1]

“SMOKING AND USE OF NAKEDLIGHTS PROHIBITED”

Areas for storage of flammable, radioactive,explosive or otherwise hazardous substances.

DNVGL-OS-A101 Ch.2 Sec.2[5.1]

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“TO BE KEPT CLOSED AT SEA”

Internal openings which are kept permanentlyclosed during the operation of the unit.Locally operated doors or hatch covers.

Hatch on upper deck to engine room.

Rope hatches on mooring deck, forward and aft.

Hatch on aft mooring deck to steering gear room.

Hatch on forward mooring deck to bosun store.

Hatches on main deck to fuel oil and ballast tanks.

DNVGL-OS-C301 Ch.2 Sec.2[3.2.2]

DNVGL-OS-C301 Ch.2 Sec.2Table 4

“SEA DIRECT” All connections (inlet/outlet) to sea.

DNVGL-OS-D101 Ch.2 Sec.1[1.2]

DNVGL-OS-C301 Ch.2. Sec.2[6.1.1]

"SOUNDING PIPE of(compartment)"

On sounding pipes for tanks, cofferdams and pipetunnels.


“MAXIMUM ALLOWABLE PUMPCAPACITY FOR TANKS WHICHCAN BE FILLED BY PUMPS NOTINSTALLED IN THE VESSEL IS(specify capacity) M3/H”

On loading station pipe connection for filling oftanks which can be filled by pumps not installed inthe vessel.

DNVGL-OS-D101 Ch.2 Sec.3[5.2.1]

“CAUTION! NO BURNER TO BEFIRED BEFORE THE FURNACE HASBEEN PROPERLY PURGED”

Boiler control panels next to boiler and remoteboiler panels.Control panel for incinerator.

Control panel for inert gas generator.



Tank and space numberAll air pipes from tanks and spaces shall be clearlymarked at the upper end with the tank or spacenumber.


Indication open/ close

If wrong operation may cause damage onswitchgear for sectioning on the busbar theninstructions for correct operation shall be given bysignboard on the switchboard. It shall be clearlyindicated whether such switchgear is open orclosed.


“HIGH VOLTAGE”High voltage machines, transformers, cables,switchgear and control gear assemblies (markedevery 20 meters).



“CAUTION! (rated voltage) FUSESONLY”

Switchgear fed from more than one individuallyprotected circuit.


“DANGER! (maximum voltage)VAC ONLY FOR CONNECTION OF(type of equipment)”

Each socket outlets for portable appliances whichare not handheld during operation (i.e. weldingtransformers, refrigerated containers).


“WARNING! EXPLOSIVE GAS NOSMOKING OR USE OF NAKEDLIGHTS”

Battery rooms and on doors or covers of boxes orlockers.


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“WARNING! (rated voltage)VOLTAGE” Battery systems above 50V. DNVGL-OS-D201 Ch.2 Sec.10

[2.5.2]

“ONLY TO BE USED IN PORT”

Motors on open deck shall have ingress protectionIP 56, and either:be naturally cooled, i.e. without external cooling fan

be vertically mounted and equipped with anadditional steel hat preventing ingress of water orsnow into any external ventilator

or be equipped with a signboard requiring that themotor shall only be used in port, and be providedwith additional covers (e.g. tarpaulins) at sea.

DNVGL-OS-D201 Ch.2 Sec.10Table 10-1

Guidance/ conditions for safe use

Signboards giving guidance for safe use, orconditions for use, shall be fitted, if necessary, inorder to avoid inadvertent or dangerous operation ofequipment and or systems.


“ENGINE ALARM”“INERGEN”

“H2S”

“HC”

On all visual alarms in rooms / spaces shall bemarked with name of alarm.


Instructions for correct operation

Switchboards that are arranged for supply by two(or more) alternative circuits shall be provided withinterlock or instructions for correct operation bysignboard on the switchboard. Positive indication ofwhich of the circuits is feeding the switchboard shallbe provided.


“ALARM TO BE SOUNDED PRIORTO REMOTE OPERATION”

On location(s) where remote operation of thewindlasses or winches can be carried out.

DNVGL-OS-E301 Ch.2 Sec.4[11.5.14]

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SECTION 4 CONTROL AND COMMUNICATION SYSTEMS ANDEMERGENCY SHUTDOWN

1 General

1.1 IntroductionThis chapter list requirements for control and telecommunication systems and emergency shutdown.Table 1 lists references required for a complete understanding of this chapter.


Reference Title

IMO Res. A.830(19) Code on Alarms and Indicators, 1995



1.2 ApplicationThe requirements in this system are in special applicable for the fire and gas system, platform automationand GA/PA system. In this respect, the suppliers of these systems should take special notice of these duringtheir system design, delivery and installation on board.

1.3 Plans and data to be submittedA general overview of the required plans and analyses to be submitted is listed Table 2. A more detailedoverview, tuned to the specific design and project scope can be obtained from DNV GL’s Nauticus ProductionSystem.


Object Documentation type Additionaldescription Info

Vessel control and monitoring systems Z140 – Test procedure for quay and sea trial AP

Engineer's alarm system I200 – Control and monitoring systemdocumentation AP

Integrated control and monitoring system G170 – Control system philosophy AP

Emergency shut down system G130 – Control and monitoring systemdocumentation AP


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2 Principles

2.1 GeneralThe principles for automation, safety and telecommunication systems are described in DNVGL-OS-D202 asfurther outlined in the remaining of this chapter.The definitions of safety and important systems together with the different levels of system availability asgiven in Ch.3 Sec.2 [2] are applicable for the automation system controlling these systems as well.

2.2 Response to failures

2.2.1 Failure detectionEssential and important systems shall have facilities to detect the most probable failures that may causereduced or erroneous system performance.Failures detected shall initiate alarms in an assigned manned control station.The failure detection facilities shall at least, but not limited to, cover the following failure types:

— power failures.

Additionally for computer based systems:

— communication errors— hardware failures— software execution failures.

Additional for essential/safety systems:

— loop failures— earth faults.

2.2.2 Fail-safe functionalityThe most probable failures, for example loss of power or wire failure, shall result in the least critical of anypossible new conditions.

3 System designThe safety and automation system shall be designed as mutually independent systems. The differentelements shall not be designed as one combined system, where safety functions are combined withautomation functions.For essential and important systems, deviations between a command action and expected result of thecommand action shall initiate an alarm.Planning and reporting system elements shall have no outputs for real-time process equipment control duringplanning mode.Output from calculation, simulation or decision support modules shall not suppress basic informationnecessary to allow safe operation of essential and important functions.Other detailed requirements are given in DNVGL-OS-D202 Ch.2 Sec.2 as listed in Table 3.

Table 3


Automation system DNVGL-OS-D202 Ch.2 Sec.2 [1.2]

Safety system DNVGL-OS-D202 Ch.2 Sec.2 [1.4]

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Alarms DNVGL-OS-D202 Ch.2 Sec.2 [1.6]

Indications DNVGL-OS-D202 Ch.2 Sec.2 [1.7]

System operation and maintenance DNVGL-OS-D202 Ch.2 Sec.2 [2.1]

For computer based systems, additional requirements as given in DNVGL-OS-D202 Ch.2 Sec.3 apply asdetailed in Table 4.

Table 4

Description References in DNVGL-OS-D202

General requirements DNVGL-OS-D202 Ch.2 Sec.3 [1]

System software DNVGL-OS-D202 Ch.2 Sec.3 [2]

Network systems and communication DNVGL-OS-D202 Ch.2 Sec.3 [3]

4 Component design and installationFor the design of components and installed typically under responsibility from the yard, the specificrequirements in DNVGL-OS-D202 Ch.2 Sec.4 apply as detailed in Table 5.

Table 5


General DNVGL-OS-D202 Ch.2 Sec.4 [1]

Environmental conditions DNVGL-OS-D202 Ch.2 Sec.4 [2]

Electrical and electronic equipment DNVGL-OS-D202 Ch.2 Sec.4 [3]

Pneumatic and hydraulic equipment DNVGL-OS-D202 Ch.2 Sec.4 [4]

5 User interfaceThe location and design of the user interface shall give consideration to the physical capabilities of theuser and comply with accepted ergonomic principles. This requirement affects workstation design andarrangement, user input devices and displays/ screens. Detailed requirements are given in DNVGL-OS-D202Ch.2 Sec.5 as detailed in Table 6.

Table 6

Description References in DNVGL-OS-D202

Workstation design and arrangement DNVGL-OS-D202 Ch.2 Sec.5 [2]

User input device and visual display unit design DNVGL-OS-D202 Ch.2 Sec.5 [3]

Screen based systems DNVGL-OS-D202 Ch.2 Sec.5 [4]

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6 ESD and emergency control

6.1 Emergency shut down

6.1.1 GeneralAn emergency shutdown (ESD) shall be provided following the requirements as given in the MODU code andfurther clarified by DNV GL interpretations as listed below.

6.1.2 InstallationIn order to meet the objective of ignition control in abnormal condition, an ESD system shall be provided tofacilitate the selective disconnection or shutdown of:

— ventilation systems, except fans necessary for supplying combustion air to prime movers for theproduction of electrical power;

— main generator prime movers, including the ventilation systems for these;— emergency generator prime movers.

(see MODU code 6.5.1)Interpretation:

All HVAC inlets without dedicated gas detection should be automatically shutdown immediately upon gas detection anywhere.Shutdown of HVAC implies trip of HVAC fan and close of relevant dampers. Individual HVAC inlets provided with dedicated gasdetection should be automatically shutdown immediately upon local gas detection.

Inlets for prime movers for production of electricity do not need to be individually tripped if they supply combustion air to theprime mover only. Combined HVAC- and combustion inlets do not need to be tripped if branch take-off to room ventilation can betripped.

---e-n-d---o-f---i-n-t-e-r-p-r-e-t-a-t-i-o-n---

6.1.3 OperationDisconnection or shutdown shall be possible from at least two strategic locations, one of which should beoutside hazardous areas.(see MODU code 6.5.3)

Interpretation:

Additional automatic inputs will be accepted.

Locations indicated in Table 7 should be applied as a basis.

Location of push buttons for manual shutdown

Table 7 Location of push buttons for manual shutdown

Shutdown level Location of push-button

Abandon vessel (AVS)

— main and emergency control rooms, i.e. bridge and back-up controlroom

— muster stations, lifeboat stations and helicopter deck— bridge connections between units/installations (if any)

Emergency shutdown (ESD)

As for AVS, plus (where applicable):

— process control room— driller’s control cabin— exits and main escape routes from process, drilling, wellhead, riser

areas etc.

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Shutdown level Location of push-button

Manually activated call point (MAC) Readily available for use in all normally manned areas (see DNVGL-OS-D301Ch.2 Sec.4 [3])


6.1.4 Unintentional stoppages/ inadvertent operationShutdown systems shall be so designed that the risk of unintentional stoppages caused by malfunction in ashutdown system and the risk of inadvertent operation of a shutdown are minimized.(see MODU code 6.5.4)

Interpretation:

The ESD system should be designed to allow testing without interrupting other systems onboard.

The ESD Operator Station/HMI unit should be located in a non-hazardous and continuously manned area.

The ESD control unit, comprising operator stations/HMI units and logic solver(s), should be powered as required by DNVGL-OS-D201 Ch.2 Sec.2, including a transitional source of power/ UPS.

The ESD system should have continuous availability R0 as defined in DNVGL-OS-D202 Ch.2 Sec.1 [2.2] and be regarded as asafety system. This implies that the system is both redundant and not vulnerable to a single failure or fail-safe on instrumentationfailure as is specified below. Components like valves and actuators, etc. are not required to be redundant.

Upon failure of the ESD system, all connected systems should default to the safest condition for the unit or installation. The safestconditions defined in Table 8 normally apply. The table is not intended to be comprehensive, so that other safety-related systemsshall also be considered in a similar way. The table is primarily intended for systems shutdown/operations and not individualcomponents within the system.

Failures to be considered for the shutdown system should include broken connections and short circuits on input and outputcircuits, loss of power supply and if relevant loss of communication with other systems. In this case, ‘circuit’ is defined as anysignal transfer facility, e.g. electrical, pneumatic, hydraulic, optical or acoustic.

Table 8 Safest conditions and corresponding output circuit configuration

SystemSafest condition in caseof failure to the shutdownsystem

Output circuitconfiguration

Fire pump drivers (start function) Operational NE

Electrical power generation, including required auxiliary systems,for units not dependent upon active position keeping Shut down 1) NE

Electrical power generation, including required auxiliary systems,for units dependent upon active position keeping Operational 1) NDE

Uninterruptible power supplies for power generation, control andsafety systems Operational 1) NDE

Propulsion and steering for units not dependent upon active positionkeeping Shut down 1) NE

Propulsion and steering for units dependent upon active positionkeeping Operational NDE

Fire dampers 2) Shutdown NE

Utility systems which do not affect safety functions Shut down NE

Drilling system Operational 3) NDE

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SystemSafest condition in caseof failure to the shutdownsystem

Output circuitconfiguration

1) Some installations may have multiple operational modes; e.g. storage units intended to transport crude oilto port. In such cases, the safest conditions for each operational mode shall be identified and implemented(e.g. through facilities for by-pass of high level ESD trips during transit).

2) For units dependent upon active position keeping, fire dampers in ventilation inlets for combustion air maybe NDE.

3) See DNVGL-OS-E101 for further details

The above principles apply for offshore operating condition. However, for mobile units in transit the requirementsin MODU Code sec. 14.8 or SOLAS Chapter II-/43 apply. This may imply that relevant ESD actions have to bepartially or completely disabled during transit.

NDE = normally de-energised NE = normally energised


6.1.5 Operational after shutdownEquipment which is located in spaces other than enclosed spaces and which is capable of operation aftershutdown shall be suitable for installation in zone 2 locations. Such equipment which is located in enclosedspaces should be suitable for its intended operation(See MODU code 6.5.5)

Interpretation:

The term ‘capable of operation after shutdown’ should be understood to mean ‘operational after ESD high level’.

It should be possible to isolate non-Ex equipment in naturally ventilated areas upon gas detection. The shutdown may be manualor automatic depending on the operational philosophy of the unit. Exemption is the equipment listed in [2.1.5].

Suitable equipment should be understood to be certified by an independent laboratory. If this is not possible, the suitable shouldbe assessed on a case-by-case basis.

Rooms with safety critical non-Ex equipment should have at least two doors towards outside areas effectively forming a semi-airlock. Spaces with only one barrier against gas ingress should have only Ex-equipment.

Typical living quarter design may meet this requirement, other enclosed spaces will be specially considered based on the aboveprinciples.

Unconfirmed gas detection should initiate alarm in the crane cabin. Non-operational cranes should be automatically de-energised ifhydrocarbon gas is detected anywhere. Operational cranes should be subject to manual isolation of uncertified electrical equipmentand other ignition sources after securing of load.

Confirmed gas detection at the crane ventilation intake should initiate automatic isolation of the crane.


Guidance note:

This early warning to crane operator should give the operator enough time to secure the load and avoid possible suspended load ifpower to crane is lost as a result of rapid escalation of the event.

For units with dedicated extract systems for shale shaker and mud tanks, gas detection from these systems does not require alarmto crane operator, neither tripping of welding sockets in non-essential temporary equipment as specified in Interpretation 3 resp. 5.


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At least the following facilities shall be operable after an emergency shutdown:

1) emergency lighting for half an hour2) general alarm system3) public address system4) battery-supplied radio communication installations5) blow-out preventer

(Ref. MODU code 6.5.5)Interpretation:

The safety critical systems listed may be non-Ex provided that the ventilation to the room where the equipment is located is shutdown and the room is efficiently isolated against gas ingress.

Since emergency lighting should be available for half an hour, there is no point in keeping the remaining items operable for longersince nobody can see anything and are assumed to have left the unit. Thus, 30 minutes would be sufficient.


Guidance note:

Item 4 of the requirement implies Ex-proof antennas for the applicable battery-supplied radio communications. Antennas with atransmission power below 6 Watts can be regarded as such (See IEC 60079-0, Sec.6.6.1). Item 4 does not require that all batterypowered radio communication remains operable.


6.2 Emergency control

6.2.1 Back-up means of operationWhere the normal user interface for the below listed safety functions is an operator station in an integratedsystem, a back-up means of operation/user interface is required.This applies to:

— emergency shutdown systems (ESD)— fire and gas detection system— activation of relevant fire-fighting systems— other safety functions where a back-up means is required by the rules or standards.

The back-up means of operation shall be independent of the normal user interface and its communicationnetworks.

Interpretation:

The back-up means of operation should be based on proven and reliable design and be:

— located adjacent to the normal operating position

— for all activation signals and other ESD related signals needed to ensure activation, hardwired individually directly to therespective controller.


Guidance note:

The back-up means of operation is typically achieved by provision of a CAAP (critical alarm and action panel).


6.2.2 Emergency control roomAt least two emergency control stations shall be provided. One of the stations shall be located near thedrilling console and the second station shall be at a suitable manned location outside the hazardous areas,normally on the bridge or CCR(See DNVGL-OS-A101 Ch.2 Sec.6 [2.5.1]).

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The control stations shall be provided with:

— manually operated contact makers for actuating the general alarm system— an efficient means of communication between these stations and all manned locations vital to the safety

of the vessel— emergency shutdown facilities.

(See DNVGL-OS-A101 Ch.2 Sec.6 [2.5.2])At least two BOP control panels shall be provided. One panel shall be located in the drilling control room andone panel shall be on the bridge/CCR or in the toolpusher’s office. For panels located outside the bridge/CCR,efficient means of communication between these locations and all manned locations vital to the safety of thevessel shall be provided.(See DNVGL-OS-A101 Ch.2 Sec.6 [2.5.3])

7 Communication and alarms

7.1 CommunicationThe required internal communication systems shall be capable of being supplied from the emergency sourceof power, for a period of at least 18 hours.A voice communication system shall be provided between the central jacking control station and a location ateach leg in self-elevating units.The unit or installation shall be equipped with a public address system. The alarm system may be combinedwith the public address system, provided that:

— alarms automatically override any other input— volume controls are automatically set for alarm sounding— all parts of the public address system (e.g. amplifiers, signal cables and loudspeakers) are made

redundant— redundant parts are located or routed separately— all loudspeakers are protected with fuses against short circuits.

7.2 AlarmsThe following distinctive alarms shall be provided where relevant:

— abandon unit— general emergency/muster covering fire and hydrocarbon gas detection— toxic gas (e.g. hydrogen sulphide) detection.

All alarms shall be indicated visually and audibly in the control center.The number of alarms during abnormal conditions shall be assessed and reduced as far as practicable byalarm processing/suppression techniques in order to have operator attention on the most critical alarms thatrequire operator action.The alarms shall be clearly audible at all locations on the unit or installation, and shall be easilydistinguishable. If noise in an area prevents the audible alarm being heard a visible means of alarm shall beprovided.See IMO Resolution A.830(19) Code on Alarms and Indicators, 1995 for details on priorities, grouping,locations and types, including colours, symbols etc.

Guidance note:

National authorities may have specific requirements deviating from the IMO Resolution. These will normally be acceptable forclassification purposes.


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Alarm to areas which are not regularly manned (e.g. cofferdams, tanks) may be covered by proceduralprecautions, e.g. using portable radios.Activation of the general alarm shall be possible from the main control stations, including navigation bridgeand radio room.Requirements for alarms in connection with watertight doors and release of hazardous fire extinguishingmedium are given in DNVGL-OS-C301 and DNVGL-OS-D301.The alarm system shall be regularly tested.

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SECTION 5 FIRE PROTECTION

1 General

1.1 IntroductionThis chapter provides principles for design, construction and installation of fire protection of offshore unitsand installations.Table 1 lists references required for a complete understanding of this chapter.


Reference Title

IMO MODU Code Code for the construction and equipment of Mobile Offshore Drilling Units, 2009

IMO FSS Code International Code for Fire Safety Systems





1.2 ApplicationA mobile offshore unit safety certificate is issued by an administration or authorized organization other thanDNV GL is accepted as evidence that the unit is in accordance with the requirements of this chapter.Where the administration has authorized DNV GL to issue the MOU safety certificates on its behalf, DNV GLwill give effect to the fire protection, detection and extinction requirements following the descriptions of thischapter.

1.3 Plans and data to be submittedA general overview of the required plans and analyses to be submitted is listed in Table 2. A more detailedoverview, tuned to the specific design and project scope can be obtained from DNV GL’s Nauticus ProductionSystem.



Fire resisting and non-combustible materials

M020 – Material specification, firerelated properties

Surface materials, insulation materials,primary deck coverings, textiles,furniture and bedding.

AP

G060 – Structural fire protectiondrawing APStructural fire protection

arrangementsV060 – Penetration drawings AP

Machinery space fire doors M020 – Material specification, firerelated properties AP

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Structural fire protection ofdrilling area structure Z110 – Data sheet AP

G130 – Cause and effect diagram APFire and gas detection andalarm systems G150 – Design philosophy AP

I200 – Control and monitoringsystem documentation AP

Fire detection and alarm system

Z030 – System arrangement plan AP

I200 – Control and monitoringsystem documentation AP

Hydrocarbon gas detection andalarm system, fixed

Z030 – System arrangement plan Detectors, call points and alarmdevices. AP


S030 – Capacity analysis APFire water system

Z030 – System arrangement plan AP

Machinery spaces fixed waterspraying fire extinguishingsystem

Drilling area water spraying fireextinguishing system

External surface protectionwater spraying system

G200 – Fixed fire extinguishingsystem documentation AP

Emergency escape G100 – Escape and evacuationstudy AP

Assembly station / musterstation / temporary refuge space Z030 – System Arrangement plan AP

Escape route G120 – Escape route drawing AP


2 PrinciplesA mobile offshore unit safety certificate issued by an administration or authorized organization other thanDNV GL is accepted as evidence that the unit is in accordance with the requirements of this chapter.Where the Administration has authorized DNV GL to issue the MOU safety certificates on its behalf, DNVGL will give effect to the fire protection, detection and extinction requirements following the descriptionsgiven in DNVGL-OS-D301 (principles, technical requirements and guidance for design, manufacturing andinstallation). This standard meets and is based on the regulations of the MODU code 2009. Wherever, theMODU code requirements leaves room for interpretation, the DNVGL-OS-D301 standard completes the codewith additional specific requirements.

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3 Passive fire protectionPassive fire protection is as required by MODU code 9.2, Structural fire protection. Specific requirements formachinery systems and equipment are given is DNVGL-OS-D101 Ch.2 Sec.1 [1.5]. Fire protection measuresfor cables are given in DNVGL-OS-D301 Ch.2 Sec.2 [4] and DNVGL-OS-D101 Ch.2 Sec.10 [3.4].Openings and penetrations in fire rated divisions shall be arranged so as to maintain the fire rating of thedivisions. Penetrations shall be approved for the actual divisions where they are to be installed.Openings in bulkheads of “H” class are in general to be avoided.

4 Fire fighting systems

4.1 Fire pumps, fire mains, hydrants and hosesMODU code Ch.9, Sec.7 applies for fire pumps, fire mains, hydrant and hoses with the following remarks:

— It is acceptable that the fire water system is supplied from a header supplied from a leg well suction rawwater system.

— If installed, the lowest water level to assure supply of water from each of any two fire hydrants, hosesand 19 mm nozzles while maintaining a minimum pressure of 0.35 N/mm2 at any hydrant for 15 minutes.Minimum tank capacity (below lowest automatically maintained water level) shall be 10 m3. Minimum oneof the raw water pumps shall be arranged for automatic operation.

Guidance note:

Minimum tank capacity to be compatible to fire water supply for all fire pump running modes as e.g. start-up in case thedimensional fire scenario.


— In interpretation of MODU code 9.7.17, use of GRE/GRP material in firewater ring main, we refer DNVGL-OS-D101 Ch.2 Sec.2 [2.5.5].

— In interpretation of MODU code 9.7.14, The isolating valves shall be provided for easy access of operation.Where the isolation valves are remotely operated, manual operation shall be possible locally.

For the self-elevating units, the following additional fire water supply measures shall be provided:

a) Water shall be supplied from sea water main filled by at least two submersible pumping systems. Onesystem failure will not put the other system(s) out of function, and

b) Water shall be supplied from drill water system while unit lifting or lowering. Water stored in the drillwater tank(s) is not less than 40 m3 plus engine cooling water consumptions before unit lifting orlowering. Alternatively, water may be supplied from buffer tank(s) in which sea water stored is not lessthe quantity as the above mentioned.

(See IACS D11.2.4)

4.2 Active fire protection of specific areasMODU code Ch.9, Sec.7 and SOLAS II-2 applies for active fire protection of specific areas likeaccommodations, service and working spaces and machinery spaces.More details on the installation requirements for active fire protection is given DNVGL-OS-D301 Ch.2 Sec.2and DNVGL-OS-D301 Ch.2 Sec.6 as follows:

Table 3 Installation requirements for active fire protection – references


Accommodation, service and working spaces and control stations DNVGL-OS-D301 Ch.2 Sec.2 [2.1]

Machinery spaces DNVGL-OS-D301 Ch.2 Sec.2 [2.2]

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Lockers containing flammable liquids DNVGL-OS-D301 Ch.2 Sec.2 [2.3]

Storage of gas cylinders DNVGL-OS-D301 Ch.2 Sec.2 [2.4]

Drilling areas DNVGL-OS-D301 Ch.2 Sec.6 [3.2]

Processing areas DNVGL-OS-D301 Ch.2 Sec.6 [3.3]

4.3 Fire fighting systems of specific typesRequirements for fire fighting systems based on MODU code Ch.9 Sec.7 and the relevant FSS code chapterscomplemented with interpretations, are given in the DNVGL-OS-D301 Ch.2 Sec.3 as follows:

Table 4


Fire water pump DNVGL-OS-D301 Ch.2 Sec.3 [2.2]

Fire main DNVGL-OS-D301 Ch.2 Sec.3 [2.3]

Fire hydrants and hoses DNVGL-OS-D301 Ch.2 Sec.3 [2.4]

Fixes gas fire fighting DNVGL-OS-D301 Ch.2 Sec.3 [3.1]

Fixed foam DNVGL-OS-D301 Ch.2 Sec.3 [3.2]

Water mist DNVGL-OS-D301 Ch.2 Sec.3 [3.3]

Deluge systems DNVGL-OS-D301 Ch.2 Sec.3 [3.4]

Sprinkler systems DNVGL-OS-D301 Ch.2 Sec.3 [3.5]

Monitors DNVGL-OS-D301 Ch.2 Sec.3 [3.5]

Portable equipment DNVGL-OS-D301 Ch.2 Sec.3 [4]

5 Fire and gas detection systemsIn line with the fixed automatic gas detection system requirement of MODU code 9.8.1, a permanentlyinstalled automatic system shall be provided for detection of:

— Hydrogen sulphide gas in the following areas:

— shale-shaker area— mud tank area— drill floor— above or in the mud flow line.

— Hydrocarbon gas in:

— hazardous areas, except in zone 0 and areas mechanically ventilated— ventilation outlets from hazardous areas having mechanical ventilation— intakes for ventilation air.

If single fire or gas detectors are used for each detection area, fail safe action should be taken on instrumentfailure, meaning confirmed fire or gas.

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Guidance note:

If shutdown logic requires no shutdown action on confirmed fire/gas detection, detector failure should also only give alarm withequal priority. Normally local HVAC should be tripped on gas detection in the inlets and then detector failure should also causeHVAC trip.


The detection system shall give both audible and visual alarm in the main control room and on the drill floor.The system is clearly to indicate where gas has been detected. Visual indication of the gas concentration shallbe given in the main control room.

6 EscapeAt least one escape route from the drilling derrick and from driller's cabin should lead directly to a safe placewithout requiring personnel entry to the central drill floor area. Otherwise as required in DNVGL-OS-A101Ch.2 Sec.5 as listed in Table 5.

Table 5

Description Reference in DNVGL-OS-A101

Escape routes DNVGL-OS-A101 Ch.2 Sec.5 [2]

Muster areas DNVGL-OS-A101 Ch.2 Sec.5 [3]

Emergency lighting DNVGL-OS-A101 Ch.2 Sec.5 [4]

Marking and warning signboards DNVGL-OS-A101 Ch.2 Sec.5 [5]

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SECTION 6 ENHANCED SYSTEMS

1 Introduction

1.1 GeneralThis chapter summarizes the specific requirements for the enhanced control & safety systems (ES) notationas identified in the previous chapters.

1.2 ObjectiveThe objective of the ES notation is to increase safety over MODU Code and main class safety level in a costeffective way.

1.3 ScopeES covers the following:

— enhanced ESD— fire safety systems— refrigeration plants— alarm philosophy.

All of the technical requirements as listed in this chapter come in addition to MODU Code 2009 and mainclass requirements as described in the remaining of this rule book.

1.4 ApplicationThe requirements for ES as listed in this section are only applicable for vessels with the voluntary classnotation ES.

1.5 Documentation requirementsDocumentation shall be submitted as required by Table 1.



Unit G130 – Cause and effect diagram AP

Unit Z050 – Design philosophy AP

For general requirements to documentation, including definition of the Info codes, see DNVGL-CG-0168Sec.1.For a full definition of the documentation types, see DNVGL-CG-0168 Sec.2.

2 Technical requirementsAll of the technical requirements as listed in Table 2 come in addition to MODU Code 2009 and main class andadditional service notation requirements as described in the remaining of this part.

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Table 2 Requirements applicable for ES only


Enhanced ESD DNVGL-OS-A101 Ch.3 Sec.1

Refrigeration plants DNVGL-OS-D101 Ch.3 Sec.1

Alarm philosophy DNVGL-OS-D202 Ch.3 Sec.1

Active fire protection for moon poolEnhanced fire protection

DNVGL-OS-D301 Ch.3 Sec.1

3 Certification of materials and componentsThere are no additional requirements for certification of materials and components.

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CHAPTER 6 CERTIFICATION

SECTION 1 PROCEDURES

1 IntroductionThe scope of classification requires that specified materials, components and systems intended for the vesselare certified according to the rules. The objective of certification shall ensure that materials, components andsystems used in vessels classed by DNV GL, comply with the rule requirements.

Guidance note:

The certification as discussed in this section does not include (top-side) modules, or other subcontracted parts like legs, pontoonsas may be part of the newbuilding process.


This chapter describes the different types of certification and the involvement of DNV GL.Table 1 lists references required for a complete understanding of this chapter.


Reference Title






Guidance note:

The systems subject to certification may be installed in (top-side) modules, or other subcontracted parts like legs, pontoons etc.Notwithstanding, the modules/ parts are not part of the material, component and system certification as described in this section,but are considered as part of the new-building process as described in Ch.7.


2 Certification typesCertification of materials, components and systems will be documented by the following types of documents:

— DNV GL product certificate (VL):A document signed by a surveyor of DNV GL stating:

— conformity with rule requirements— that tests are carried out on the certified product itself— that tests are made on samples taken from the certified product itself— that tests are performed in presence of the surveyor or in accordance with special agreements.

— Works certificate (W)A document signed by the manufacturer stating:

— conformity with rule requirements— that tests are carried out on the certified product itself— that tests are made on samples taken from the certified product itself

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— that tests are witnessed and signed by a qualified department of the manufacturers.

— Test report (TR)A document signed by the manufacturer stating:

— conformity with rule requirements— that tests are carried out on samples from the current production.

The applicable chapters and sections of the rules specify which of the above mentioned documents arerequired, how the products should be marked and which technical standards and requirements apply. Moredetails are given in Sec.2 .

3 Class involvementTo ensure an efficient, cost effective and correct certification process, a certification agreement shall normallybe established between DNV GL and the manufacturer of VL certified products. Such agreement may bepart of a manufacturing survey arrangement (MSA) and shall include information on the procedures forplan approval and survey and to specify information that shall be transferred between the customer and theSociety. A more detailed description plan approval, type approval, survey and MSA are given in DNVGL-RU-OU-0101 Ch.1 Sec.6 [2].Marine and machinery systems and equipment will be certified or classified based on the following mainactivities:

— design verification— equipment certification— survey during construction and installation— survey during commissioning and start-up.

4 Certification in operationWhen machinery components are renewed, such components should in general be delivered in accordancewith requirements as per valid rules at the time of newbuilding . (See DNVGL-RU-OU-0101 Ch.3 Sec.2[3.2.1]).

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SECTION 2 MACHINERY AND SYSTEM CERTIFICATION

1 GeneralThis chapter gives an overview of the certification requirements for machinery and systems.

2 PrinciplesEquipment shall be certified consistent with its functions and importance for safety, categorized as follows:

— Category I: equipment related to safety for which a DNV GL certificate is required.— Category II: equipment related to safety for which a works certificate prepared by the manufacturer is

accepted.

Equipment for non-essential systems does not need to be certified but shall be delivered with documentationas for equipment Cat. II.

Table 1

Cat 1A Cat 1B Cat 1C Cat 2A Cat 2B

ScopeD

S2 R2D

S1 R2S1 R2 R2 R1

Certificate /Document

VL VL VL W TR

D: Design reviewS1: Witness of final testing of completed product

S2: Survey during construction and witness of final testing of completed product

R1: Review of manufacturers documentation (typical for product)

R2: Review of manufacturers documentation (specific to product)

The extent of required survey by DNV GL shall be decided on the basis of manufacturer's QA/QC system,manufacturing survey arrangement (MSA) with DNV GL and type of fabrication methods.

Guidance note:

It should be noted that the scopes defined for category IA and IB are typical and adjustments may be required based onconsiderations such as:

— standard type approved products / MSA agreement

— complexity and size of a delivery

— previous experience with equipment type

— maturity and effectiveness of manufacturer's quality assurance system

— degree of subcontracting.


Equipment of category II is normally accepted on the basis of a works certificate prepared by themanufacturer. The certificate shall contain the following data as a minimum:

1) equipment specification or data sheet2) limitations with respect to operation of equipment3) statement (affidavit) from the manufacturer to confirm that the equipment has been constructed,

manufactured and tested according to the recognized methods, codes and standards. Test report to beincluded in work certificates for diesel engines.

4) A test repost (TR) may be issued based on testing carried out on samples from the current production ofequal products.

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Guidance note:

Independent test certificate or report for the equipment or approval certificate for manufacturing system may also be accepted.


3 Machinery systems and equipment

3.1 GeneralPiping and piping components shall be delivered with material certification in accordance with Table 2. Wherethe requirement calls for witness by 3rd party (certificate type 3.2) this shall be carried out by DNV GL.

Table 2

Type of documentation

Component MaterialClass ofpipingsystem

Nominaldiameter

[mm]

Designtemperature

[°C]3.2

certificate3.1

certificate2.2

report

I > 50 x

II, III > 50 xPipes 1)

I, II, III ≤ 50 x

> 400 xFlanges and bolts

≤ 400 x

> 100 > 400 xSteel I

≤ 100 > 400 x

> 100 ≤ 400 xI, II

≤ 100 ≤ 400 xSteel ornodularcast iron

III x

Cast iron III x

> 50 xI, II

≤ 50 x

Bodies of valvesand fittings1), sourcematerials of steelexpansion bellows,other pressurecontainingcomponents notconsidered aspressure vessels Copper

alloysIII x

I xPump housings

II, III x

2.2 Test report: Confirmation by the manufacturer that the supplied products fulfill the purchase specification, and testdata from regular production, not necessarily from products supplied 2.2

3.1 Inspection certificate (works certificate): Test results of all specified tests from samples taken from the productssupplied. Inspection and tests witnessed and signed by QA department 3.1

3.2 Inspection certificate (test certificate): As work certificate, inspection and tests witnessed and signed by QAdepartment and an independent third party body

1) Pipes and bodies of valves fitted on unit or installation's side and bottom and bodies of valves fitted on collisionbulkhead shall be provided with documentation as required for class II piping systems.

(Valves to hydraulic pressure tested in the presence of a surveyor)

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3.2 Miscellaneous mechanical componentsCertification requirement for miscellaneous machinery mechanical components are given in Table 3.

Table 3

Item Certification category

Boiler 1A

Condenser 2A

Boiler heat exchanger 1A

Pumps for boiler 1C

Boiler PSV 1C

Boiler spark arrestor 2B

Winches 1A

Hydraulic cylinders pD > 20 000 1) 1A

Hydraulic cylinders pD ≤ 20 000 2A

Compressor 2)

1) Hydraulic cylinders for cleating and manoeuvring of watertight doors and hatches shall be delivered with certificateof category 1A regardless of pressure and size. Cleating cylinders where the locking mechanism is placed inside thecylinder shall be type approved.

p = design pressure [bar]

D = internal diameter of cylinder tube [mm]2) Compressors to be certified in accordance with DNV rules for ships Pt.4 Ch.5 Sec.4.

3.3 Pressure vesselsCertification requirement for pressure vessels are given in Table 4.

Table 4

CategoryProperty Conditions

I 2) II

X

XPressure

Vacuum or external pressure X

Steam X

Toxic fluid X

Thermal oil XMedium

Liquids with flash point below 100°C X

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CategoryProperty Conditions

I 2) II

Flammable fluids with T > 150°C X

Other fluids with T > 220°C X

Compressed air/gas PV ≥ 1.5 X

σy 360 MPa (50 000 psi) or σt 515 MPa (75 000 psi) XMaterial

Where impact testing is required. X

Free standing structural storage tanks will be specially considered based on stored medium, volume and height. Thesemay be designed according to the requirements of DNVGL-OS-C101.

Normally category IA, however, limited class survey may be agreed upon with DNV GL based on manufacturer's QA/QCsystem, manufacturing survey arrangement (MSA) and fabrication methods.

P = internal design pressure in bar

Di = inside diameter in mm

V = volume in m3

T = design temperature

σy = specified yield strength

σt = specified ultimate tensile strength

3.4 Main and emergency powerCertification requirements for main and emergency power is given in Table 5.

Table 5

Component Category

Engines for main power, emergency power, auxiliary power 1A

The individual components within the equipment train and other auxiliary systems are to be certified as requiredelsewhere in the rules, e.g. HVAC, and fire protection.

Requirements for testing, inspection and documentation are described in DNV rules for ships Pt.4 Ch.3 Sec.1as detailed in Table 6.

Table 6


Certification of parts C200

Testing and inspection of parts C300

Inspection during assembly C400

Workshop testing D

Shipboard testing I

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3.5 Jacking machineryJacking machinery shall be certified to category 1A.Requirements for certification and testing of the jacking gears are described in DNV rules for ships Pt.4 Ch.4Sec.2 C as follows:

Table 7


Certification of parts C100

Pinion and wheels C200

Welded gear designs C300

Ancillaries C400

Assembling C500

3.6 Components in marine and machinery piping systemsCertification requirements for components in marine piping system is given in Table 8.

Table 8


Piping system items for main and emergency power

Fuel oil transfer pump 1C

Cooling system pump unit 1C

Valves

Valves for sea inlet or discharge with DN > 100 mm 1C

Valves with DN > 100 mm and p > 16 bar 1C

Non-standard valves 1B

Compressed air systems

Starting air compressors 1C

Pressure relief valves 2A

Ballast system

Ballast pumps 1C

Ballast control system 1A

Bilge and drain system

Bilge control system 2A

Bilge pumps 1C

Bilge ejectors 2A

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Strainers 2B

Strums and rose boxes 2B

Air and sounding systems

Air vent heads 1B

Tank level indicators 2A

Sounding control panel 1B

Striking plates 2B

Sounding rods 2B

Leak detection system 2B

Hydraulic control of safety critical valves etc.

Hydraulic control panel 1B

Pumps in hydraulic control system 1C

Hydraulic power pack 2A

Accumulators (pV > 150 kNm) 1B

Accumulators (others) 2A

Tanks for hydraulic fluid 2B

4 Electrical installationsElectrical equipment serving essential or important functions and cables shall be delivered with certificates asrequired by Table 9. Additional requirements to certification may be given by other relevant parts of the DNVGL offshore standards.Equipment covered by a valid type approval certificate is generally accepted without further designverification, unless otherwise stated in the certificate. A reference to the type approval certificate shallsubstitute the required documentation for DNV GL design assessment.A product certificate may be issued based on the type approval certificate and a product survey, unlessotherwise stated in the type approval certificate.

Table 9 Certification requirements

Equipment RatingDNV GL

certificate(VL)

Works certificate(W)

DNV GL typeapproval cert.

(TA)

Main and emergency switchboards all ratings X

≥ 100 kW/kVA XDistribution switchboards, motor starters,motor control centres, etc. ≥ 10 kW/kVA and

< 100 kW/kVAX

Generators4) and transformers ≥ 300 kVA X

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Equipment RatingDNV GL

certificate(VL)

Works certificate(W)

DNV GL typeapproval cert.

(TA)

≥ 100 kVA and< 300 kVA 1) 2) X X

≥ 10 kVA and< 100 kVA

X

≥ 300 kW X

≥ 100 kW and< 300 kW 1) 2) X X

Motors 4)

≥ 10 kW and< 100 kW

X

≥ 100 kW X

Semiconductor assemblies for motor drives ≥ 10 kW and< 100 kW

X

≥ 50 kVA XSemiconductor assemblies for UPSs or batterychargers < 50 kVA X

Cables 1), 2) all ratings X

Electrical equipment installed in hazardousareas 3) all ratings - - -

1) As an alternative to the acceptance based on a type approval certificate (TA) and a works certificate (W), theelectrical equipment will also be accepted on the basis of a DNV GL product certificate (VL).

2) All cables – except cables for internal use in electrical assemblies or short lengths on mechanical packages.3) All electrical installations in hazardous areas, and areas that may be become hazardous by accidental release of

explosive gas, shall comply with the requirements for certification and documentation given in DNVGL-OS-D201Ch.2 Sec.11 [2].

4) Material certificates for shafts shall be issued as required by DNVGL-OS-D101.5) Heat exchangers used in conjunction with certified electrical equipment, shall be certified as required for pressure

vessels, see DNVGL-OS-D101.

Electrical equipment required to be delivered with DNV GL product certificate shall be documented asdescribed in Table 10. For equipment covered by a valid DNV GL type approval certificate, this certificate mayspecify exceptions to document approval.



Cables E110 – Cable data sheet and designdrawing

For cables not having a DNV GL typeapproval. AP

Electric propulsion motorsShafting documentation as requiredin DNV rules for ships Pt.4 Ch.4Sec.1 A200

Shafting for electric propulsion motorsin mechanical propulsion line. AP

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Shaft generatorsShafting documentation as requiredin DNV rules for ships Pt.4 Ch.4Sec.1 A200

Shafting for electric generators inmechanical propulsion line. AP

E120 – Electrical data sheet, general FI

E140 – Assembly schedules andtechnical data AP

E150 – Strength calculation withrespect to short circuit

When designed sub-transient shortcircuit strength exceeds 50 kA r.m.s. FI

E160 – Internal arc withstandingreport High voltage switchboards only. FI

E170 – Electrical schematic drawing AP

E180 – Layout of electrical assembly FI

Main and emergencyswitchboards

E240 – Functional description forelectrical assemblies FI

E120 – Electrical data sheet, general AP

E130 – Electrical data sheet,semiconductor assemblies FI



E240 – Functional description forelectrical assemblies FI

Semi-conductor assemblies

Z120 – Test procedure atmanufacturer AP

E120 – Electrical data sheet, general AP


E150 – Strength calculation withrespect to short circuit

When designed sub-transient shortcircuit strength exceeds 50 kA r.m.s. FI

E160 – Internal arc withstandingreport High voltage switchboards only. FI

E170 – Electrical schematic drawing AP

Distribution switchboards,motor starters, motorcontrol centres, harmonicfilters etc.


I020 – Control system functionaldescription AP

I030 – Block diagram AP

I050 – Power supply arrangement AP

Systems for automatic startand stop of generator driversand for automatic operationof breakers.

I080 – Data sheet withenvironmental specifications AP

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Z120 – Test procedure atmanufacturer AP


5 Automation and control systemThe certification requirement of the various instrumented systems shall follow the same certificationrequirement as the equipment under control.Major units of equipment associated with essential and important control and monitoring systems, asspecified in the rules, shall be provided with a product certificate unless exemption is given in a DNV GLissued type approval certificate or the logic is simple and the failure mechanisms are easily understood.The above applies for computer based systems as well. For DNV GL type approved systems, additionaltesting is only required for the application software programming and function and where specified explicitlyin the type approval certificate.The certification procedure normally consists of:

1) Document evaluation

— review of documentation for the appropriate system.

2) Manufacturing survey (MS)

— survey of hardware and software.

3) Test of project specific application software.

4) Issue of a DNV GL product certificate.

Guidance note:

Type approval of systems includes hardware, operating system software, standard software modules and standard function blocks.If new software modules or function blocks are made, testing will be required. Application software is project specific and shall betested before the certificate can be issued.


The certification requirement of the various instrumented systems shall follow the same certificationrequirement as the system they control.Integrated control and safety system shall always be certified.

6 Fire protectionCategorization of safety critical equipment is given in Table 11. Equipment that is considered important forsafety, which is not listed, shall be categorized after special consideration.

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Table 11 Categorization of safety critical equipment

CategoryComponent

IA IB II Type approved

Fire dampers, penetrations X

Fire water pumps incl. drivers 2 X

Components in fire extinguishing system 1

Fire hose X

Hose reels and associated equipment X

Nozzles X

Monitors X

Fixed fire fighting installations X

Other fire-fighting installations, e.g. deluge, powder or systemsnot covered by IMO 3 X

Insulation materials in fire resisting divisions X

Fire rated doors X

Fire rated windows X

Fire and gas detectors X

Wheeled and portable extinguishing system X

Fire extinguishing media X1 To follow requirements as given in DNVGL-OS-D101 and/or type approval certificate.2 Fire water pump (directly driven) is considered Cat. IB. Fire water lift pump (not directly driven) of proven design maybe accepted by conformation of material, witness of testing and review of fabrication documentation.3 Normally function test to be carried out at yard.

7 Watertight/ weathertight integrityCertification requirements for components related to water- and weathertight integrity as given in DNVGL-OS-C301 Ch.3 Sec.1 [3.2] are listed in Table 12.

Table 12 Certification requirements for components related to water- and weathertight integrity

CategoryComponent

IA IB II

Watertight doors and hatch covers X

Weathertight doors and hatch covers1) X

Side scuttles and windows X

Automatic closing devices for air pipes X

Valves for sea inlet or discharge X

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CategoryComponent

IA IB II

Hydraulic system for watertight closing appliances X

Accumulator, hand pumps X

Control and monitoring systems for watertight closing appliances X

1) In addition to the work certificate a design approval performed by DNV GL is required.

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CHAPTER 7 NEWBUILDING SURVEY


1 OverviewThis part gives an overview of the class requirements as relevant for the building site.

2 StructureAfter the principles given in this chapter, Sec.2 continues with the required survey planning defining theclass involvement on site in the remaining of the new building process. Sec.3 thereafter describes classrequirements regarding fabrication and testing of the structure. Sec.4 continuous with a detailed descriptionof the class related work process during mechanical completion, testing and commissioning. Sec.5 concludeswith an overview of the deliverables from class after commissioning of the unit.For a complete understanding of this chapter is referred to the rules for drilling and supports units and thestandards and class guidelines as listed in Table 1.

Table 1 Overview of applicable standards and class guidelines

Reference Title

DNVGL-RU-OU-0101 Offshore drilling and support units



DNVGL-OS-C401 Fabrication and testing of offshore structures




DNVGL-OS-D301 Fire safety

DNVGL-CG-0169 Quality survey plan for offshore class newbuilding surveys

DNVGL-CG-0170 Offshore classification projects – testing and commissioning

3 PrinciplesBasis principles for the involvement of class during new building are given in DNVGL-RU-OU-0101 Ch.1 Sec.4and DNVGL-RU-OU-0101 Ch.1 Sec.5.

Table 2 Basis principles for the involvement of class during new building

Description Reference in DNVGL-RU-OU-0101

Requirements for builder or designer DNVGL-RU-OU-0101 Ch.1 Sec.4 [1.2]

Applicable rules DNVGL-RU-OU-0101 Ch.1 Sec.4 [1.3]

Plan approval DNVGL-RU-OU-0101 Ch.1 Sec.4 [1.4]

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Survey during constructions DNVGL-RU-OU-0101 Ch.1 Sec.4 [1.5], see Sec. 2 regardingplanning

Installation of systems and equipment DNVGL-RU-OU-0101 Ch.1 Sec.4 [1.6], see Sec. 4

Testing and commissioning DNVGL-RU-OU-0101 Ch.1 Sec.4 [1.7], see Sec. 4

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SECTION 2 SURVEY PLANNING

1 ObjectiveThe objectives of survey planning are to:

1) ascertain various activities that are necessary for the classification of a unit2) to identify customer’s, DNV GL’s and various standards and procedures that are applicable to those

activities3) to define the extent of involvement by the customer and DNV GL.

2 ScopeThis section applies to the offshore construction activities at any of the following:

1) customer’s construction facilities2) subcontractors at the customer’s construction facilities3) subcontractors at their own facilities or at other remote locations.

The survey scope covers all relevant parts of the built including (top-side) modules and/or other majorsubcontracted parts like legs, pontoons etc. This is irrespective of the locations where these parts may beconstructed.The survey scope nor this section does cover the certification of equipment and materials.

3 Quality survey plan

3.1 IntroductionThe objectives as listed above are met by the definition and further processing of a so called quality surveyplan (QSP). This QSP is defined after a review of the construction facility, and is further discussed and agreedduring a new-building survey planning-kick off meeting. These phases are discussed in more detail in theremaining of this section.

3.2 Review of the construction facilityDNV GL shall familiarize itself with the customer’s production facilities, management processes, and safetyprocedures. This familiarization shall take place prior to starting any fabrication or construction. Suchfamiliarization will take place under the following circumstances:

1) Where DNV GL has no recent experience at the construction facility (typically after a lapse of one year)or when a significant new infrastructure to the facility has been added

2) Where there has been a significant management or personnel restructuring, having an impact on theship or offshore construction processes or,

3) Where the builder contracts to construct a vessel of a different type or substantially different in design.

In order to assess compliance with specified rules, standards and regulations, the Society may requireadditional documentation and carry out an assessment of yard’s processes, systems, and personnel relatedto the classification projects. The results of the assessment should be used as a basis to decide on the extentof the involvement of surveyors of the Society. The extent of the classifications Society’s involvement for thesite survey activities shall be clearly documented in a so called quality survey plan (QSP). A draft format forsuch a plan is given in DNVGL-CG-0169 Table 4-1.Where DNV GL has no recent experience with new building activities at the builder’s construction facility orits subcontractors and/or when significant new infrastructure has been added, DNV GL may initiate an MPQAand evaluate the customer’s QA/QC-performance and set the initial survey scope on basis of the MPQA ratingmethodology.

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3.3 New building survey planning

3.3.1 Kick off meetingPrior to commencement of any new building project, the customer and DNV GL are to discuss at a kick-off meeting the survey activity items listed as documented during the review of the facility (see above).The purpose is to agree how the list of specific activities shown in DNVGL-CG-0169 Table 4-1 is sufficientlycomprehensive, to be adjusted, if necessary and to be addressed.A record of the meeting is to be made, based upon the contents of DNVGL-CG-0169 Table 4-1, (the tablecan be used as the record with comments made inserted in the appropriate column). The customer may beasked to agree to undertake ad hoc investigations during construction where areas of concern arise. DNV GLis to be kept informed of the progress of any investigation. Whenever an investigation is undertaken and, ifwarranted by the severity of the problem, the customer should suspend relevant construction activities untilcounteractive measures are satisfactorily implemented, reviewed and accepted by the Society.

3.3.2 Quality standardsConstruction quality standards for the hull structure, piping, electrical, HVAC and other disciplines during newbuilding project shall be properly listed in this document, reviewed and agreed during the kick-off meeting.

3.3.3 Survey extentIt shall be underscored that the QSP table is not exhaustive, and in cases where the QSP is incomplete and/or not necessarily covering all survey aspects, it shall be the prerogative of DNV GL to require such activities/items added.The QSP only covers survey activities and does not cover the technical interpretations of the statutoryrequirements or approval of plans, designs and manuals required by the Regulations.It should be noted that the level of DNV GL involvement indicated on the QSP takes account of the activitiesof others, and DNV GL reserves the right to adjust its level of involvement if reduced involvement by othersis experienced or if the requisite quality is not achieved.

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SECTION 3 FABRICATION OF STRUCTURES

1 PrinciplesThe principles of fabrication of structures are described in DNVGL-OS-C401 and are further detailed in theremaining of this chapter.

2 Technical provisionsTechnical provisions regarding the fabrication of structures are described in DNVGL-OS-C401 Ch.2 as detailedin Table 1.

Table 1


Welding procedures and qualification of welders DNVGL-OS-C401 Ch.2 Sec.1

Fabrication and tolerances DNVGL-OS-C401 Ch.2 Sec.2

Non-destructive testing DNVGL-OS-C401 Ch.2 Sec.3

Other tests DNVGL-OS-C401 Ch.2 Sec.4

Corrosion protection systems DNVGL-OS-C401 Ch.2 Sec.5

Bolts DNVGL-OS-C401 Ch.2 Sec.6 [2]

Mechanical fastening DNVGL-OS-C401 Ch.2 Sec.6 [3]

3 Certification and classificationWelding of special, primary and secondary structures for hull, welding of superstructure, and equipmentshall be carried out by certified approved welders, with approved welding consumables and at contractorsrecognised by DNV GL.Detailed requirements are given in DNVGL-OS-C401 Ch.2 as detailed in Table 2.

Table 2


Contractors DNVGL-OS-C401 Ch.2 Sec.3 [2.3]

Welding consumables DNVGL-OS-C401 Ch.2 Sec.3 [2.4]

Welding procedures and qualification of welders DNVGL-OS-C401 Ch.2 Sec.3 [2.5]

Corrosion protection systems DNVGL-OS-C401 Ch.2 Sec.3 [2.6]

Non-destructive testing DNVGL-OS-C401 Ch.2 Sec.3 [2.7]

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SECTION 4 COMMISSIONING PROCESS

1 IntroductionThis chapter provides an overview of the total commissioning process of a self-elevating units and theinvolvement of class in this process.

2 PrinciplesWhere specified by the rules, testing shall be carried out in the presence of a surveyor, and relatedrequirements for test programmes shall be observed.A test programme for harbour and jack-up trials shall be prepared by the customer and accepted by theSociety. The programme shall specify systems and components to be tested, and the testing procedure. TheSociety may, in order to verify rule compliance, request additional tests and/or data to be recorded.Procedures for pre-commissioning, testing and commissioning for all the systems onboard that are coveredby the scope of classification shall be prepared by the customer and accepted by the Society.The tests shall give evidence as to satisfactory operation and performance in accordance with the rules.When testing control and safety systems, failure modes shall be simulated as realistically as possible.The extent of participation in the mechanical completion and commission activities by the Society shall beclearly identified in the quality survey plan (QSP) submitted by the customer and accepted by the Society.The extent of participation is limited to ensure compliance with the requirement of classification rules andapplicable statutory requirements.Final acceptance of commissioning is the owner’s responsibility.

3 ProcessThe total commissioning process is described in DNVGL-CG-0170.

Table 1

Description Reference in DNVGL-CG-0170

Detailed design DNVGL-CG-0170 Sec.2 [1]

Mechanical completion DNVGL-CG-0170 Sec.2 [1]

Commissioning DNVGL-CG-0170 Sec.2 [1]

Integration testing DNVGL-CG-0170 Sec.2 [1]

Marine sea trial DNVGL-CG-0170 Sec.2 [1]

Delivery DNVGL-CG-0170 Sec.2 [1]

Hook up DNVGL-CG-0170 Sec.2 [1]

Operation DNVGL-CG-0170 Sec.2 [1]

4 Survey scope categoriesThe survey scope during testing and commissioning defining DNV GL’s involvement shall be categorized asfollows:

— Survey Category 1 – Statutory and essential systems for safety (normally increased attendance by DNVGL).

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— Survey Category 2 – Main systems / functionally important (for main and additional class notations extentis based on the yard’s experience and the effectiveness of yard’s QA/QC system).

— Survey Category 3 – Normally limited or no attendance required by surveyor.

Examples of tables detail the survey categorization of marine systems and drilling systems are given inDNVGL-CG-0170 App.C [3].

5 Test requirements related to marine, utility and safety systemsDetailed test requirements for marine, utility and safety systems are given in the different chapter 3 ofDNVGL-OS-D101, DNVGL-OS-D201, DNVGL-OS-D202 and DNVGL-OS-D301. An overview of these is given inDNVGL-CG-0170 App.F as listed in Table 2.

Table 2

Description Reference in DNVGL-CG-0170

Stability and watertight integrity DNVGL-CG-0170 App.F [1]

Fabrication and testing of offshore structures DNVGL-CG-0170 App.F [2]

Marine and machinery systems and equipment DNVGL-CG-0170 App.F [3]

Electrical installations DNVGL-CG-0170 App.F [4]

Instrumentation and telecommunication systems DNVGL-CG-0170 App.F [5]

Fire protection systems DNVGL-CG-0170 App.F [6]

6 Jacking trialsIn addition to the above a jacking trial shall performed according to an approved jacking trial plan and ascovered by the QSP. The trial shall cover the correct functioning of the jacking machinery and other relevantitems.The jacking machinery shall be tested with the highest specified design lifting load. The duration shall at leastreflect one operating cycle from transit condition to the top of the legs and down again. The jacking trial shallverify the alignment of the racks and pinions and guides.The following systems shall be tested:

— jacking brake arrangement— alarm and monitoring arrangement for the jacking machinery, supporting equipment and unit safety

during jacking— fail safe arrangement of the jacking machinery and any interlock safety arrangement— essential systems and equipment used for normal jacking operations.

After trials, the structure including leg footing connection, guides, jackhouses, jacking gear arrangement tobe surveyed to the satisfaction of the surveyor.

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SECTION 5 DELIVERABLES

1 Class certificateWhen DNV GL is satisfied that the requirements specified for the unit in question have been met, theappropriate class notation will be assigned and confirmed by the issuance of a classification certificate.Provided the requirements for retention of class are complied with, the certificate will normally have a validityof five years.

2 Conditions of classClass may be assigned with conditions of class.These conditions may apply for equipment subject to class approval not readily commissioned in accordancewith approved testing and commissioning procedures. The outstanding testing and commission proceduresshould be minor of nature.Conditions of class do not apply for critical systems e.g., fire fighting/detection, life-saving appliances andnavigational aids. If these are not commissioned, class and statutory certificates are typically not issued.

3 Appendix to class certificateAn appendix to the classification certificate will be issued stating assumptions for the assignment of class andrestrictions regarding the use of the vessel which were established or assumed at the time of assignment ofclass.The appendix to classification certificate shall be on board all vessels built to DNV GL's class.The appendix contains information on:

1) class notations and register information2) general and special assumptions related to the particular ship, which may include reference to

operational instructions.

4 Additional declarationsUpon request, declarations confirming compliance with the rules may be issued for hull, machinery or specificclass notations provided the Society's main class has been assigned.

5 Statutory certificatesThe Society undertakes statutory certification on behalf of flag administrations when and to the extent theSociety has been authorized to do so by the individual flag administration.Statutory certification includes inter alia approval, survey and the issuance of statutory certificates.When the Society acts on behalf of a flag administration, the Society follows international statutoryinstruments, IACS Unified Interpretations and DNV GL Statutory interpretations, and generally followsguidance issued by IMO in circulars etc. unless the flag administration has instructed the Society otherwise.It is assumed by the Society that required statutory surveys for vessels classed by the Society will be carriedout by the Society or by officers of the flag administration itself and that statutory certificates will be issuedby the Society or by the flag administration with the exceptions mentioned in the paragraphs below. TheSociety assumes the right to withdraw class if statutory certificates are not issued as described in thisparagraph.The Society may accept that safety management certificates (ISM Code) are issued by a third party that hasbeen authorized by the flag administration and complies with IMO Resolution A.739(18) and A.789(19).The Society may accept that international ship security certificates (ISPS Code) are issued by a third partythat has been authorized by the flag administration and complies with MSC/Circ.1074.

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The Society may accept that cargo ship safety radio certificates (SOLAS) are issued by a third party that hasbeen authorized by the flag administration.For a dual classed vessel, where the Society has not been authorized by the flag administration to issuestatutory certificates, the Society may accept that such certificates are issued by the dual class societyprovided the other class society is authorized by the flag administration.

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CHAPTER 8 CLASSIFICATION IN OPERATION


1 IntroductionThis part gives an overview of the survey and inspection of class during the operational phase, focusing onthe specific aspects affecting the safety and reliability of a self-elevating unit in operation.For a complete understanding of this chapter is referred to DNVGL-RU-OU-0101 and the standards andrecommended practices as listed in Table 1.


Reference Title

DNVGL-RU-OU-0101 Offshore drilling and support units


DNVGL-OS-C104 Structural design of self-elevating units - LRFD method


DNVGL-RP-C203 Fatigue design of offshore steel structures

DNVGL-RP-C301 Design, fabrication, operation and qualification of bonded repair of steel structures

DNVGL-RP-C302 Risk based corrosion management

DNVGL-RP-0001 Probabilistic methods for planning of inspection for fatigue cracks in offshore structures

2 ObjectiveThe objective of the classification in operation is to confirm that the vessel, machinery installations andequipment are maintained at a standard complying with the requirements of the rules and by that has anadequate level of safety and quality.

3 ScopeThe technical scope of the class in operation follows the scope as discussed in Ch.4 Sec.1 [2]. Additionaldetails describing the scope of involvement of class in operation are given in Sec.2 [2] of this part.Inspections for statutory certification are only performed if DNV GL is authorized to act on the behalf of thenational authorities on their behalf. This part does not include inspection details for these statutory surveys.

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SECTION 2 GENERAL PROVISIONS AND REQUIREMENTS FORSURVEYS

1 Conditions for retention of classThe general conditions for the retention of class are given in DNVGL-RU-OU-0101 Ch.1 Sec. 5.

Table 1 Conditions for the retention of class


General requirements DNVGL-RU-OU-0101 Ch.1 Sec.5 [1.1]

The customer’s obligations DNVGL-RU-OU-0101 Ch.1 Sec.5 [1.2]

Class society involvement DNVGL-RU-OU-0101 Ch.1 Sec.5 [2], see Sec.2 below for further details

Endorsement and renewal of class DNVGL-RU-OU-0101 Ch.1 Sec.5 [3]

Suspension and withdrawal of class DNVGL-RU-OU-0101 Ch.1 Sec.5 [4]

Change of owner or manager DNVGL-RU-OU-0101 Ch.1 Sec.5 [5]

Force majeure DNVGL-RU-OU-0101 Ch.1 Sec.5 [6]

2 Class involvement

2.1 GeneralThe involvement of class in operation is detailed in DNVGL-RU-OU-0101 Ch.1 Sec. 5.

Table 2 Involvement of class in operation


Applicable rules DNVGL-RU-OU-0101 Ch.1 Sec.5 [2.1]

Surveys DNVGL-RU-OU-0101 Ch.1 Sec.5 [2.2]

Conditions and memoranda DNVGL-RU-OU-0101 Ch.1 Sec.5 [2.3]

Survey reports and survey status DNVGL-RU-OU-0101 Ch.1 Sec.5 [2.4]

Damage and repairs DNVGL-RU-OU-0101 Ch.1 Sec.5 [2.5], see below

Conversion and alterations DNVGL-RU-OU-0101 Ch.1 Sec.5 [2.6]

Temporary equipment DNVGL-RU-OU-0101 Ch.1 Sec.5 [2.7], see below

2.2 Damage and repairsExcursions from the units design envelope e.g. punch through or rack phase difference, shall be reported.Repairs of the hull structure, machinery, systems or equipment covered by the rules shall be carried out byqualified personnel and in compliance with applicable rules, with good engineering practice and under thesupervision of a surveyor.

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Repairs as may be carried out without the attendance of a surveyor (e.g. during voyage) provided a repairplan is accepted by the Society in advance. A surveyor shall be called for acceptance of such repairs whencompleted.

2.3 Temporary equipmentThe Society shall be informed before the installation of temporary equipment as defined in Ch.1 Sec.5 [2].Temporary equipment covered by class scope shall be approved and certified in line with normal classprocedures as described in the previous parts.For temporary equipment outside class scope, it shall be confirmed that placement of this equipment onboard does not negatively affect the safety of the unit.

Guidance note:

The following is typically considered:

— escape ways shall not been blocked

— fire and gas system covers the temporary equipment

— equipment is covered by the ESD logic

— equipment’s load is within deck load limits

— definition of hazardous areas takes into account the temp. equipment

— interface to other systems covered by main class does not negatively affect their availability.


3 Special provisions for ageing units

3.1 GeneralSelf-elevating units with age exceeding their initial design life (in many cases 20 years) shall be subject toevaluation for special provisions for maintaining required safety level.

The special provisions for maintaining required safety level are related to fatigue and corrosion condition ofthe hull and supporting structure. Degradation mechanisms due to ageing effects related to other aspectssuch as marine systems have also to be given due consideration by owner through maintenance, and bysurveyors through regular surveys.

3.2 Corrosion measurements and condition of protective coatingIn the design of Jack-up units corrosion allowance is normally not included as the structure is consideredadequately protected against corrosion, e.g. by sacrificial anodes, impressed current and coating.The corrosion diminution criteria as given in DNVGL-CG-0172, shall be applied. Alternative methods may beaccepted in agreement with the Society.The condition of protection coating system and minimum measurements as given in Sec.4 [3.2] shall becarried out every 5-year period.Owner shall document that the corrosion protection of the unit's hull is adequate and in line with conditionsassumed in original design. The corrosion protection system shall be specially surveyed.

3.3 Fatigue utilization indexThe fatigue utilization index (FUI) is defined as the ratio between the effective operational time and thedocumented fatigue life.

If fatigue cracks have been found in a unit prior to the FUI reaching 1.0, and the findings are located withinfatigue sensitive areas of the unit, the owner shall assess structural details in these areas at latest prior tothe renewal survey for the 5-year period.

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Calculation of effective operational time shall be based on recorded operations history. For the purpose ofcalculating the FUI, the following may be assumed:

— contribution from operation in harsh environment, e.g. North Sea, North Atlantic and Canada, equalsactual operating time in such environment

— contribution from operation in other environments equals one third (1/3) of actual operating time in suchenvironments

— periods of lay-up and yard stay may be disregarded— for self-elevating units; contribution from transit operation.

Owner shall submit FUI or historical data allowing for calculation of FUI as part of the planning process priorfor renewal survey when the nominal age exceeds the documented fatigue life.The FUIs may be calculated separately and in detail for various parts of the unit such as:

— leg nodes— spud cans— jackhouse— deck structure.

The calculations may reflect the various degrees of bottom restraints and loading pattern resulting from thedeck being fixed at various levels during the operations history of the unit.

3.4 Follow up for FUI bigger than oneOperation of the unit may continue when the FUI exceeds 1.0 provided the required safety level of thevessel is maintained. If no fatigue cracks have been found in a vessel prior to the FUI reaching 1.0, or if anyfindings have been evaluated to have insignificant influence on the fatigue capacity, no special provisions willbe required until such cracks are detected.For a vessel with FUI > 1.0 and where cracks have been detected in fatigue sensitive areas, the requiredsafety level is in general considered satisfied either

— by increasing the inspection frequency (i.e. NDT scope with 2½ year interval) or— by performing a condition based assessment for the vessel.

Where a condition based assessment for the unit is performed, the procedure and method shall be approvedprior to the renewal survey for the next 5-year period. A guide for condition based inspection planning isgiven below.

Guidance note:

A condition based inspection planning is performed by judging the vessel based on the actual condition rather than on age in orderto maintain the required safety level. In this context a scope implementing all or parts of the following procedure can/should beperformed:

— Apply the results from a fatigue analysis. The detail level of the analysis will influence the results. Higher detail level reducesthe uncertainties and increases the confidence in the results and hence reduces the inspection frequency.

— Mapping of critical connections w.r.t. fatigue capacity, i.e. ranking of fatigue sensitive details.

— Identify details to be modified/upgraded w.r.t. fatigue strength.

— Determine required safety level – dependent on consequence and access for inspection.

— Apply the fatigue results in a risk based analysis (RBI) including historical data from inspections/findings and inspection qualityfor preparing the inspection program.

— Evaluate the result from inspections (findings) and/or analysis and perform modifications/improvements ensuring that theassociated risks are adequately controlled.

— Perform a continuous updating of the inspection plan based on inspection results.

The inspection plan obtained from a condition based approach is highly dependent on the method and procedure applied; includingthe confidence level of the parameters considered. Less confidence increases the probability of failure (PoF) and hence theinspection frequency will increase.


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The Society will issue a MO (memo to owner) stating the FUI and agreed compensating measures prior to therenewal survey for the 5-year period in which the FUI exceeds 1.0.Associated plans and procedures, i.e. condition based inspection plans applying risk based approach, shall beapproved by the Society. The scope of the improvement program will depend on the initial assessment andowner's plans for further use of the unit.Units which have undergone an assessment and improvement program as outlined above to the Society'ssatisfaction, will be surveyed based on the modified inspection program.

3.5 Additional inspectionsThe scope for survey of jacking gears as outlined in Sec.4 [3] shall be increase to 20% of jacking gear unitsbut not less than two units per leg.

4 Alternative survey arrangementsAlternative survey arrangements may be accepted as an option to applicable periodical surveys for mainclass.

Table 3 Alternative survey arrangements

Name Description Reference in DNVGL-RU-OU-0101

Machinery continuous Survey arrangement based on surveys of the machineryitems

DNVGL-RU-OU-0101 Ch.3 Sec.7[2.2]

Machinery PMS a survey arrangement based on a planned maintenancesystem (PMS)


Machinery PMS –reliability centred

Survey arrangement based on review of the companymanagement, a reliability centred maintenance (RCM)analysis and the implemented maintenance system.


Offshore conditionmonitoring

a survey arrangement based on use of an approvedservice supplier for execution of condition monitoring onrotating machinery and drilling equipment


Drilling equipmentsurvey arrangements

Alternative survey arrangements applicable for units withthe notation DRILL with the alternatives Continuous,PMS, RCM and CM

DNVGL-RU-OU-0101 Ch.3 Sec.7[3]

Structural continuousSurvey arrangement whereby the survey items in thehull list established for the unit are subject to separatesurveys with an interval of 5 years.


Structural integritymanagement

Classification compliance based on an approved andimplemented inspection system


5 Surveys performed by approved companiesParts of the periodical surveys may be carried out by companies approved by DNV GL. The survey partsperformed by such companies are listed in Table 4.

Guidance note:

Note that parts of the statutory surveys may be performed by approved companies as well. Examples are inspections on fireextinguishers, life-boat overhaul and life-rafts. Class is only involved in these services as long as authorised by flag to perform thestatutory surveys on their behalf.


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Table 4 Survey parts performed by approved companies


Thickness measurements DNVGL-RU-OU-0101 Ch.3 Sec.8 [1.2]

Bottom survey afloat DNVGL-RU-OU-0101 Ch.3 Sec.8 [1.3]

Non destructive examination DNVGL-RU-OU-0101 Ch.3 Sec.8 [1.4]

Condition monitoring DNVGL-RU-OU-0101 Ch.3 Sec.8 [1.6]

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SECTION 3 PREPARATION AND PLANNING

1 PreparationThe owner shall provide the necessary facilities for safe execution of surveys.Tanks and spaces shall be safe for access, i.e. gas freed, ventilated, cleaned and illuminated.For overall and close-up examination, means shall be provided to enable the surveyor to examine thestructure in a safe and practical way.

Guidance note:

However, the ROV can be used for cathodical protection measurements and scour surveys.


Additional requirements relevant for the execution of the survey are given in DNVGL-RU-OU-0101 Ch.3 Sec.2as listed in Table 1.

Table 1 Additional requirements relevant for the execution of the survey


Conditions for survey and access to structures DNVGL-RU-OU-0101 Ch.3 Sec.2 [2.1]

Survey extent DNVGL-RU-OU-0101 Ch.3 Sec.2 [2.2]

Repair of structural damage or deterioration DNVGL-RU-OU-0101 Ch.3 Sec.2 [2.3]

Maintenance and preparation for survey DNVGL-RU-OU-0101 Ch.3 Sec.2 [3.1]

Replacement of machinery components DNVGL-RU-OU-0101 Ch.3 Sec.2 [3.2]

Machinery certification DNVGL-RU-OU-0101 Ch.3 Sec.2 [3.3]

2 Planning

2.1 General

2.1.1 IntroductionAll units shall be subjected to periodical and specific surveys in order to confirm that the hull, machinery,equipment and systems remain in satisfactory condition and in compliance with approval or acceptedstandards.

2.1.2 Periodical surveysPeriodical surveys will belong to one of the following categories according to the level of surveyrequirements:

— annual survey— intermediate survey— complete survey.

The survey required in conjunction with issuance of a new class certificate is denoted renewal survey.Specific details regarding the definition of the surveys are given in DNVGL-RU-OU-0101 Ch.3 Sec.1 as listedin Table 2.

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Table 2 Periodical surveys


General DNVGL-RU-OU-0101 Ch.3 Sec.1 [2.1]

Postponement of periodical surveys DNVGL-RU-OU-0101 Ch.3 Sec.1 [2.2]

Survey of units out of commissioning DNVGL-RU-OU-0101 Ch.3 Sec.1 [2.3]

Survey schedules DNVGL-RU-OU-0101 Ch.3 Sec.1 [2.4]

The periodical survey covers systems and parts for:

— structure and equipment1)

— machinery and safety systems2)

— temporary equipment as defined in Ch.1 Sec.5.1) Excluding outside bottom, spudcan and underwater part of legs as covered by specific surveys (See alsoSec.5)2) Adjusted depending on the followed alternative survey schemes (see also Sec.2).Specific details on the extent are specified in the in-service inspection programme as discussed in [2.2].The survey may be performed on location provided that the structure, including submerged parts, can bethoroughly inspected as specified in the in-service inspection program. If required, underwater inspectionshall be in accordance with an approved procedure, and using approved personnel and equipment.

2.1.3 Specific surveysBesides the standard periodical surveys, the following specific surveys are defined:

— bottom survey (covering external hull) i.e. external barge/deck structure— spudcan and leg survey (covering spudcans and the underwater areas of legs, together with their

connections)— survey after ocean transit— surveys in relation to permanent installation.

Schedule and scope for these specific surveys are given in Sec.5.

2.2 In-service inspection program (IIP)

2.2.1 DNV GL will develop and maintain an in-service inspection program (IIP) which will contain thestructural items to be surveyed to satisfy the minimum requirements for retention of main class (1A1) andmandatory requirements due to service notations, excluding any additional class notations (e.g. specialequipment and systems notations and special feature notations).The IIP constitutes the formal basis for surveying structural items under main class and shall be completed tothe satisfaction of attending surveyor before the survey can be credited.

2.2.2 The in-service inspection program (IIP) is developed on the basis of a general, experience-based scopein combination with design and fabrication particulars for the actual unit as well as experience from in-servicesurveys of units of similar type.

Guidance note:

Ship-shaped offshore units are not subject to extended hull survey requirements (EHSR) or enhanced survey programs (as shownby the ESP class notation) as defined in the DNVGL rules for classification of ships.


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2.2.3 The default basic scope for development of IIP for MOU is given in Table 3. Depending on the level ofthe design documentation, the basic scope might be altered.If the design documents the structural fatigue utilisation with considerable margins, the basic requirementsfor NDT inspection can be modified / reduced compared to the basic scope.When the unit is operating in other environmental conditions than considered in the design, the inspectionscope might as well be modified / changed, accounting for the actual application of the unit.The owner/operator has the responsibility to provide the necessary documentation for class approval, whenmodification of the basic in-service inspection program is requested.

Guidance note:

The standard in-service inspection program (IIP) is a generic based program based on gained experience and accumulatedknowledge from years of MOUs (and ships) surveys.

This inspection plan – level 1 – development is a simple version of RBI (risk based inspection – where Risk = probability of failurex consequence of failure). This is what can be denoted “basic RBI”. This way of preparing the inspection program is used where thedesign and fabrication information is limited (i.e. class transfer).

The second level , qualitative RBI, is based on the above “basic RBI” with the addition of design and fabrication particulars forthe specific vessel. This might be detailed fatigue results, ultimate strength utilization, coating system applied etc. which will becombined as basis for preparing the in-service inspection plan. This approach is applied for units built according to DNV GL Rulesand standards where experience from construction yard and approval centre are applied in preparing the inspection plan.

The third level is to prepare the in-service inspection program using a quantitative, refined probabilistic approach whereuncertainties wrt. different parameters affecting degradation; i.e. related to fatigue, coating, corrosion and wear and tear areanalysed for determination of inspection intervals which secure the necessary safety level to be maintained.

The quantitative approach is performed as an advisory service as requested by owner/operator and the modified inspection plan isto be approved by class before being applied as the in-service inspection class plan.


2.2.4 The extent of examination specified in the referred tables may be modified based on designdocumentation evaluation, inspection results / crack history and experience with similar units /details.(defined as level 2 for the IIP)

2.2.5 The extent of examination specified in the referred tables may be refined by use of RBI methodologies.(defined as level 3 for the IIP)

Guidance note:

At the 1st annual or intermediate survey after construction, column-stabilised and self-elevating units may be subject toexamination of major structural components including non-destructive testing, as deemed necessary by the Society. If the Societydeems such survey to be necessary, the extent should be agreed to by the Society and the owner or client prior to commencementof the survey.

For further guidance on RBI see also DNVGL-RP-C210 Probabilistic methods for planning of inspection for fatigue cracks in offshorestructures and DNVGL-RP-C302 Risk based corrosion management.


2.2.6 Detailed locations for thickness gauging will be prepared based on the condition of the unit andfollowing the applicable tables in Sec.4 [3.2]. Measurements shall be recorded and stored in DNV GL’sstructure integrity management (SIM) tool.

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Table 3 Basic scope for development of IIP for self-elevating units

TYPE OF SURVEY

AS (see IACSz15 3.3.5) IS RS

INT EXT INT EXT INT EXT

V NDT V NDT V NDT V NDT V NDT V NDT

Special areas for inspection 1)

(SP) – connections:

SP1 Leg to spudcan6) X X A A A A

SP2 Leg nodes and splices above thewaterline X A A X 3, 9)

SP3 Connections of primary membersin jack house A A X A A

Leg guides (IACS Z15 3.3.6) X A A

SP4 Main barge girder/bulkheadconnections X X X X A A X

Plating in way of leg well (IACSZ15 3.3.6) A A

Attachments of:

SP5 Crane/gangway pedestals and topflange A A A X A X A A A A

SP6 Support of drill floor and cantilever A A A A

SP7 Windlass and anchor chain/wirefairleads C B C A A C 8)

SP8 Helideck support X X X C A X A C

SP9Other attachment/supportconnections, e.g. flare and lifeboat support structures.

X X X X A X A X

Primary areas for inspection (PR): 2)

PR1 Spudcans A A A

PR2 Legs X A A7) A

PR3 Jack houses A A A

PR4 Main barge (deck structure)girders/bulkheads X X A A

PR5 Drill floor with substructure andcantilever X X X X A A

PR6 Crane/gangway pedestal X A A A A A

PR7 Lifeboat platform structure A A A

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TYPE OF SURVEY

AS (see IACSz15 3.3.5) IS RS

INT EXT INT EXT INT EXT

V NDT V NDT V NDT V NDT V NDT V NDT

PR8 Helideck and flare supportstructure X X X A A A

PR9 Other support structures X X X X A A

A = 100% 5)

B = 50% 4)

C = 25% 4)

X = Spot check 2-5% 4)

V = Visual inspection including close visual inspection of special areas.

NDT = Non-destructive testing, normally magnetic particle inspection (MPI) and/or eddy current (ET) of selectedstress concentrations and fatigue sensitive details.

1) Special areas for inspection (SP) are those sections of the structure which are in way of critical load transfer point,stress concentrations, often special steel selection etc. see listing in Sec.4 [3.2.1].

2) Primary areas for inspection (PR) are elements which are essential to the overall structural integrity of the unit.

See listing in Sec.4 [3.2.1].3) At levels which have been in way of lower guided in operation, upper guides in transit and in way of spudcans.4) - of the total number of these parts.5) The inspection extent might be reduced (be less than 100%) if based on design documentation, see Sec.4 [3.2.1]

(above).6) See Sec.5 [3], Spudcan and leg survey.7) For plate type legs, square or circular; examine also the pin holes IACS Z15 2.3.3).8) May be waived if unit permanently operating on the field.9) Only for leg nodes above the waterline.

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SECTION 4 PERIODICAL SURVEYS

1 Annual survey

1.1 ScopeAn annual survey is a general survey of the hull and equipment, machinery and systems to confirm that theunit complies with the relevant rule requirements and is in satisfactorily maintained condition. The survey willnormally cover systems and parts for:

— structure and equipment— machinery and safety systems— temporary equipment as defined in Ch.1 Sec.1 [2.2].

The survey for the temporary equipment shall only confirm class involvement as specified in Ch.1 Sec.5[2.7].

Guidance note:

The survey extent with regard to structure should follow the unit specific IIP as described in Sec.3 [1.2].


1.2 Structure and equipment

1.2.1 GeneralAny material alterations to the unit (its structural arrangements, subdivision, superstructure, fittings,and closing appliances upon which the stability calculations or the load line assignment is based) shall besurveyed and the relevant documentation to be reviewed.(see IACS Z15 3.3.2)

Guidance note:

See Sec.4 [3.2] for the extend of thickness measurements.

See Sec.2 [2] for special provisions for ageing units.


1.2.2 Protective coatingCondition of protective coating to be reported on according to Table 1.

Table 1 Conditions of protective coating

Corrosion protection system

Normally a full hard coating, usually to be epoxy coating or equivalent. Other coatingsystems, which are neither soft nor semi-hard coatings, may be accepted providedthey are applied and maintained in compliance with the manufacturer's specification.

(See IACS UR Z7) However, soft and semi hard coatings, if already applied, maybe accepted as result of a condition based assessment including a review of theorganizational set-up to maintain adequate corrosion protection.

Coating condition “GOOD” Condition with only minor spot rusting.

Coating condition “FAIR”Condition with local breakdown at edges of stiffeners and weld connections and/orlight rusting over 20% or more of areas under consideration, but less than as definedfor POOR condition.

Coating condition “POOR” Condition with general breakdown of coating over 20% or more of areas or hard scaleat 10% or more of areas under consideration.

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For structures where original protective coatings are in GOOD condition, the extent of close-up examinationand thickness measurements may be specially considered.Special consideration as used in this context is taken to mean, as a minimum, that sufficient close-upexamination and thickness measurements are carried out to confirm the actual average condition of thestructure under the protective coating.For areas with general breakdown of the protective coating, close-up examination and thicknessmeasurements shall be carried out to an extent sufficient to determine both general and local corrosion levelsfollowing Table 2 as guidance.Special consideration as used in this context is taken to mean, as a minimum, that sufficient close-upexamination and thickness measurements are carried out to confirm the actual average condition of thestructure under the protective coating.The above also applies to tanks of stainless steel. If not otherwise specified, the same applies for recoatedstructures (by epoxy coating or equivalent, alternatively a type approved coating, e.g. semi-hard), providedthat the condition of the protective coating is in GOOD condition and that documentation is available statingthat:

— the scantlings were assessed and found satisfactory by a surveyor prior to re-coating— the coating was applied according to the manufacturer's recommendations.

Where the unit has an impressed current cathodic protection system, the annual overview readings from thesystem shall be examined.Condition of protective coating shall be reported on according Sec.4 [1.4.9]. For areas with generalbreakdown of the protective coating, close-up examination and thickness measurements shall be carried outto an extent sufficient to determine both general and local corrosion levels.

1.2.3 Thickness measurementsThe surveyor may require thickness measurements in any portion of the structure where signs of wastageare evident or in areas where wastage is normally found. The surveyor may extend the scope of thethickness measurements if considered necessary.The minimum requirements for thickness measurements is presented in Sec.3 Table 5.When thickness measurements are specified by the rules or required by the surveyor the measurements shallbe carried out to an extent sufficient to determine both general and local corrosion levels.Thickness measurements shall be carried out by a qualified company approved by the Society and witnessedby a surveyor (see also Sec.8 on Services by approved companies). This requires the surveyor to be onboard, while the measurements are taken, to the extent necessary to control the process.Where it is required to carry out thickness measurements of structures subject to close-up examination,these measurements shall be carried out simultaneously with the close-up examination. The surveyor shallreview the final thickness measurement report and countersign the cover page.Where substantial corrosion, as defined in Ch.1 Sec.1 [2] is found, additional thickness measurements shallbe taken to confirm the extent of substantial corrosion.Areas found with substantial corrosion, which are not repaired, shall be recorded for thickness measurementsat subsequent annual surveys.Suspect areas (substantial corrosion previously defined) or areas where substantial corrosion is found at thesurvey being carried out, shall have thickness measurements extended following Table 2 as guidance.

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Table 2 Thickness measurements, extent and pattern in way of areas with substantial corrosion,all ships

Area/ structural member Extent of measurement Pattern of measurement

Plating Suspect area and adjacent plates 5 points over 1 m2

Stiffeners Suspect area3 points in line across web3 points in line across flange

Ref: IACS UR Z7 Table II

1.2.4 Watertight/ weathertight integrityItems which are important for the reserve buoyancy in connection with stability of the unit shall be surveyed.The survey shall include inspection of external and internal closing appliances, ventilators, air pipes, sidescuttles etc., as well as an external inspection of scupper valves and sanitary valves.Remote controls and alarm systems for doors, hatches and watertight dampers shall be surveyed andfunction tested.(See IACS UR Z15 3.3.3)External and internal weather and watertight doors, hatches and dampers shall be examined and functiontested. Tightness test to be carried out if found necessary.The closing devices for all air intakes and openings into accommodation spaces, service spaces, machineryspaces, control stations and approved openings in superstructures and deckhouses shall be examined.Sea water inlets and discharges shall be examined from the internal side of the unit.It shall be checked as far as practically possible that draught marks are legible. Functionality and properworking of draught measurement gauges shall be confirmed.Manual and automatic fire doors and dampers shall be examined and function tested.Ventilation ducts and operation of ventilation including emergency stop for engine and boiler rooms to beverified.Emergency escape breathing device (EEBD) shall be verified in order.Means of protection of the crew, such as guard rails, bulwarks, walkways and lifelines to be examined.

Guidance note:

For units or installations subjected to annual load line inspections by DNV GL, the requirements in this sub section are consideredcovered by this inspection.

(see IACS Z15 3.3.3)


1.2.5 Towing systemAccessible and visible parts of the unit's permanent towing arrangement shall be inspected

1.2.6 Deck houses and means of escapeMeans of escape from working and accommodation spaces to muster location, helideck and lifeboatembarkation deck shall be verified in order.

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1.3 Machinery and safety systems

1.3.1 MachineryThe survey shall include examination of spaces for machinery, boilers and incinerators, and equipmentlocated therein, with particular attention to fire and explosion hazards.As the surveyor deems necessary, running tests and/or opening of machinery, tests of safety devices andequipment with verification of integrity/ function of:

— jacketed high pressure fuel injection piping system— shielding of flammable oil piping system— insulation of hot surfaces exceeding 220ºC— oil burning equipment on boilers, hot water heaters, incinerators and inert gas generators.

Remote shutdown for fuel-oil transfer service pumps and ventilating equipment, together with oil tank outletvalves where required to be capable of being remotely closed shall be proved satisfactory (quick closingvalves).(ref. IACS UR Z15, 2.8,2)Boilers shall be externally surveyed. The general condition of the boiler including mountings, piping andinsulation shall be ascertained and the surveyor may require opening, removal of insulation etc. if foundnecessary. Safety valves, instrumentation and automation systems shall be tested in operating conditionwhen found necessary by the surveyor.Helifuel systems shall be surveyed with particular attention to general cleanliness and maintenance withspecial attention to fire/explosion hazards.

1.3.2 Jacking systemThe brake torques of jacking machinery on self-elevating units shall be checked. Where provided, the fixationrack system shall also be checked.Spot check on oil sample records.

Guidance note:

The frequency of oil samples should follow OEM recommendations but typically twice per year for self-elevating self-propelled unitswith a high jacking frequency.


A visual examination of the hydraulic lifting system shall be carried out, where applicable.(See IACS Z15 3.3.5)

1.3.3 Hazardous areaIn hazardous areas the following equipment and systems shall be surveyed or tested:

— ventilation systems shall be function tested. The tests shall include emergency stop systems and alarmsfor lost ventilation

— self-closing gastight doors and airlocks including other openings or accesses— alarms and shutdown functions for pressurised equipment shall be function tested— gas detection equipment shall be function tested— electrical equipment shall be visually inspected with respect to general condition and spark/explosion

hazard— devices for monitoring of insulation resistance or earth leak monitoring including alarms— protection devices for combustion engines.

(See IACS Z15 3.5 and 3.7)

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1.3.4 Temporary equipmentTemporary equipment as defined in Sec.1 [1] shall be surveyed, see also Sec.2 [2.2].

1.3.5 Fire and gas systemsFor fire extinguishing systems the survey shall include:

— testing of the water fire fighting system i.e. fire pumps, fire mains, hydrants and hoses as deemednecessary

— verification of the non-portable and portable fire extinguishers and portable foam applicators— examination of the fireman's outfit— examination of the fixed fire extinguishing systems.

The following systems shall be surveyed and tested for correct functioning:

— fire detection system— gas detection system, both flammable and toxic— general alarm system and communication between control stations.

(see IACS UR Z15 3.5 and 3.7)

1.3.6 Electrical installationsFor electrical installations the survey shall include:

— examination of main source of electrical power with respect to general condition, fire hazard andpersonnel safety, i.e. generators, main switchboards, distribution boards, control gear, consumers,chargers and battery/UPS systems

— test of automatic start and connection to the switchboard of the stand-by generator set by initiatingshutdown of the running diesel generator causing black-out.

— inspection of insulation monitoring devices for all distribution systems. If in doubt of correct reading (ex. ifthe reading is infinity), the device shall be tested

— examination of cable installations with respect to general condition, support and physical protection— examination of emergency source of electrical power with respect to general condition, fire hazard,

personnel safety and function, i.e. generator, emergency switchboard, emergency distribution boards,control gear, chargers, emergency consumers and battery/ UPS systems

— check if any modifications are done in the electrical system— test of emergency power system, i.e. manual and automatic connection of generator/batteries to

emergency switchboards, alternative start methods.— it shall be verified that records of inspections and maintenance of Ex- installations in accordance with the

implemented maintenance system are kept available onboard.— verify that the document “Schedule of batteries” is kept up to date.

1.3.7 Control and monitoring systemsControl and monitoring systems for auxiliary machinery shall be surveyed including:

— electric power generation and distribution— steam generation— thermal oil heating— oil or gas burning equipment on incinerators, inert gas generators and hot water heaters.

The survey shall include:

— alarm functions— safety functions— remote control functions— automatic control and shutdown functions

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— remote back-up means of operation— manual override— electrical and mechanical condition, labels, signboards etc.— control panels and local indicating instruments— emergency lighting in engine room— communication systems— fire alarm and fire protection systems.— verification of the change handling process for control and monitoring systems, see DNVGL-OS-D202 Ch.2

Sec.3.

1.3.8 ESDEmergency shutdown facilities shall be surveyed and tested.

Guidance note:

If operations make it difficult to carry out testing, a low level ESD is sufficient to comply to the above. As an alternative, a reviewof ESD test records can be done.


1.3.9 Bilge systemThe bilge system and related subsystems shall be visually surveyed and tested.

1.3.10 Loading instrumentsIf a loading instrument or loading computer system is available onboard it shall be verified that the systemhas a valid certificate.It shall be documented that an annual check of the loading instrument/computer by running one of the testconditions has been carried out. If not, the surveyor shall verify the running of the test condition onboard.

1.4 DocumentationThe appendix to the classification certificate and the documents referred to therein, shall be verified and keptavailable onboard the unit.Any changes to the systems (new equipment and overhauls, repairs and modifications) shall be surveyed andthe relevant documentation to be reviewed.(See IACS Z15 3.3.2)The system for recording changes to the lightweight of the unit shall be surveyed.(Ref. MODU code 3.1.4)

Guidance note:

For more information and guidance with regards to lightweight control is referred to DNVGL-OTG-12 Lightweight monitoring andcontrol during the operational life-cycle.


The system for tank level measurement shall be surveyed, with regard to accuracy, operability andredundancy.Approved loading and stability information shall be verified available onboard. This information shall be thesame as required when the unit was assigned class with the Society or at a later conversion of the unit, inaccordance with the rule requirements applicable in each case. It shall be confirmed that the unit is operatingwithin its approved design envelope.For units that shall comply with SOLAS Reg. IX/2, irrespective of the issuing authority for the safetymanagement certificate (SMC), the surveyor will complete a list of evidence of possible safety managementsystem failures recorded on the occasion of the annual survey. The list will be submitted with the annualsurvey report.

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For units granted a survey arrangement based on an approved planned maintenance system (PMS), anannual survey of the PMS is required to prolong the validity of the arrangement. The purpose of this survey isto review and evaluate the previous period's maintenance activities and experience. The annual survey shallconsist of the following main elements:

a) The maintenance history will be examined in order to verify that the PMS has been operated according tothe intentions and that the system is kept up to date.

b) Evaluation of the maintenance history for main overhaul jobs on the components covered by thecontinuous machinery survey (CMS) scheme carried out since last annual survey.

c) Details of corrective actions on components in the CMS scheme shall be made available.d) If condition monitoring equipment is in use, function tests of this equipment and verification of the

calibration will be carried out as far as practicable and reasonable.

2 Intermediate survey


2.1.1 GeneralThe survey shall, in general, be carried out as the annual survey, but with extended visual inspection andnon-destructive testing of the structure as given in the in-service inspection programme (see Sec.3 [2.4]).

2.1.2 TanksFor rigs over 5 years, at least two representative hull pre-load tanks shall be inspected.(See IACS UR Z1, 4.3.3).For units over 10 years of age the survey of ballast tanks, sewage (black water) tanks and wastewater (greywater) tanks shall include:

— for integral tanks internal examination— representative ballast tanks (if used for transit) and at least two representative hull pre-load tanks— tanks with hard coating of internal structures recorded in GOOD condition at the previous renewal survey

may be specially considered based on a satisfactory external examination. The internal examination oftanks used in association with sewage treatment may be specially considered based on a satisfactoryexternal examination and provided that an internal inspection has been carried out in accordance withonboard maintenance system during the last 12 months and relevant records are provided and confirmed

— for independent tanks external examination including the tank supporting structures— thickness measurements shall be carried out as deemed necessary.

2.1.3 Legs above waterlineSurvey of the upper part of the legs is normally required as specified in the IIP. Protective coating to beevaluated.

2.1.4 Legs below waterline and spudcanSurvey of lower leg (leg part below water line), spudcan and leg/spudcan connection is defined within the“Spudcan and leg survey" in Sec.5 [3].Potential measurements will be required if found necessary.

2.2 Machinery and systemsAs per annual (see Sec.4 [1.2]).

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3 Renewal survey

3.1 ExtentThe extent of the survey includes the requirements of the annual and intermediate survey, the items as givenin the in-service inspection program as given in Sec.3 [2.4], and additionally the requirements as discussedin this chapter.Deficiencies shall normally be rectified before the renewal survey is regarded as completed. The Societymay accept that minor deficiencies, recorded as condition of class, are rectified within a specified time limit,normally not exceeding 3 months after the survey completion date.For units intended to stay on location for prolonged periods, see Sec.6.


3.2.1 Thickness measurementsThickness measurements shall in general be carried out as presented in Table 3.Areas where substantial corrosion is found at the survey being carried out, shall have thicknessmeasurements extended following Table 6.

Table 3 Minimum requirements for thickness measurements – self elevating units

Id. AreaRenewal survey

No.1

Age 0-5 years

Renewal surveyNo.2

Age 5-10 years

Renewal surveyNo.3

Age 10-15 years

Renewal surveyNo.4 and subsequent

Age >15 years

1 All Suspect areas Suspect areas Suspect areas Suspect areas

2Structural componentsof Special and Primarycategory

Areas withindication ofwastage

Areas withindication ofwastage

Areas with indicationof wastage

Areas with indicationof wastage

3 Legs

Representativechords andbracings/ plateand stiffenersin way of splashzone

Representativechords and bracings/plate and stiffenersin way of splash zoneand at connections tomat/ spudcan

Representative chordsand bracings/ plateand stiffeners in wayof splash zone and atconnections to mat/spudcan.Representative chordsand bracings/ plateand stiffeners in otherlevels

4

Mat or spudcanconnections to legs andmain structural bulkheadsof mat or spudcan

Representativeplates, bulkheadsand stiffeners

Representativeplates, bulkheads andstiffeners

All plates, bulkheadsand stiffeners

5

Jackhouse and loadtransfer area (externaland in way of preloadtanks) including leg wellsand lower guides

Representativeplates andstiffeners

Representative platesand stiffeners

All plates andstiffeners

6 Upper Hull exposed deckand bottom plating

Representativeplates Representative plates All plates

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Id. AreaRenewal survey

No.1

Age 0-5 years

Renewal surveyNo.2

Age 5-10 years

Renewal surveyNo.3

Age 10-15 years

Renewal surveyNo.4 and subsequent

Age >15 years

7Upper hull“Box” or “I” type sections

Main supporting structure



8 Preload tanks

Representativestructure ofone preload(seawater) tank

Representativestructure of twopreload (seawater)tanks

Representativestructure of all preload(seawater) tanks

9

Main supporting structureof heavy substructuresand equipment. e.g. cranepedestal, cantilever anddrill floor substructure,lifeboat platform andhelicopter deck

Representativeplating and stiffeners

Representative platingand stiffeners

10

Structural componentsof special or primarycategory other than under3 to 7 above(These areas are normallyidentified in the IIP)

Representativeplating and stiffeners

Representative platingand stiffeners

11 Air pipes and ventilators

Selected air pipesand ventilatorcoamings on exposedmain deck

All air pipes andventilator coamings onexposed main deck

12 Plating of sea chest All plating of sea chest

Notes:1) and 2) if considered necessary by the attending surveyor.

3) to 12) mandatory thickness measurements, number and extent of thickness measurement requirements may bemodified by the surveyor considering the corrosion protection condition and arrangements.

Guidance note:

Sample of structures prone to rapid wastage;

— Areas of legs without an efficient/intact hard epoxy coating system in way of the splash zone.

— Upper hull seawater tanks without an efficient/intact hard epoxy coating system.


Application categories for structural components to be inspected referred in the table above, are defined inSec.3 Table 3.Special areas for inspection:

— vertical columns in way of intersection with the mat structure (spudcan)— highly stressed elements of bottom of leg, including leg connection to spudcan or mat— intersections of lattice type leg structure, which incorporates novel construction, including the use of steel

castings— highly stressed elements of guide structures, jacking and locking system(s), jackhouse and support

structure

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— highly stressed elements of crane pedestals, etc. and their supporting structure.

Primary areas for inspection:

— combination of bulkhead, deck, side and bottom plating within the hull which form “Box” or “I” type mainsupporting structure

— all components of lattice type legs and external plating of cylindrical legs— jackhouse supporting structure and bottom footing structure, which receives initial transfer of load from

legs— internal bulkheads, shell and deck of spudcan or bottom mat supporting structures which are designed to

distribute major loads, either uniform or concentrated, into the mat structure.— main support structure of heavy substructures and equipment, e.g. cranes, drill floor substructure, life

boat platform and helicopter deck.

Other areas for inspection:

— deck, side and bottom plating of hull except areas where the structure is considered primary or specialapplication

— bulkheads, stiffeners, decks and girders in hull that are not considered as primary or special application— internal bulkheads and girders in cylindrical legs— internal bulkheads, stiffeners and girders of spudcan or bottom mat supporting structures except where

the structures are considered primary or special areas for inspection— in addition to the above, spot checks may be taken in other areas in order to assess the general condition

of the unit.Guidance note:

Recommended locations for the spot checks are the main deck (often problem area due to frequent deck loading/unloading) andpre-load tanks.


3.2.2 TanksAn overall examination, externally and internally, for excess wastage or damage of all spaces (all tanks),except fuel oil, lube oil and fresh water tanks, shall include all structures, piping systems outside machineryarea and sea connections in machinery area, i.e. plating and framing, bilges and drain wells, sounding,venting, pumping and drainage arrangements.For watertight integrity, see [3.2.5] below.(see IACS Z15 2.3.1)For sewage (black water) tanks and wastewater (grey water) tanks the survey shall include:

— For integral tanks internal examination.For units not exceeding 10 years of age the internal examination of tanks used in association with sewagetreatment may be specially considered (waived) based on a satisfactory external examination andprovided that an internal inspection has been carried out in accordance with onboard maintenance systemduring the last 12 months and relevant records are provided and confirmed.

— For independent tanks external examination including the tank supporting structures.Thickness measurements shall be carried out as deemed necessary.

Where provided, the condition of the corrosion prevention system of cargo oil tanks shall be examined.Examination of fuel oil, lube oil and fresh water tanks shall be in accordance with Table 6.Independent tanks in machinery spaces shall be externally examined including the tank supportingstructures.

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Table 4 Minimum requirements for internal examination of fuel oil, lube oil and fresh water tanks1) 2) 3)

Age of unit, yearsTank

0 to 5 5 to 10 10 to 15 above 15

Fuel oil/ diesel oil

Engine room/machinery space None None One One

Area outside engine room/machinery space None One Two 4) Half, minimum two 4)

Lube oil None None None One

Fresh water 5) None One All All

Notes:

1) Tanks of integral (structural) type.2) If a selection of tanks are accepted to be examined, then different tanks shall, as far as practicable, be examined at

each renewal survey, on a rotational basis.3) Peak tanks (all uses) are subject to internal examination at each renewal survey.4) At renewal surveys no 3 and subsequent surveys, one deep tank for fuel oil outside engine room shall be included, if

fitted.5) Tanks for clean fresh water, i.e. potable water, boiler water and other holding tanks for clean fresh water. Tanks for

mainly contaminated fresh water as waste water (grey water) and sewage (black water) shall be subject to internalexamination as given above.

(see IACS UR Z7)

3.2.3 Legs above waterlineSurvey of the upper part of the legs is normally required as specified in the IIP. Corrosion protection systemfor the legs to be surveyed, e.g. corrosion in splash zone and general corrosion of the legs.

3.2.4 Legs below waterline and spudcanSurvey of lower leg (leg part below water line), spudcan and leg/spudcan connection is defined within the“Spudcan and leg survey" in Sec.5 [3].

3.2.5 Watertight integrityWatertight integrity of tanks, bulkheads, hull, decks and other compartments is to be verified by visualinspection. (Z15 2.3.1).Suspect and/or critical structural areas should be examined and may be required to be tested for tightness,non-destructive tested or thickness gauged.Special arrangements related to stability such as watertight closing appliances for openings in internalbulkheads and decks, cross-flooding, counter-flooding etc., shall be examined and tested if necessary.Bulkhead shaft seals shall be verified. Dismantling shall be carried out where necessary to examine conditionof the bulkhead seal.

Guidance note:

Documented maintenance may be considered as a base for extent of dismantling.


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3.2.6 Testing of Structures and tanksPressure vessels, compartments and/or critical structural areas may be required pressure tested for tightnessif found necessary due to actual suspect status condition as evaluated at survey.Testing of structures forming boundaries of double bottom, deep tanks, peak tanks and other tanks, includingholds adapted for the carriage of water ballast, shall can be performed as given in the guidance note below.The surveyor may require further testing.Testing of other spaces not designed for the carriage of liquid may be omitted, provided a satisfactoryinternal examination together with an examination of the tank top is carried out.Independent tanks in machinery spaces shall be tested as deemed necessary.

Guidance note:

Tanks 1) to be tested Test head or pressure Remark

Ballast tanks Top of air pipe

Cargo holds adapted for carriage ofballast

Near the top of cargo hold hatch coaming 3)

Bilge water holding tanks Top of air pipe 2) alternatively as for fuel oil tanks

Fuel oil tanksHead of liquid to the highest point that liquid will rise underservice conditions

2), 3)

Lub. Oil tanksHead of liquid to the highest point that liquid will rise underservice conditions

2)

Fresh water tanksHead of liquid to the highest point that liquid will rise underservice conditions

2), 3)

Sewage (black and grey water)tanks

Top of air pipeAs deemed necessary by thesurveyor

Tanks containing other liquidsHead of liquid to the highest point that liquid will rise underservice conditions

As deemed necessary by thesurveyor

Notes:

1) Gravity tanks of integral type

2) Tanks within machinery spaces may be specially considered based on external examination of the tank boundaries and aconfirmation from the Master stating that no leakages or other defects have been observed during operation of the vessel.

3) Tanks within the cargo area may be specially considered based on a satisfactory external examination of the tankboundaries and a confirmation from the master stating that the pressure testing has been carried out according to therequirements with satisfactory results.


Remote level indicating systems for ballast tanks shall be surveyed and function tested.

3.2.7 Air pipe headsAir pipe heads on exposed decks shall be externally and internally examined following the guidance notebelow. According to the results of the examination, the surveyor may require examination of other air pipeheads.

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Guidance note:

1st renewal survey 2nd renewal survey 3rd renewal survey

Four randomly chosen, preferablyserving ballast tanks

25% of all the air pipes randomly chosen

all air pipe heads. Exemption may be consideredfor air pipe heads where there is substantiatedevidence of replacement within the previous fiveyears.


3.2.8 Piping systemsJetting piping systems or other external piping, particularly where penetrating mats or spud cans.(IACS UR Z15 2.3.3.)

3.2.9 Towing equipmentThe permanent towing arrangement of the unit shall be surveyed. Towing equipment is subject to visualinspection. NDT may be requested depending on condition and service history.

3.2.10 Other itemsSea chests and other sea inlets and discharges (above and below the waterline) with valves, includingsanitary valves and scupper valves, shall be opened for survey.Alternative survey methods may be accepted upon special consideration provided equivalency to opening upis achieved.

3.2.11 SignboardsThe presence of required signboards shall be verified.

3.2.12 Major appurtenancesFixation of major appurtenances to the main structure shall be surveyed. These may typically include cranepedestals, helicopter decks, drilling derricks, lifeboat platforms and heavy deck modules or skids.

3.3 Machinery and systems

3.3.1 MachinerySettling tank and daily service tanks for heavy fuel oil and diesel oil as well as lubrication oil circulation tanksassessed with respect to tank cleanliness.If inspection and cleaning have been carried out by the crew during the last 12 months and relevant logextracts are provided and confirmed, this may be credited as surveyed at the surveyor's discretion.Opening up of tanks may be required as found necessary by the surveyor.

3.3.2 Electrical installationsThe survey shall comprise examination of the electrical installations with regard to fire and explosion hazardsand injury from accidental touching. The survey is also to include testing of correct functioning of equipmentcovered by class requirements.As far as practicable, the following equipment shall be examined for satisfactory condition:

— main and emergency switchboards— generators— distribution boards— motor starters

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— electrical motors— converters (e.g. transformers, rectifiers, chargers)— cable installations— enclosures for electrical equipment— lighting equipment— heating equipment— battery installations.

The following tests shall be carried out to the extent deemed necessary by the surveyor to ascertain theproper functioning of the equipment:

— generator full load test; minimum load for life support and emergency jacking should be guaranteed— generator parallel operation— generator protection relays including non-important load trip, if fitted— generator remote speed control— generator synchronising equipment— power plant interlocking systems— insulation resistance indicating device— emergency generator including switchboards; auto start following loss of main supply— battery chargers— mechanical ventilation of battery rooms and lockers— electrical motors for essential and important use, e.g. for jacking system at full load— interlocking and/or alarms for pressurised rooms and equipment.— air systems and their redundancy as part of safety- or important systems.

Protection relays in generator and bus tie circuit breakers shall be tested with secondary current injection, orwith suitable apparatus made for testing of the installed protection units.Records of insulation test shall be shown to the surveyor. This requirement may be waived if:

— testing of all individual motors is included and logged in the planned maintenance system, and— the insulation monitoring alarms required by DNVGL-OS-D202 Ch.2 Sec.2 are integrated in the machinery

alarm.

3.3.3 Jacking systemThe jacking systems, including shock pads, shall be examined in the presence of the surveyor by the originalequipment manufacturer or other third party inspector mutually agreeable to the owner and the surveyor.A selected number of jacking gear units (about 20%, but not less than one unit per leg) shall be opened upfor inspection. Oil analysis shall be presented for all the jacking gear units.The inspection shall include the following:

a) racks and climbing pinions (visual examination for wear and proper tooth contact)b) planetary gear boxes (opening and visual examination of at least one per leg, oil analyses for all) (see

guidance note)c) linear gearboxes (can be inspected by means of endoscope or inspection covers when provided)d) braking systems (opening and visual examination of at least one per leg)e) pinions (pinion clearance if accessible)f) survey and NDT of jacking guides to the extent possible to be includedg) oil samples shall be collected directly after a jacking operation to ensure representative values.

Guidance note:

The above is specific for rack-pinion types of jacking systems. Alternative systems should have a comparable level of inspectionmaking sure the system is safe to operate for the next 5 year.


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For units with hydraulic cylinders for lifting the working and holding pins shall be examined by NDT. Theworking and holding yokes shall be tested for cracks by NDT.For self-elevating units, all parts of the legs shall be examined.

3.3.4 Raw water pumpsCheck availability of water supply for safety systems, i.e fire water for different operational conditions(transit, during jacking and in elevated conditions).

3.3.5 Hazardous areaEnclosed hazardous areas such as those containing open active mud tanks, shale shakers, de-gassers andde-sanders shall be examined and doors and closures in boundary bulkheads verified as effective.Ventilating systems including ductwork, fans, intake, exhaust locations for enclosed restricted areas andalarm system shall be examined, tested and proven satisfactory.Electrical equipment in hazardous areas shall be examined with respect to:

— corrosion— flameproof enclosure/ingress— no unauthorised modification— correct rating of lamps— earthing (spot check)— function testing of pressurised equipment and of associated alarms— testing of insulation resistance of power circuits (Ex p, Ex e and Ex n). Where proper records of testing are

maintained consideration may be given to accepting recent readings (maximum 12 months) by the ship'screw

— insulation monitors with alarms shall be function tested, if installed— for rooms protected by air locks, interlocking with ventilation of electrical supply to non-explosion

protected equipment and de-energising of such equipment in case of ventilation failure shall be examinedand function tested as applicable.Guidance note:

Megger testing may involve risk of explosion due to sparks. Therefore appropriate procedures for such work should be followed asrelevant e.g., “gas free certificate”.

Ex equipment to include Ex motors and Ex junction boxes and Ex enclosures.


3.3.6 Fire protection/ extinguishing/ preventionCorrect functioning of the various parts of the following systems shall, as far as applicable, be verified:

— alarm and safety system— fire and gas detection systems.

3.3.7 Instrumentation and automationWhen cancelling of automatic load reduction and/or automatic stop of engine are provided, these functionsshall be demonstrated to the surveyor.Emergency switch(es) for all electrical equipment including main and emergency generators, except alarmand communication systems and lighting in vital areas such as escape routes and landing platforms, shall beproved satisfactory (by a combination of testing and review of maintenance records).(see IACS UR Z15, 2.8.2)

Guidance note:

The above implies a complete test of the ESD system in the presence of DNV GL. Approved cause and effect diagrams should beavailable if possible.


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3.4 GeneralThe presence of required signboards shall be verified.

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SECTION 5 OTHER SURVEYS

1 GeneralPlans and procedures for these surveys shall be submitted for review in advance of the survey and madeavailable on board.

2 Bottom survey

2.1 GeneralThe bottom survey shall be taken two times in any five (5) year period, with an interval not exceeding three(3) years between examinations.Consideration may be given at the discretion of the Society and with acceptance of the flag to any specialcircumstances justifying an extension of the interval.The bottom survey afloat may replace the statutory dry-dock survey provided acceptance from the flag.Underwater inspection in lieu of dry-dock survey may not be acceptable where there is record of abnormaldeterioration or damage to the underwater structure; or where damage affecting the fitness of the unit isfound during the course of the survey.(See MODU Code 1.6.1.5 and 1.6.2.5).

Guidance note:

A bottom survey performed in elevated condition is considered a dry survey, hence no flag acceptance will be required.


2.2 ScopeExternal surfaces of underwater areas forming part of the buoyant volume when the unit is afloat, are to becovered. Spudcans and lower leg parts are excluded from the bottom survey scope and covered separately in[3].

Guidance note:

Non-metallic expansion joints in piping systems, if located in a system which penetrates the unit’s side and both the penetrationand the non-metallic expansion joint are located below the deepest load waterline, should be inspected as part of the bottomsurvey and replaced as necessary, or at an interval recommended by the manufacturer. (See MODU Code 4.11.3)


3 Spudcan and leg survey

3.1 GeneralThe spudcan and leg survey (below water line) is a part of the main class survey and consists of two (2)surveys in any five (5) year period; an intermediate survey and a renewal survey. The execution of thissurvey is independent of the class renewal and may be aligned with the unit’s operation.

Guidance note:

When the next renewal survey due date conflicts with the unit’s planned operation, the spud can and leg survey should be plannedfor being completed in advance when the relevant structure is accessible for survey.


Consideration may be given at the discretion of the Society to any special circumstances justifying anextension of the interval. (See also Sec.3 Table 2 and Sec.6).

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Guidance note:

An example of such a consideration is the spudcan and lower leg partly or completely under the mud line. In such a case the spudcan- leg survey may be postponed to the next rig move (see IACS UR Z15 2.3.3).


3.2 ScopeThe spudcan and leg survey includes the leg nodes below the water line and the spudcans.The nodes above the waterline are surveyed during the normal periodical surveys, as given in Sec.4 [2.1.4]and Sec.4 [3.2.3].Considerations shall be given to safe entry and accessibility of the spudcans before the survey, i.e.ventilation, arrangements for pumps, cables for lighting etc.

3.3 Intermediate surveyThe intermediate survey is a visual survey of the structure. The main purpose is to check for typicaldamages/defects.At the intermediate surveys after the second renewal survey, an evaluation of the lower leg (nodes), leg/spudcan connection, and the internal spudcan structure is to be performed (see IACS Z15 4.2.2).Condition based assessments documenting the actual condition of the lower leg and spudcan structure mayjustify waiving these parts from the survey. This documentation shall include the historical condition of thestructure at previous inspections with respect to degradation and previous repairs, frequency of rig moves,heavy landings on the seabed, any special circumstances or instances recorded by the owner/operator andpreferably recent footage of the structure.The condition based assessment is subject to a formal review by the class in advance.

3.4 Renewal surveyThe renewal survey is a thorough inspection of the spudcan, spudcan to leg connections, and leg nodes.External and internal surfaces of spudcans/mat, underwater areas of legs, together with their connectionsas applicable, shall be selectively cleaned to the satisfaction of the attending surveyor and examined. Visualexamination shall be supplemented by NDT on areas as identified in the in-service inspection plan. Forfurther guidance on scope, see Sec.3 Table 3.The cathodic protection system of the submerged zone shall be surveyed. The efficiency of the system for theforthcoming 5-year period shall be confirmed.The cathodic protection system shall be surveyed by visual inspection of sacrificial anodes and extent ofcorrosion. Corrosion in welds of vital parts which may be subject to fatigue shall be particularly considered.

4 Survey after ocean transitAfter an ocean transit, a survey shall ensure that the unit is in sound condition and did not suffer fromdamage from bad weather during the transit, otherwise consequences of inappropriate shimming of the legs.This post-transit survey applies both for wet and dry tows and shall be carried out before elevating the unit.The survey shall consist of the visual inspection and NDT testing with a focus on the following structuralareas:

— jackhouse structure and connection to the hull— leg nodes in way of upper/lower guides and chord spudcan connection— main deck area in way of support of gearboxes.

The owner shall prepare a survey plan including details of the tow to be submitted to the Society for approvalprior to commencement.The owner may perform the survey himself. If the survey reveals damage, DNV GL shall be involved in linewith Sec.2 [2.2]. If no damage are found, inspection records shall be shown at the next periodical survey.

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5 Surveys in relation to permanent installationSee Sec.6 [3] for requirements.

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SECTION 6 UPGRADES

1 Introduction

1.1 GeneralThe RENEW notation may be assigned to units where assessments and upgrades in accordance with therequirements of this section have been carried out.

1.2 ObjectiveThe objective of the RENEW(Structure) notation is to indicate that the legs, spudcans and jacking houseshas been reassessed with respect to fatigue and ultimate strength in the elevated survival condition, takinginto account the current condition of the unit, using up to date calculation tools. In order to minimise futurethickness diminution, the corrosion protection system shall be refurbished as found necessary.The objective of the RENEW(Systems) is to signify that the jacking and safety systems comply to theapplicable rules and standards in force at the date of issuance of the notation.

1.3 Scope

1.3.1 StructureThe scope of the notation covers the following main structures of the unit:

— legs— spud cans— leg-to-hull interface (including jackhouse).

1.3.2 SystemsThe scope may be further extended to the jacking system and the following safety systems:

— fire and gas detection— fire protection and extinguishing— emergency shutdown systems— PA & GA system.

Guidance note:

It is underlined that not all safety related components and systems are covered by the notation. Examples are life savingequipment (as covered by statutory requirements/ MODU code) and constructional fire protection.


1.4 Application

1.4.1 This notation applies for units planned for structural design life extensions and system upgrades.Guidance note:

The notation is independent from the execution of a 5-yearly renewal survey. Notwithstanding, it may be advantageous to plan fora parallel approach where the upgrades and life time extensions are performed during the renewal survey.


1.4.2 The notation is applied with the qualifiers as listed in Table 1.

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Table 1

Class notation Description Qualifier Description

(YYYY) Year when the notation was requested

(Structure) Scope of notation covers structural integrity as described in [2]RENEWAs per objectivedescription (see[1.2])

(Systems) Scope of notation covers jacking and safety systems asdescribed in [3] (voluntary)

1.4.3 The notation shall be maintained, subject to the follow up as defined in [4].

1.4.4 The standards applied for the RENEW notation shall be of the revision in force at the date thenotation was requested. (See also Ch.2 Sec.1 [2]).

1.5 Documentation requirements

1.5.1 GeneralA general overview of the document to be submitted to document compliance to the notation is listed below.

1.5.2 Structure

i) general arrangementii) main scantling drawings of hull, legs, spudcans and jackhousesiii) corrosion protection arrangementiv) jacking system specificationv) thickness gauging and survey reportsvi) global strength analysisvii) historical operational records including metocean data, soil conditions (leg footing penetrations and

moment fixities), water depths and air gapsviii) original design basis (i.e. design philosophy documents) and operating manual.

1.5.3 SystemThe documentation for the safety and jacking systems to be upgraded shall follow Table 4 of DNVGL-OS-D202 Ch.3 and DNVGL-OS-D101 Ch.2 Sec.5 where applicable.For jacking systems, a failure mode and effect analysis (FMEA) according to DNVGL-OS-D202 Ch.3 Sec.1Table 4 is to be carried out.

Guidance note:

In case the systems have been upgraded in recent years, the above may be replaced by the records connected to these upgrades,e.g. previous approval letters, certificates and design basis applied


2 Structure

2.1 SurveyThe special and primary areas of structures shall be inspected based on renewal survey requirement of Sec.4[3.2].

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Guidance note:

The requirement may be combined with 5-yearly renewal survey and can be exempted in case the renewal survey has beenperformed less than one year ago.


2.2 Ultimate limit stateThe strength of legs, spudcans, leg to hull interface and the capacity of the leg-to-hull holding (i.e. fixation)system shall be documented based on DNVGL-OS-C104 taken into account measured thicknesses.

Guidance note:

1) The scope of measurements required to obtain a sufficient basis as input to the analysis should be made in agreement withclass and will be depending on the condition of the unit.

2) The existing environmental limitations as defined for the unit may be modified to meet the requirements to ultimate strength.


2.3 Fatigue limit state

2.3.1 AssessmentThe legs, spudcans, and leg to hull interface shall be documented for a minimum remaining fatigue life of10 years taking into account previous operational history. The calculations shall incorporate the effect ofcorrosion throughout the life time and shall be based on DNVGL-OS-C104.

Guidance note:

The in service survey scope may be adjusted based on the findings of the fatigue analysis.

Gross scantlings may be utilized in the calculation of hull structural strength, provided a corrosion protection system in accordancewith DNVGL-OS-C101 Ch.2 Sec.9 is installed and maintained


2.3.2 Renewal and local improvementsSuitable measures shall be made for all items where the fatigue analysis have revealed a remaining expectedfatigue life less than the required extended life time.

Guidance note:

Measures to improve fatigue life may consist of local improvements of geometry to reduce stress concentrations, cropping andreplacing or local improvements of welds.


2.4 Corrosion

2.4.1 Corrosion marginsThickness diminutions shall be assessed and meet the requirements of DNVGL class guideline, DNVGL-CG-0172 Thickness diminution for mobile offshore units.A corrosion margin taking into account corrosion for the future operation according to DNVGL-CG-0172 shallbe added to structural members which are substantially corroded.

2.4.2 Corrosion protection systemStructural members within the scope of the notation with a coating condition ”FAIR” or lower as defined inSec.4, shall be cleaned and protected against further corrosion in accordance with DNVGL-OS-C101 Ch. 2Sec. 9.

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3 Systems

3.1 SurveyThe systems shall be inspected based on renewal survey requirement of Sec.4 [3.3].

Guidance note:

The requirement may be combined with 5-yearly renewal survey and can be exempted if the renewal survey has been executedless than one year ago.


3.2 Safety systemsThe safety systems as listed in [1.3.2] shall be upgraded to the applicable offshore standard. Existing, earlierupgraded systems may be accepted provided their compliance to the latest standards can be documented,i.e. by a gap analyse between design standards as applied vs existing standards.

Guidance note:

For existing systems, gaps with no/minor impact on safety shall be further documented as equivalent solution.

Gaps with a major impact shall be compensated by system upgrades.


3.3 Jacking systems

3.3.1 AnalyseJacking systems shall be evaluated against their remaining life cycle and capacity taking into accountinspection results, in particular:

— wear— cracks— overall condition.

When the evaluation indicates an operational use beyond 80% of the rated life of the jacking system, thelimiting environmental conditions and pinion capacity shall be re-established, alternatively the applicablecomponents shall be replaced.

3.3.2 UpgradesThe jacking control system shall be upgraded to the following safety critical requirements in case GAPanalysis shows non-compliance (based on IMO MODU Code 2009 and Ch.5 Sec.1 [6.6]):

— The jacking system shall be operable from a central jacking control station.— The jacking system shall include the following control and monitoring arrangements, when applicable:

— Remote indication and alarm if a brake is not released when power applied to the motors. The brakealarm shall be given by an independent mechanical sensor.

— Remote indication and alarm for overheating of an electric motor.— A permanent remote indication of loads during jacking and retrieval shall be provided. For a lattice leg

unit the load per chord is as a minimum to be presented. Alarm signal to be given when maximum loadis exceeded.

— Audible and visible alarm to indicate out-of-level (indication of inclination)— Audible and visible alarm to indicate rack phase differential (RPD) (if applicable).— Indication of power consumption

— A communication system should be provided between the central jacking control and a location at eachleg.

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3.4 Additional systemsAdditional systems upgraded will be listed in the appendix to class provided these comply to the latestapplicable offshore standard and are covered by the classification scope of the unit.

Guidance note:

For an overview of systems as covered by the class scope, see Ch.2.


4 RetentionThe retention of the RENEW notation for units in operation follow the principles and requirements of thischapter with the following remarks:

— The special provisions for ageing units in Sec.2 [3] are not applicable for the period covered by thestructural assessments from [2] (e.g. 10 years)

— The In-service inspection program as described in Sec.3 [2.4] will be adjusted based on the assessmentresults

— Requirements of periodical surveys related to a unit’s age as described in Sec.4 will be adjusted based onthe actual replaced/ upgraded parts.

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SECTION 7 PERMANENTLY INSTALLED SELF-ELEVATING UNITS

1 IntroductionThe requirements and guidance given in this chapter are supplementary requirements for units that areintended to stay on location for prolonged periods, normally more than 5 years.Permanently installed self-elevating units shall be designed or documented for the site specific environmentaland soil conditions. Fatigue properties and facilities for survey on location shall be specially considered.Adequate corrosion protection shall be implemented to cover the entire prolonged operation period.

2 FatigueDesign fatigue factors (DFF) are introduced as fatigue safety factors. DFF shall be applied to structuralelements according to the principles in DNVGL-OS-C104 App.A and /or DNVGL-OS-C201 App.C.

3 Inspection and maintenance

3.1 Facilities for surveySurveys may be carried out on location based on agreed procedures outlined in a maintenance system andsurvey arrangement, without interrupting the function of the unit. The following matters shall be taken intoconsideration to be able to carry out surveys on location:

— arrangements and methods for survey of hull, legs and seabed foundation structure— corrosion protection of hull, legs and seabed foundation structure— underwater cleaning facilities.

3.2 SurveysSurveys for permanently installed units follow the same approach as described in the previous chapters withthe following remarks:

— The in service inspection program (IIP) should reflect possible stress concentrations in critical areas,fatigue criticality, and the previous operational and inspection histories.

— Provided the fatigue analysis as described in [1] justifies integrity during the installation period, theSpudcan and Leg survey is limited to the accessible structure above the mudline.

— Provided the unit has arrangements for a fix load transfer by a permanent fixation system, the jackingsystem will be excluded from survey after the initial jacking of the unit.

Requirements for surveys when structural parts are designed without planning inspection are given inDNVGL-OS-C104 App.A.

3.3 Inspection before re-locationPermanent installed units planned for a re-location shall have a survey prior to movement. The survey scopeshall include the jacking system.Before re-location, an analyse shall document that the unit’s structural strength taken into account the newlocation’ environmental and soil conditions is sufficient for the remaining life time.A complete spudcan and leg survey as described in shall be completed before re-location.

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CHANGES - HISTORIC

July 2015 edition

Main changes July 2015

• GeneralThe revision of this document is part of the DNV GL merger, updating the previous DNV service specificationinto a DNV GL format including updated nomenclature and document reference numbering, e.g.:

— Main class identification 1A1 becomes 1A.— DNV replaced by DNV GL.— DNV-RP-A201 to DNVGL-CG-0168. A complete listing with updated reference numbers can be found on

DNV GL's homepage on internet.

As a part of the formatting the original document structure consisting of parts, chapters, sections etc. havebeen updated to chapters, sections and sub-sections etc. (with Pt.0 becoming Ch.1, Pt.1 becoming Ch.2etc.).To complete your understanding, observe that the entire DNV GL update process will be implementedsequentially. Hence, for some of the references, still the legacy DNV documents apply and are explicitlyindicated as such, e.g.: Rules for Ships has become DNV Rules for Ships.

• Ch.4 Sec.1 Structural design— [6.1.1]: Fixation system has been included in items described by the OS-C104 and C201.— [6.4]: 'Single' has been included in 3rd paragraph “In case of single failures”.

• Ch.7 Sec.4 Commissioning process— [2.1.1]: Removal of thickness measurements requirements for intermediate surveys.

• Ch.8 Sec.2 General provisions and requirements for surveys— [3.4]: Description of follow up inspections for units FUI > 1 has been updated.

• Ch.8 Sec.3 Preparation and planning— [2.4]: Corrections/ completions on IIP table and update of guidance note.

• Ch.8 Sec.4 Periodical surveys— [1.2.1]: Requirement on quick closing valves has been updated to align with IACS UR Z15 2.8.2.— [1.2.10]: A new clause on loading instruments survey requirements has been added.— [3.2.2]: Description has been updated in line with general systematics.— [3.3.7]: Survey requirement for remote shutdown of fuel transfer system has been deleted.

DNV GLDriven by our purpose of safeguarding life, property and the environment, DNV GL enablesorganizations to advance the safety and sustainability of their business. We provide classification andtechnical assurance along with software and independent expert advisory services to the maritime,oil and gas, and energy industries. We also provide certification services to customers across a widerange of industries. Operating in more than 100 countries, our 16 000 professionals are dedicated tohelping our customers make the world safer, smarter and greener.

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Documents

RULES FOR CLASSIFICATION Offshore units · FOREWORD DNV GL rules for classification contain procedural and technical requirements related to obtaining and retaining a class certificate