HEN-0000-ST-SP-0002

Hengam Offshore Development Project EPCI For

Topsides and Infield Pipelines and Subsea Cables

Contract No. 4405-90-2FG

STRUCTURAL FABRICATION SPECIFICATION Rev. B4

Proj. Area. Disc Doc. Seq. Page

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STRUCTURAL FABRICATION

SPECIFICATION

B4 18.Oct.2013 Re-Issue as AFD J.W.LIM PUREE ARUN H.KARIMI

B3 12.Mar.2013 Re-Issue as AFD S.M.ROH M.Y.SHIN Puree

B2 07.Jan.2013 Approved for

Design S.M.ROH M.Y.SHIN

B1 21.Sep.2012 Issued for Approval

S.M.ROH M.Y.SHIN

B0 11.Jul.2012 Issued for Comment

S.M.ROH M.Y.SHIN

Rev. Date Purpose of Issue Prep. Checked/Approved Approve Approve

ISI / Ocean Development GS Offshore IOOC






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Table of Contents

1. GENERAL ................................................................................................................................. 9

1.1 Scope of Specification ..................................................................................................................................9

1.2 Definitions and Abbreviations ................................................................................................................. 10

1.3 Applicable Codes and Standards ............................................................................................................ 12

1.4 Structural Classes ....................................................................................................................................... 15

1.5 Materials ...................................................................................................................................................... 16

2. WELDING .............................................................................................................................. 17

2.1 General ......................................................................................................................................................... 17

2.2 Definitions ................................................................................................................................................... 17

2.3 Weld Class ................................................................................................................................................... 18

2.4 Welding Processes ..................................................................................................................................... 18

2.5 Consumables ............................................................................................................................................... 20

2.6 Storage and Handling of Consumables ................................................................................................. 22

2.7 Documentation ........................................................................................................................................... 24

2.8 Welding Book ............................................................................................................................................. 25

3. WELDING PROCEDURES .................................................................................................... 27

3.1 General ......................................................................................................................................................... 27

3.2 Welding Procedure Specifications .......................................................................................................... 28






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3.3 Qualification of Welding Procedures ..................................................................................................... 29

3.4 Qualified Principal Positions .................................................................................................................... 30

3.5 Validity of Welding Procedures (essential variables) .......................................................................... 30

3.6 Testing .......................................................................................................................................................... 33

3.7 Special Test.................................................................................................................................................. 41

4. WELDERS AND WELDING OPERATORS ......................................................................... 46

4.1 General ......................................................................................................................................................... 46

4.2 Qualifications .............................................................................................................................................. 47

4.3 Retests .......................................................................................................................................................... 49

5. PRODUCTION WELDS ........................................................................................................ 50

5.1 General ......................................................................................................................................................... 50

5.2 Welding Sequences .................................................................................................................................... 53

5.3 Temperature ................................................................................................................................................ 53

5.4 Repairs .......................................................................................................................................................... 53

5.5 Closure Welds ............................................................................................................................................. 56

5.6 Stress Relieving Post Weld Heat Treatment ......................................................................................... 59

5.7 Welding Parameter Checking .................................................................................................................. 61

6. FABRICATION ...................................................................................................................... 62

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

6.2 Forming ........................................................................................................................................................ 62






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6.3 Welded Connections .................................................................................................................................. 64

6.4 Welded Attachments ................................................................................................................................. 68

6.5 Site Assembly .............................................................................................................................................. 68

6.6 Manufactured And Miscellaneous Items ............................................................................................... 69

6.7 Finishing of Surfaces ................................................................................................................................. 69

6.8 Rat Holes ..................................................................................................................................................... 70

6.9 Bolted Connections .................................................................................................................................... 70

7. PREFABRICATED ITEMS TOLERANCES ........................................................................... 71

7.1 Fabricated Tubular Nodes and Cones .................................................................................................... 71

7.2 Rolled or Fabricated Beam ....................................................................................................................... 76

7.3 Stiffened Plate Panels ............................................................................................................................... 78

7.4 Other Fabrication Details .......................................................................................................................... 80

8. FINAL FABRICATION TOLERANCES ................................................................................ 82

8.1 Position of Nodes ...................................................................................................................................... 82

8.2 Deck Plans ................................................................................................................................................... 82

8.3 Handrails ...................................................................................................................................................... 84

8.4 Walkways, Landings and Stairways ........................................................................................................ 84

9. INSPECTION OF WELDMENTS ......................................................................................... 85

9.1 General ......................................................................................................................................................... 85

9.2 Definitions ................................................................................................................................................... 85






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9.3 Reference Standards .................................................................................................................................. 86

9.4 Methods of NDT ........................................................................................................................................ 86

9.5 Extent of NDT ............................................................................................................................................. 87

9.6 Edge Inspection .......................................................................................................................................... 88

9.7 Qualification of NDT Procedures ............................................................................................................ 88

9.8 Qualification of NDT Personnel .............................................................................................................. 90

9.9 Visual Inspection Execution ..................................................................................................................... 91

9.10 Radiographic Testing Execution .......................................................................................................... 91

9.11 Ultrasonic Testing Execution ................................................................................................................ 92

9.12 Magnetic Particle Inspection Execution ............................................................................................. 94

9.13 Standards of Acceptability ................................................................................................................... 96

9.14 Reports ..................................................................................................................................................... 99

10. TESTING OF FIELD INSTALLED COMPONENTS .......................................................... 101

10.1 Preassembly Testing ............................................................................................................................ 101

10.2 Hydraulic and Pneumatic Testing ..................................................................................................... 101

10.3 Testing of Packers System.................................................................................................................. 102






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1. GENERAL

The Hengam Field is located in the Persian Gulf at approximately 45 km south of Qeshm Island. Iranian

Offshore Oil Company (IOOC) has awarded HENGAM offshore development EPCI project to Intelligent

Solutions Inc. and Ocean development LLC. Joint Venture to perform Basic & Detailed Engineering, as

well as procurement, fabrication, installation, pre-commissioning & commissioning for:

Topside facilities of three offshore wellhead platforms

Infield pipe lines

Submarine composite Cable (Power, Control, Fiber optic) from offshore to onshore facilities.

1.1 Scope of Specification

This specification covers the minimum requirements for fabrication and construction of WHP

Topside decks of the Hengam Offshore Development Project..

This specification contains general requirements: construction drawings shall prevail over this

specification.

As such, the contents of this specification define the minimum requirements for the fabrication but does

not cover the inspector’s activity during phases of qualification, fabrication and testing such activity

procedure shall be produced during detail design and fabrication stage.

The detailed specification shall be subject to approval by the Company.

The following topics shall be addressed:

i. Definition of structural classes.

ii. Handling, control, quarantine and storage of materials, including receipt.

iii. Inspection, conformity with specification and unidentified materials.

iv. Gases for gas shielded processes.

v. Requirements for welding procedure qualifications including essential variables.

vi. Preparation and fit-up joint.

vii. Drawings and fabrication documents.

viii. Ring stiffeners, cones and splices where applicable.

ix. Rat holes.

x. Fabrication of nodes where applicable.

xi. Local fabrication tolerances, circumference, ovality, out-of-straightness, mismatch etc.

xii. Girders, plate sections.

xiii. Fabrication tolerances (global).

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xiv. Decks and modules.

xv. Piles.

xvi. Conductors, J tubes and risers.

xvii. Handrails, landings, floor plate and secondary steel.

xviii. Extent of non-destructive testing.

xix. Attachment of anodes.

xx. Testing of grouting systems.

xxi. Bolted connections.

xxii. Sketches:

Location of test specimens for plate PQR.

Location of test specimens for tubular PQR.

Location of test specimens for T-butt PQR.

PQR for welded joints - location of impact specimens.

Weld toe grinding.

Beam splices allowed zones.

Tolerances on ring stiffeners.

Web stiffeners.

Measuring centre line and best fit line definition.

Tolerances on legs and piles.

Tolerances on shear plate.

xxiii. Temporary work erection sequences and calculations for elements greater than 100 tonnes.

xxiv. Fabrication documents.

1.2 Definitions and Abbreviations

Project HENGAM offshore development EPCI project

Company Iranian Offshore Oil Company (IOOC)

EPCI Contractor means Company mentioned in the Contract as part of the "other part"

and includes its successors and permitted assignees. (ISI/ODCO)

Contract means the “Contract” made between the “Company” and the

“Contractor” and comprises the documents stated in the Agreement to

form the “Contract”.

Work means the work and other obligations to be performed by “Contractor”

as described in the “Contract”.






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Vendor means anyone who provides goods or services to the “Company”. A

vendor often manufactures and/or sells their products to a customer.

Shall / Is to be indicates a mandatory requirement.

Should indicates recommended.

May indicates a freedom of choice.

Fabrication Drawings means drawings by Contractor that contain all the necessary

information required to fabricate items at shop and yard level.

Assembly sequence drawings and temporary support drawings are

considered fabrication drawings

As-built Drawings means fabrication drawings, issued by Contractor, on which are

reported all the information on how the construction has been actually

built. Assembly sequence drawings and temporary support drawings

need no to be issued in “as-built” version, except that all attachments

left onto the structure shall be reported on as-built drawings.

Fabrication means built-up of single items, generally executed in a shop.

na not applicable

nr not required

Re minimum specified yield strength

Rm tensile strength

t thickness

NDT Non Destructive Test

Parent Plate rolling unit, also mother plate

Material Grade level of yield strength

Material Quality additional measured mechanical characteristics such as Charpy-V,

through thickness properties (Z), guaranteed mechanical

characteristics after stress relieving heat treatment (R)

Closure Weld weld on tubular with inside diameter of 600 mm or greater without back

gouging; generally they are welds made on diagonal tubular after row

roll-up

Insert rolling unit, also mother plate






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1.3 Applicable Codes and Standards

For items not specially covered by this specification, the latest editions of the following codes and

standards in the order shown below shall be used:

AWS Structural Welding Code D1.1

API RP 2A Recommended Practice for Planning, Designing and Constructing Fixed Offshore

Platforms – Working Stress Deign

API RP 2X “Recommended Practice for Ultrasonic Examination of Offshore Structural

Fabrication and Guidelines for Qualification of Ultrasonic Technicians”, Standard

1104 NDT (Para. 9

API 2B API Specification for Fabricated Structural Steel Pipe

API 2H API Specification for Carbon Manganese Steel Plate for Offshore platform Tubular

Joints

API 5L API Specification for Line Pipe

API 2W Specification for Steel Plates for Offshore Structures Produced by Thermo

Mechanical Control Processing

API 2Y Specification for Steel Plates, Quenched and Tempered for Offshore Structures

AISC Structural Welding Code-Steel

AWS B1.11 Guide for the Visual Inspection of Welds

AWS A5.5 pecification for Low Alloy Steel Covered Arc Welding Electrodes

AWS A5.12 Specification for Tungsten Arc Welding Electrodes

AWS A5.17 Specification for Carbon Steel Electrodes and Fluxes for Submerged Arc Welding

AWS A5.18 Specification for Carbon Steel Filler Metals for Gas Shielded Arc Welding

AWS A5.20 Carbon Steel Electrodes for Flux Cored Arc Welding

AWS A5.23 Specification for Low Alloy Steel Electrodes and Fluxes for Submerged Arc

Welding

EEMUA 158 Construction specification for fixed offshore structures

IACS Consumable Classification from Institutes members of the IACS International

Association Classification

EN 288 Specification and approval of welding procedures for metallic material (Para. 3)

BSI 709 “Methods of destructive testing fusion welded pressure vessel” welding

procedures (Para. 3)

BSI 5500 “Specification for unfired fusion welded pressure vessel” local out roundness

(Para. 7)

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EN 287 Approval testing of welders-Fusion welding – Part 1 (Para. 5)

EN 10025 “Hot rolled products of non-alloy structural steels and their technical delivery

conditions” production weld (Para. 5)

EN 10002 Metallic materials-Tensile Testing-Part 1

EN 10045 “Charpy impact test on metallic materials”, Charpy-V Specimen (Para. 3)

EN 10204 Types of Inspection document

BS 3692 Specification for ISO metric precision hexagon bolts, screws and nuts.

BS 3643 ISO metric screw threads, Part 1 'Thread data and standard Thread series'

BS 4190 Specification for ISO metric black hexagon bolts, screws and nuts

BS 729 Hot Dipped galvanized coatings on iron and steel articles.

BS EN 462 Non-Destructive testing image quality and radiographs Part 1-5

EN 970 Non-Destructive Examination of fusion weld

EN ISO 9934-1 Non-Destructive Testing – Magnetic particle

ASNT-TC1A Recommended Practice, Personnel Qualification and Certification in

Non-Destructive Testing

ASTM A6 General Requirements for Rolled Steel Plates, Shapes, Sheet Piling, and Bars for

Structural Use.

ASTM A36 Structural Steel

ASTM A53 Pipe, Steel, Black and Hot-Dipped, Zinc-Coated Welded and Seamless

ASTM A106 Seamless Carbon Steel Pipe for High-Temperature Service

ASTM A120 Pipe, Steel, Black and Hot Dipped Zinc-Coated (Galvanized) Welded and

Seamless, for Ordinary Uses

ASTM A123 Zinc (Hot-Galvanized) Coatings on Iron and Steel Products

ASTM A307 Carbon Steel Externally Threaded Standard Fasteners

ASTM A325 High Strength Bolts for Structural Steel Joints

ASTM A370 Mechanical Testing of Steel Products

ASTM A500 Cold Formed Welded and Seamless Carbon Steel Structural Tubing in Rounds

and Shapes

ASTM A563 Carbon and Alloy Steel Nuts

ASTM A572 High-Strength Low Alloy Columbium-Vanadium Steels of Structural Quality

ASTM B695 Coatings of Zinc Mechanically Deposited on Iron and Steel

ASTM F436 Hardened Steel Washers for Use with High Strength Bolts

ASTM A490 Specification for quenched and tempered alloy steel bolts for structural steel

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joints.

ASTM A578 Specification for straight beam ultrasonic examination of plain and clad steel

plates for special applications

ASTM 633 Specification for normalized high strength low alloy structural Steel.

ASTM A193 Alloy steel nuts for bolts for high pressure and high Temperature Service

ASTM A320 Standard Specification for Alloys-Steel bolting Materials for Low Temperature

Service

ASTM F568 Specification for Carbon and Alloy Steel Externally Threaded Metric Fasteners

SA 435/435M Specification for straight beam ultrasonic examination of steel plates.

ANSI B1.1 United Screw Threads (UN & UNR Thread Form)

ANSI B18.22 Square and Hex Nuts

ANSI B 18.22.1 Lock Washers

Materials which shall be certified by Certifying Authority shall be in accordance with the relevant codes

of the Certifying Authority.

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1.4 Structural Classes

For the scope of this document the structural elements of the offshore installations are subdivided in

classes. Their definition is as follows:

Structural

Classes

Definition Topside Decks

a Structural elements essential for the safety

of the platform with low structural

redundancy, complex shape and stresses

concentration not easily foreseeable

Not typical nodes with complex geometry

b Structural elements essential for the global

safety of the platform

Typical nodes with simple geometry; Lifting

padeyes and their connection to the deck;

Legs; Tubular and beam elements situated

between two legs; Main girder; Main deck

node & connection; Cans; Crane pedestal;

Flare and bridge supports

c Essential structural elements for the total

structure safety with simple geometry and

with fatigue stress not dimensioning

Beams with height higher or equal to 300mm

or thickness higher than 15mm; Primary

columns and braces; Structural wall; Bridge

structure and flare; Crane boom rest; rotating

equipment support beam; stiffener at node on

primary beam (thicker than 15mm)

d Significant structural elements for the local

safety of the structure

Beams with height lower than 300mm and

thickness up to 15mm; secondary columns

and braces, floor plate and hatch cover for

strength member; sea fastening; equipment

support; Handling support & monorail;

stiffener of secondary structure

e Unimportant structural elements and non-

structural elements

Checkered plates; Stairs and walkway, Not

structural walls; Draining system; Ladder;

Handrail; Grating; Access & service; floor

plate and hatch cover for non-strength

member; Pipe & handling supports

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This classification does not consider structural elements that are removed after platform installation, but

includes those items, although removed, they are fundamental (buoyancy tanks, lifting aids etc.).

Appendix-A shows typical decks structural elements relevant class. Construction drawings may indicate

specific information about structural element class. Ambiguous cases relevant to structural element

class shall be cleared by Company.

Structural elements which are removed from the platform after its installation are excluded from this

classification, (i.e. rigging platform, temporary stairs, etc.,). However, those which are removable but

essential for the successful installation of the structures, (i.e. bumpers, guides , lift.ng padeyes,etc.)

shall be included

1.5 Materials

All steels to be used shall comply with HEN-0000-ST-SP-0001, “Structural Steel Material Specification”.

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2. WELDING

2.1 General

All structural welding shall be in accordance with the requirements of this specification and latest of

AWS D1.1, and in case of any deficiency use of other standards shall be subjected of Company

approval.

Steel backing strips, out of closure welds, may be used upon Company’s approval only, and in

accordance with the section 3.7.4.

2.2 Definitions

The following definitions are used:

SMAW shielded metal arc welding (using manual equipment)

SAW submerged arc welding (using automatic equipment)

GTAW gas tungsten arc welding (using manual equipment)

GMAW gas metal arc welding

GSFCAW gas shielding flux cored arc welding

SSFCAW self shielding flux cored arc welding

WPS welding procedure specification

WPQR welding procedure qualification record

HAZ heat affected zone

WM weld metal

FL fusion line

KCV set in HAZ Charpy V test set, consisting of three (3) groups of three (3) specimens

each from the following lines: fusion line (FL=50% WM and 50% HAZ),

FL plus 2mm, FL plus 5mm, for a total of 9 specimens

KCV set in WM Charpy V test set, consisting of three (3) specimens in weld centerline

TM thermomechanically controlled rolled (base material):

thermomechanical rolling process carried out with a rigid control of both

plate temperature and rolling grade

Q&T quenched and tempered (base material)

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2.3 Weld Class

The welds to be executed are grouped in classes, corresponding to the structural element classes, of

which they maintain the same name.

Different requirements on applicable welding processes, mechanical characteristics, NDT type and

percentage, defects acceptability combinations are defined for each weld class.

In welded joints between elements of different structural classes the higher structural element class

shall govern.

2.4 Welding Processes

2.4.1 Acceptable Welding Processes

The approval is to be obtained prior the use of the process in production begins.

All welding fabrication of structures shall be accomplished with low hydrogen processes.

Welding processes for structural classes of components are listed in table 2.1.

Other welding processes could be employed under Company approval.

Table 2.1 – Joint Type and Weld Class

Structural Element Class = Weld Class

a b C d e

Butt

SAW

SMAW

GS/SSFCAW

SAW

1st run GS/SSFCAW GTAW SMAW

T butt

SAW

SMAW

GSFCAW

SAW

SMAW

GS/SSFCAW

SMAW

1st run GTAW SMAW

Fillet

SAW

SMAW

GSFCAW

SAW

SMAW

GS/SSFCAW

GMAW

GS/SSFCAW

Closure

Na

SMAW

GSFCAW SMAW

GS/SSFCAW

GMAW

1st run GTAW SMAW

Seal SMAW GS/SSFCAW GMAW






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The use of GTAW shall be limited to the first passes where second side is not accessible. GTAW shall

be utilized only with direct current, straight polarity.

First run on principal tubular longitudinal double side welds may be carried out by GMAW process

providing it is completed removed prior to back passes are executed.

The use of “narrow gap” welding processes is permitted only upon Company’s approval. In this case

full details about the process, the consumables, the NDT techniques, the relevant applications and the

previous experience are to be documented.

2.4.2 Restrictions of Welding Processes

The following procedures require the following positions:

SMAW all positions, except vertical down

SAW flat position in general, horizontal position for fillet weld only

GMAW flat position in general, horizontal position for fillet weld only and with

“spray arc” technique

GS/SSFCAW all positions (except the vertical down for class “e” structures only),

under Company’s approval only, after a documented experience is

furnished to Company’s satisfaction

Welding procedures shall not exceed the following limits:

SMAW for heat input exceeding 3 kJ/mm; bead width exceeding 16mm or

4 times the core wire diameter

SAW for heat input exceeding 3 kJ/mm

GTAW when adequate environmental shielding is not provided

GSFCAW for heat inputs exceeding 3 kJ/mm: when adequate environmental

shielding is not provided

SSFCAW shall not be used with heat inputs exceeding 1.5 kJ/mm or less than

0.6 kJ/mm.

shall not be used without the voltage and wire-feed speed set and

locked.

shall not be used in combination with SAW without special

prequalification tests supervised by the Company’s representative, and

shall only be used using the vertical down, stringer bead technique.

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ALL welding on materials less than 30mm thickness with a heat input

exceeding 3 kJ/mm; square edge butt welds greater than 8mm

thickness; welding on second side of a joint without back gouging

except for SAW procedures using the punch-through technique; single-

ass fillet welds (other than by submerged arc) with a leg length greater

than 7mm; use of ceramic inserts.

The following are permitted only with the Company’s approval:

The use of other welding processes.

The use of narrow gap welding.

The use of supplementary consumables (powder additions, hot wire additions etc).

The use of ceramic inserts.

The use of backing strips.

Single-pass fillet welds.

In such cases, full details about the process, the consumables, the NDT techniques, the intended

application and the Vendor’s previous experience in meeting the requirements of this specification with

the proposed process are to be documented. The approval is to be obtained prior to the submission of

the WPS.

2.5 Consumables

All consumables shall be subject to approval by the Company’s representative.

The use of consumables is subject to meeting the welding procedure qualification requirements.

Consumables to be used shall have chemical composition similar to and have a yield strength not lower

than the base material. The use of consumables with yield strength higher than 100MPa of base

material are not allowed.

Consumables to be used for welded joints between steels having different yield strength shall be those

applicable to the higher strength steel.

The use of filler metals giving a low diffusible hydrogen deposit (less than 5 cm3 per 100g of weld metal,

carried out with mercury measurement method, or humidity equal to 0.2% of the weld metal weight,

according to AWS D1.1.) is compulsory when one of the following conditions is fulfilled:

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Welds in classes “a, b, c”

Weld thickness greater than 10mm

Specified Minimum Yield Strength of one of the parts to be joined equal to or greater

than 275MPa

Electrodes in sealed boxed shall have the hydrogen level certified.

Electrodes classification shall conform to AWS. Electrodes classified conform to other specifications or

codes are accepted provided correspondence and in that case the WPQ has in the name an essential

variable All electrodes, according to the reference code or specification, shall be marked.

2.5.1 SMAW

Electrodes for SMAW shall conform to AWS specification A5.5 classification E7015-A1, or E7016-A1,

E7018-A1, E8016-C3, E8018-C3, and AWS A5.1 classification E7015, E7016, E7018 and E7028 (the

last one for fillet weld only).

2.5.2 SAW

Wires and fluxes for SAW shall conform to AWS specification A5.17 classification F7XX-EXXX or

F6XX-EXXX or AWS specification A5.23 classification F7XX-EXXX-Al or FSXX-EXXX-Al.

2.5.3 GTAW

Rods for GTAW shall conform to AWS specification A5.18 and electrodes shall conform to AWS

specification A5.12.

2.5.4 GMAW

GMAW consumables shall be in accordance with AWS specification A5.18 (classes ER 70S2, ER

70S3, ER 70S6, ER 70S7). Processes with 100% CO2 are not allowed; gas mixtures with 80% Ar and

20% C02 are acceptable.






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2.5.5 GSFCAW and SSFCAW

Consumables shall be in accordance with AWS specification A5.20 (classes E70nl-T6 E70nl-T8). Gas

mixture normally used is that with 80% Ar and 20% CO2, with consumables classes E70nl-Tl and E

70nl-T5. Other type of gas mixture may be applied after Company approval.

2.5.6 Gases

CO2 is to have a purity grade not lower than 99.8% and a dew point not higher than 45°C below zero.

Argon and Helium are to have a purity grade not lower than 99.99% and a dew point not higher than

45°C below zero.

Gases are to be supplied in bottles where type is to be clearly indicated. Fixed distribution networks

are to be clearly identified in their content. Heaters for CO2 are to be used.

2.6 Storage and Handling of Consumables

The Contractor shall obtain manufacturer’s test certificates of welding consumables used on the project.

The certificates shall include the following information:

Chemical composition

Tensile and charpy properties (if applicable)

Particle size distribution (if applicable)

All consumables shall be supplied in sealed moisture proof containers capable of maintaining the

consumables free from moisture for at least six months.

Unopened containers shall be stored in a dry location where the temperature shall not be less than

20°C and the relative humidity shall not exceed 50%.

Electrodes, fluxes and wires that have been contaminated by water, oil, grease, or all other deemed

unsuitable, or unmarked consumables shall not be employed in the work and shall be removed from the

worksites.

Company may require an additional monthly test (or two months in shop) and whenever he

considers that the consumable baking and maintaining procedure are applied in wrong way.

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On any electrode batch and on any flux lot, a moisture test in accordance with AWS specification A5.5,

may be carried out at Company's discretion. Samples shall be taken from ovens where electrodes and

fluxes are stored, ready for production use. The maximum moisture content by weight for low hydrogen

consumables shall be 0.2% for electrodes and 0.1% for fluxes.

Company reserves the right to verify the consumables chemical and mechanical characteristics by

destructive testing.

2.6.1 Electrodes

Low hydrogen electrodes shall be baked for 2 hours at 350/450°C, unless otherwise recommended by

the supplier. Thermocouple, which shall be previously calibrated shall be placed at midheight owen.

Initial drying may be omitted in case the electrodes are supplied in fully sealed packs with a

guaranteed hydrogen level content.

After withdrawing from ovens for use, electrodes shall be contained in heated portable quivers at a

temperature not lower than 70°C and shall be used within 4 hours. (manufacturer or supplier

recommendation shall be considered)

Electrodes not used within above time limit may be rebaked, provided they are in good conditions.

Redrying is generally acceptable to a maximum of 2 times.

Electrodes that shall not be immediately applied may be stored in ovens at a temperature not lower

than 100°C after baking.

In alternative electrodes characterized by a low hydrogen level maintainment after box opening may

be used. Those electrodes are commercially available in packages equal to a workday or half workday.

Anyway Company may require a test to verify the characteristical performance of those electrodes.

If these electrode types are used, those unemployed, at the day end, shall not be employed again.






HEN 0000 ST SP 0002 24 of 102

2.6.2 Fluxes

Low hydrogen fluxes storage, usage and rebaking requirements shall be as for electrodes.

The maximum amount of recycled flux used for welding shall not exceed 30% of the total (70%

minimum new flux). Fluxes may be recycled aspirating from welding and filtered to eliminate impurity

before mixing with new one.

The Contractor shall provide a handling and recycling procedure including details of baking, use of

heated hoppers, recovery system and circumstances in which flux is deemed unsuitable and scrapped.

2.6.3 Wires

Wires storage, usage and re baking shall be the same as for electrodes.

To avoid porosity, gas holes, hot cracking and low electrical contact, wires shall be free from grease

and moisture.

Current swing avoidance during welding shall be avoided through a regular coil speed.

At the workday end all the automatic welding coil winders shall be emptied as to avoid wire moisture

contamination.

2.7 Documentation

Prior to commencement of any part of the fabrication, the Contractor shall submit the following

documentation for approval by the Company:

Fabrication procedures, welding sequence and erection sequence;

Fabrication drawings including plate seam arrangement drawings and plate cutting drawings

with weld details;

Drawings and calculations of temporary works, inclusive of support points, jacking points and

sling points;

List of proposed welding consumables and Supplier;

Qualified welding procedures and repair welding procedures;

Certificates of welded and welding operators qualified;

Certificates of any fabricator supplied material;






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Key plans showing unambiguous member identification and weld making scheme;

Procedure for heat treatment of welds and their areas of applications;

Procedures for non-destructive testing and inspection and associated personnel qualification;

Cold Forming and straightening procedure;

Identification and control procedures for material;

Procedure for dimension control of tolerances during fabrication.

In accordance with the provisions given in following sections.

2.8 Welding Book

Before the beginning of the works, the Contractor shall prepare a welding book covering all the welding

operations to be performed. This book shall be permanently available to the Company on the site where

the welding is to be carried out.

It shall comprise:

Identification sketches or a list of welded joints per type

A summary of the accepted welding procedures with their qualifications

All welding procedure specifications which shall be applied

Destructive and non destructive testing, specifying the technique used for the latter

WPQ and WPS that shall be carried out during fabrication shall be added to be welding book.

For each welding procedure qualification shall be indicated:

the references(s) of the qualification certificate(s) specifying the range of thicknesses and

covered diameters together with maximum CEV qualified for steels with Re > 275MPa

the welding procedure qualification records, with the testing record certificates and inspection,

during fabrication, certificates of the base and filler metals

the chemical composition and the carbon equivalent CEV of the test pieces (for steels with a

minimum specified yield strength higher than or equal to 275MPa only)

For each welding procedure specification shall be indicated:






HEN 0000 ST SP 0002 26 of 102

base material grade (when the grade actually used is be different from that initially foreseen

on the drawings, this shall be indicated)

the joint configuration before and after welding (size and tolerance); passes number; if a

temporary or permanent backing is used; the grade of the backing material, the precision of the

backing fit, the method of removal (if foreseen)

conditions and special measurements, e.g. preheating and post heating temperature

(soaking time), maximum interpass temperature

if stress relieving treatment is foreseen: the procedure, the temperature, the hold time, the

heating and cooling rates, and the tolerances for each of these parameters

For each pass the following indications shall be given:

the welding process specifying, if necessary, whether it is a manual, a semiautomatic or

an automatic process

the welding position

the consumables used (standard name, trade name, diameter)

welding parameters with tolerances (voltage, speed of travel, current, heat input, flow rate

and type of gas)

welding technique detailing polarity and nature of current; welding direction; type of

protection (gas); weave bead or stringer bead; whether or not back welding is carried out

after gouging and/or grinding






HEN 0000 ST SP 0002 27 of 102

3. WELDING PROCEDURES

3.1 General

Welding of weld classes "a, b, c" shall be carried out in accordance with approved and qualified welding

procedures only.

All welding procedures applied shall be qualified unless Contractor procedures have already been

qualified.

Welding of weld class "d" may be executed with procedure previously qualified by Contractor, without

the need of new qualification.

Welding of weld class "e" may be carried out without qualified processes.

Prior to beginning work, the Contractor shall qualify all the required welding procedures for the various

materials and welded seams of the structures to be fabricated.

The information indicated on each WPS shall be consistent and shall not leave the welder to choose

within different combinations of parameters.

3.1.1 Preheating and Interpass

Tacking and welding shall be carried out with preheating temperatures ranges stated in table 3.1.

Carbon Equivalent formula is (llW):

CEV = C+ Mn/6 + (Mo + Cr + V)/5 + (Ni + Cu)/15

Table 3.1 – Minimum Preheating Temperature

CEV

Weld Thickness

≤ 20mm ≤ 30mm > 30mm

≥ 0.39 20 20 50 (20)

≥ 0.41 20 20 75 (50)

≥ 0.43 20 50 (20) 100 (75)

≥ 0.45 50 (20) 100 (75) 125 (100)

Note: values in brackets refer to SAW only.






HEN 0000 ST SP 0002 28 of 102

Arc air gouging and oxicutting may be carried out without preheating.

Preheating temperature is to be measured on bevels and at 50mm minimum from bevels at both sides.

Working interpass temperature shall not be lower than preheating one, nor higher than 250"C.

Preheating and interpass values differing from the above stated may be used provided measured

during the execution of welding procedure qualification.

3.1.2 Heat Input

Welding heat input shall be calculated with one of the following formulas:

HI= 0.6VA/ s

HI= 0.001 VAT / (ROL)

where: HI= heat input in J/m; V =arc voltage in Volts; A= arc current in Ampere;

s = welding speed in em/min; T = arc time in second;

ROL = electrode run-out-length in mm.

Heat input value for filling passes and for any process on TM steel may be higher than those

considered in the section 2.4.2, provided adequate welding procedure qualification demonstrates it is

not detrimental to the mechanical characteristics of welded joint.

3.2 Welding Procedure Specifications

Welding procedure specifications (WPS) shall specify the EN 288 requirements in addition to the

following information (as recorded on relevant Procedure Qualification Record):

company name and unique WPS number

welding process, or processes when more than one is used in making a complete joint;

steel type, and whether it is normalised or TM, thickness, length, width and pipe diameter (when

applicable) used for procedure qualification;

sketch of joint showing plate edge preparation (specifying if oxygen cutting or machining) and joint

fit-up tolerances;

thickness and diameter ranges qualified;






HEN 0000 ST SP 0002 29 of 102

welding position and welding direction (for vertica1 position);

the make, trade name, classification and size of welding consumable and fluxes.

Any pretreatment of electrode/consumable;

name, type and flow rate for gas shielding, and backing if applicable;

sketch showing number of beads, welding sequence and relevant consumables and welding

parameters for each joint zone;

for each run: the current type, polarity, arc current and voltage, welding speed, or electrode run-

out length and relevant burning time;

treatment to second side;

actual preheat and maximum interpass temperature used in the qualification test weld, and

those to be used in production; method of temperature measurement;

for semi-automatic processes: torch position, wire protrusion, frequency and waving amplitude;

post weld heat treatments (for avoiding hydrogen cracking and for stress relieving)

if applicable;

any deposition augmentation system used;

tack welding procedure;

Removal methods for weld defects.

3.3 Qualification of Welding Procedures

Qualification of welding procedures shall comply with AWS D1.1, EN 288, and RINA and as specified in

the following.

The welding procedures shall be certified by an Approved Body accepted by the Company.

Prequalified joints foreseen by AWS Dl.1 apply only to weld class "e".

The qualification of the welding procedures performed may be used for any other workshop or worksite.

The execution of procedure qualifications for SAW shall be done using the maximum value of the

allowable recycled flux percentage (Section 2.6.2).

Where tack welds in production will remain in final joint and are done by a different process to that used

for weld body, the procedure test plate shall be similarly tack welded and one macro section taken

through a tack location.






HEN 0000 ST SP 0002 30 of 102

3.4 Qualified Principal Positions

Qualified principal positions shall be in accordance with table 4.1 of AWS D1.1.

3.5 Validity of Welding Procedures (essential variables)

A qualified welding procedure is to be used within the limitation of essential variables as stated below.

The changes described below are to be considered essential and are to initiate a new procedure

qualification test.

When a combination of welding processes is used, the essential variables applicable to each process

shall be applied.

WPQ carried out on base material of quality not "Z" may be applied to other similar steels, including

quality "Z" or lower grade.

3.5.1 Material

Base Material: change of grade of steel, change of steel quality. Increase in product CEV above

0.02% (for Re > 300MPa only), and Pcm above 0.01% of maximum nominal value of steel in

comparison with the value of WPS. Change in manufacturing route. The qualification obtained for a

normalized materials is accepted also for TM materials, and not vice versa.

Groove preparation: presence of bevels protective coat. Oxycutting without grinding to sound metal.

3.5.2 Weld Geometry and Position

Groove angle: change of included angle greater than +10° or -5°.

Components angle: where acute angles in the stub to node can welds are below 45° weld processes

are to be qualified by the test of TKY joints. The bevel angle in this test is to be the smallest used in

fabrication.

Root face and root gap: changes of root face and root gap shall be in accordance with AWS D1.1,

either for double side weldings and for single side weldings.






HEN 0000 ST SP 0002 31 of 102

Groove design: change from double side welding to single side welding and vice versa; change in

groove weld preparation shape (V groove, U groove, etc. except that a single half V bevel qualifies a

single V, K qualifies X, and 2:1 and 1:1 preparations qualify each other and all intermediate

geometries).

Thickness: outside the qualified range listed in EN 288-3.

Misalignment: values exceeding the, lesser of 5mm or 10%t on double sided joints, 3mm or 10%t on

single sided joints. Misalignment of 2mm is permitted, regardless of other parameters.

Diameter: outside the qualified range listed in EN 288-3.

Welding Positions: outside the qualified range listed in Table 5.4 of AWS D1.1..

3.5.3 Consumables and Equipment

Welding consumables: change of electrode trade name; electrode and wire type are considered

equivalent on condition that they belong to the same certification class and are approved by a

Certifying Authority, in that case they do not have to be requalified.

Power: changes are made to pulsed power welding parameters.

Welding parameters: change from AC to DC or vice versa; change in DC polarity.

3.5.4 Procedures

Welding process: any change in welding process.

Preheating/working temperature: for preheating the lower limit of approval is the nominal preheat

temperature applied at the start of the welding procedure test, with a tolerance of -10°C/+50°C. For

interpass the upper limit of approval is the nominal interpass temperature reached in the welding

procedure test.

Post weld heat treatment: added or omitted; change beyond specified temperature range; soaking

time increased more than 25%; increasing or decreasing speed more than 20%.






HEN 0000 ST SP 0002 32 of 102

Gas shielding: gas type change from active to inert and vice versa; change of 10% or beyond in gas

composition; change +27% or -10% in flow rate.

Grinding: if grinding between passes is omitted.

Back-gouging: each reduction in depth of back-gouging in comparison with the qualified one for

automatic process; each increase higher than 10mm of qualified depth.

Back welding: if omitted.

Welding direction: change from uphill to downhill, and vice versa.

3.5.5 Welding Parameters

Voltage and current: change beyond 10% of mean values.

Bead: if each bead width increase, for any electrode diameter.

Speed: if wire feed speed setting for any pass is changed by more than 5%.

Heat input: change beyond 10% (tolerance applies to mean heats input values measured during

qualification in root, fill and weld cap passes) for weld class "a" and nodes of class "b". Welding of all

other elements of class "b" and of every other class is considered a change beyond 20%. Where heat

inputs in two positions are different, qualification in both positions qualifies all intermediate heat inputs.

3.5.6 Specific for SMAW

Measured current for any electrode diameter is changed by more than 20%.

Run out length for any electrode size is changed by more than 10%; where the runs out lengths in two

positions are different, qualification in both positions qualifies all intermediate run out lengths.

Core diameter of an electrode used for capping passes is reduced. All passes in the cap of the

qualifying weld shall use the same electrode diameter.






HEN 0000 ST SP 0002 33 of 102

3.5.7 Specific for SAW

Number of wires used for any pass is changed.

Separation of tandem arcs, transverse or longitudinal, is changed by more than 10%.

Feeding direction is changed by more than 5° transverse or 3° longitudinal to the weld.

3.5.8 Specific for GTAW

Root gap exceeding 3mm is to be qualified with separate procedure.

Tungsten wire changing diameter.

3.5.9 Specific for FCAW (GS and SS)

If the mean voltage for any pass deposited by other automatic or semi-automatic process is changed

by more than 10%.

Change of contact tip-to-workpiece distance.

3.6 Testing

The qualification of welding procedures is based upon visual examination, non destructive testing and

mechanical testing on test samples. Type and number of tests are those specified in Table 7 of RINA

“Rules For Classification for Fixed Offshore Platform” effective from 1st January 2004..

If different welding consumables or welding processes are applied for the same joint, impact tests

required are to be carried out for the related regions of the weld. If SAW tandem process is used and

fills passes have width over 19mm one KCV set is required at depth of 8mm.

Size and shape of specimens and test execution for Charpy-V are to comply with EU10045.

3.6.1 Test Coupon

The test plates used for procedure qualification (samples location) shall have the rolling direction

parallel to the test weld.






HEN 0000 ST SP 0002 34 of 102

CEV shall be not less than 0.02% and Pcm than 0.01% in comparison with the maximum of the

specification of the steel to be welded.

For Z quality material beams, samples taken for WPQ shall have welding direction parallel to the

rolling direction; for materials of other quality the welding direction can be perpendicular to the rolling

direction. (fig. 3.1)

Figure 3.1 – Beam Weld, WPQ Test Sample

Test conditions shall be a realistic simulation of the actual conditions that will be experienced.

When PWHT of nodes or other sub-assemblies is required, all relevant procedures qualifications shall

include PWHT over the full range of material thickness.

The dimensions of the test plates (coupons) shall be in accordance with EN 288-3, paragraph 6.

When plate thickness to be tested is over 36mm or the power of tensile testing machine is not

sufficient, tensile specimens may be cut into a number of approximately equal strips not exceeding

36mm (or the machine strength equivalent thickness whichever is the greater) with a minimum overlap

of 2mm. Test shall be performed on each strip and the results averaged.






HEN 0000 ST SP 0002 35 of 102

3.6.2 Acceptance Criteria

The welding procedure is qualified when the soundness and mechanical properties comply with the

requirements hereafter indicated:

Non-destructive tests:

Welded joints soundness is to comply with the prescriptions of Section 9.13. Any PWHT, when

required, and following NDT shall be carried out not prior than 48 hours from weld completion. Repairs

are not allowed.

The locations of all imperfections exceeding 50% of the reference level shall be marked, and the

cutting of tests pieces shall be arranged to avoid these imperfect regions.

Destructive tests:

Transverse tensile tests: the tensile strength of the welded joint is to be in accordance with EN 288-3

paragraph 7.4.1; in case of welding between steels of different grades the tensile strength shall be

equal to the lower steel grade.

All weld metal tensile test: specimens shall be taken out from full weld metal, and shall take the form

of the "reduced transverse test" piece to BS 709; the tensile strength of the welded joint is to be at

least equal to the minimum specified tensile strength.

Bend tests: test conditions and acceptability limits shall be in accordance with EN 288-3 paragraph

7.4.2; bending angle test shall be of 180°.

Toughness tests: the average and minimum Charpy V-notch energy absorption recorded at each

specified position in WM and HAZ is to comply with the requirements in the Project specification –

Structural Steel Material Specification, HEN-0000-ST-SP-0001:






HEN 0000 ST SP 0002 36 of 102

Impact Test Energy (Joule)

ZTA ZF MB

Designation Test

Temperature

Average

Energy

Test

Temperature

Average

Energy

Test

Temperature

Average

Energy

Pr EN 10113 S355 NL

Pr EN 10113 S275 NL

31(Long,a -40)

20(trans,a -40 -40

22

14 -40 31 Var.

Pr EN 10113 S355 N

Pr EN 10113 S275 N

40(Long,a -20)

20(trans,a -20 -20

28

14 -20 40 Var.

EN 10025 S355 J2 27 -20 20 -20 27 -20

EN 10025 S355 JO

EN 10025 S275 JO 27 0 20 0 27 0

Note: Minimum values obtain by a single specimen must be greater than 70% of the average value

required.

Table 3.2 – Impact Test Set Location

Thickness Location Double Side Welding

t ≤ 45mm cap WM + HAZ

root WM + HAZ

t > 45mm cap WM + HAZ

root WM + HAZ

Note: Cap: 2mm +/- 0.5mm below external weld cap surface.

Root: in root region of back welding.

WM: weld metal in the center of weld.

HAZ: heat affected zone.

HAZ means: FL, FL+2mm, FL+5mm.

Macro section: EN 288-3 paragraph 7.4.3, test condition and acceptability shall be applied.

Hardness: the maximum hardness in any part across the welded joint shall not exceed 350 HV5.

3.6.3 Charpy-V Requirements

The Charpy-V requirement for specimens taken from WM and HAZ are shown in fig. 3.2, fig. 3.3, fig.

3.4 and fig. 3.5.

B4






HEN 0000 ST SP 0002 37 of 102

Figure 3.2 – Plate Butt Weld, Charpy-V Sets for t≤45






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Figure 3.3 – Plate Butt Weld, Charpy-V Sets for t >45






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Figure 3.4 – T joints, Charpy-V Sets for t≤45






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Figure 3.5 – Plate Butt Weld, Charpy-V Sets for t >45






HEN 0000 ST SP 0002 41 of 102

3.6.4 Retesting

Retesting shall be in accordance with EN 288-3, paragraph 7.5 with the following amendements.

Tensile: when the failure, on one or both the specimen, occurs for a load value that is less than 95%

of the tensile strength, the procedure will be rejected. When the failure, on one or both the specimen,

occurs for a load value that is between 95% and 100% of the tensile strength, two additional tests will

be carried out for the interested specimen.

Bends: two other specimens of similar type (face, root or side), located as near as possible to the

failed specimen, shall meet specification.

Macro and hardness: the surveys on two more sections of the coupon have to meet specification.

Toughness: in case one specimen tested gives an energy value below the specified minimum single,

or more than one value is lower than the minimum average, one further set shall be tested from the

same location. The new set shall meet the specified minimum values and conditions, and in addition

the mean value of all the two tested sets (the new and the failed) shall attain the specified minimum

average value. In case of any additional failure the welding procedure shall be rejected.

3.7 Special Test

3.7.1 TKY Joints

The joint qualification shall be carried out in accordance with EN 288-3 paragraph 6.2.4. The can shall

be positioned with vertical axis and brace acute angle downward (fig. 3.6).

Welding shall be carried out with a qualified T-butt procedure, or with a qualified butt weld procedure.

In this case the required mechanicals to qualify the T-butt procedure shall be carried out.

Testing shall be 100% NDT, WM and HAZ toughness at 12 and 3 o'clock positions, macro and

hardness's at 12, 3 and 6 o'clock positions. Acceptability shall be in accordance with applicable

requirements of this specification.






HEN 0000 ST SP 0002 42 of 102

Figure 3.6 – Special Test for TKY joints

3.7.2 Welding Repair

Special qualification for repair of excavated welds is required in case the repair process differs from

the filling used.

The qualification shall be carried out in the worse position, through the utilisation of parameteres which

are worse than the expected ones.






HEN 0000 ST SP 0002 43 of 102

HAZ of both parent material and original weld shall be tested.

The Contractor shall issue standard WPQ repair that may be applied in various cases, including the

applied methodology, length and maximum excavation depth, cleaning and NDT methods, preheat

temperature and weld re shaping, if any. The previous methodology shall be exactly applied.

3.7.3 Buttering

Buttering procedure carried out with the same process and parameters as for the filling weld need not

to be qualified.

In case buttering is done with a different welding process, or with same process but different

parameters, from main weld, the buttered area and HAZ shall be tested as for a different process weld.

Both HAZ on base material induced by buttering and HAZ on buttered area induced by main weld shall

be KCV tested. In case one KCV set position coincides with another KCV set, one may be superseded.

Welding procedure shall be carried out with maximum allowed root gap conditions.

Buttering thickness shall be 6mm and 5mm width on each bevel; buttering shall apply only to

weldments having thickness 15mm and above. Buttering area shall be MT inspected.

3.7.4 Permanent Backing Strip Welds

Contractor may apply this technique providing a special WPQ including the insertion of steel backing

strip into the fit-up joint and its tightening against bevel root, first passes, filling passes and relevant

NDT execution.

This procedure is not applied in stub-can joints.

The test is carried out by welding 1a joint, at scale 1:1, built up by two tubular pieces with diameter

equal to the minus on which the process is intended to be applied (fig.3.7). A macro graphic

examination shall be executed on the weld root.






HEN 0000 ST SP 0002 44 of 102

Figure 3.7 – Permanent Backing Strip Weld

Tacking shall be carried out inside the bevel all over the weld root: tacking shall never be done outside

bevel.

Air gap between the bevel root and backing strip shall be the minimum, before root welding starts.






HEN 0000 ST SP 0002 45 of 102

A special UT procedure shall be defined and applied to verify the bevel fusion, the absence of tacking

between base material and backing strip, and to recognize the root discontinuity caused by backing

strip. The actual bevel inclination shall be considered for choosing UT probes. The procedure shall

include the execution of an identification mark on base material at 100mm from joint, to verify the root

gap dimensions and the centre of backing strip in every point before weld execution.

"Backing strip" welds shall be indicated on "as-built" drawings. Maximum root gap variation shall not

exceed 6mm. Backing strip weld is allowed with root gap values higher than 12mm but not exceeding

20mm.

Overall procedure produced by Contractor shall be approved by the Company before its application.

3.7.5 Grout Beads

Mechanical tests required on grout weld beads shall be two macros, with hardness survey on fusion

line and HAZ under bead, one KCV set in HAZ and WM as shown in figure 3.8.

Figure 3.8 – Charpy-V Set Grout Bead

KCV temperature test shall be equal to the test temperature utilised for the parent material and shall

conform with the minimum energy requirements for this last one.






HEN 0000 ST SP 0002 46 of 102

4. WELDERS AND WELDING OPERATORS

4.1 General

All welding on the structures shall be performed by welders or operators qualified by an Approved Body

accepted by the Company.

All qualified welder shall have a certification that witnesses the qualification. The certification shall be in

accordance with EN 287 code.

The purpose of welder performance tests is to verify that the welders may produce welds in accordance

with these specification requirements using a qualified welding procedure.

Welder qualification tests shall be carried out to an approved welding procedure specification. Welders

having successfully performed the welds of qualification tests of a qualified process are automatically

qualified for the same procedure.

All welders shall be qualified with at least one of the qualification tests indicated in Table 7 of EN 287-1

1992 "Approval testing of welders - Fusion welding – Part 1: Steels".

All welds using SMAW process are to be conducted with low hydrogen electrodes. At least one

stop/start has to be produced in each run.

The welders are generally to be qualified for all positions butt welding. For welding occurring only in one

or limited number of positions, performance test may, after agreement with Company, be performed

only in this (these) position(s). Welders, to be qualified for GSFCAW/SSFCAW or GMAW fillet, are to be

qualified in all positions

The welder can be qualified for mixed welding process by only one test, or by two tests as for EN 287-1

ch. 6.2.

Semi killed or fully killed C-Mn steels are normally to be used for welder qualification tests.






HEN 0000 ST SP 0002 47 of 102

4.1.1 Certification Validity

The certification validity shall be submitted to the Company approval when fabrication starts, and it

shall be in accordance with EN 287-1 with the following amendements.

A welder or welding operator may be required to be re-qualified if inspection during fabrication reveals

that extensive repairs are due to poor performance. This shall be done following a period of

supervised retraining. The length of this period shall be at Company discretion but shall be not less

than one week. The Contractor shall record details of retraining.

Company may review existing welder qualification meeting the requirements of this specification:

existing qualifications may be accepted at his solely discretion.

4.1.2 Categories of Qualification and Test Requirement

The fundamental categories that the Company will recognize are listed in the following paragraphs of

this section.

The coupons to be welded are indicated in the same paragraphs. The coupons shall be checked in

accordance with Table 8 of EN 287-1. NDT acceptability shall be as per more stringent requirements

of this specification.

Requalification is necessary if a different welding AWS classification consumable is used. It shall be in

compliance with EN 287-1 paragraph 6.5.

4.2 Qualifications

All the qualifications listed in EN 287-1 page 11, paragraph 6.3, will be applied. The extensions of the

welder’s qualifications shall be in compliance with Table 3 of EN 287-1.

4.2.1 Automatic Welding

Welding operators using the submerged automatic arc welding (SAW) process shall be qualified as

per AWS D1.1 Section 4 Part C and shall mark their welds for identification purposes.

Qualification with more than one wire qualifies one wire weld according to AWS D1.1 code.






HEN 0000 ST SP 0002 48 of 102

4.2.2 Manual Double-Side Welding

WPQ test welds shall be carried out in accordance with EN 287-1, Table 7.

4.2.3 Manual Single-Side Welding

WPQ test welds shall be carried out in accordance with EN 287-1, Table 7.

4.2.4 Closure Butt Welds

This qualification is required for all welders using the closure butt weld procedure. The qualification

requirements are the same as per manual single side welding, except that the root gap value shall be

as per relevant WPQ.

The strong-backs shall be sufficiently strong so that the gap between bevels does not reduce

significantly during welding.

The extension of the qualification is ruled by EN 287-1, Table 3.

4.2.5 Fillet Welds

Fillet welder qualification shall be carried out according to EN 287.

The extension of the qualification is ruled by EN 287-1, Table 3.

4.2.6 Carbon Arc-air Gougers

Carbon arc-air gougers, for structural class "a, b", shall demonstrate their ability to remove metal to a

uniform depth in a workmanlike manner.

A register of approved arc-air gougers shall be provided and up-dated on a monthly basis. If all

manual welders are qualified as gougers, no list is required.

4.2.7 Tackers

Tackers, for structural class "a, b", shall be qualified as per AWS D1.1 Part C Section 4.31 unless

already qualified for manual welding.






HEN 0000 ST SP 0002 49 of 102

4.3 Retests

Retest applicability requirements shall be in accordance with EN 287-1 paragraph 9 requirements.

Welders failing tests shall follow a congruous training period before retest. Such a training must be

proved by documents.






HEN 0000 ST SP 0002 50 of 102

5. PRODUCTION WELDS

5.1 General

5.1.1 Technique

The width of individual deposited weld beads in flat, horizontal and overhead position, with GMAW and

SMAW process, shall not exceed three times the electrode wire diameter or 16mm, whichever is the

less. In vertical position the width shall not exceed 15mm. For SAW tandem process only fill beads

may be 24mm. Vertical down welding is an acceptable technique only for GSFCAW and SSFCAW

process, for weld class "e".

Run-out tabs are recommended to have a length greater than 150mm, depending if single wire or twin

wire technique is used. Such tabs shall be positioned on both sides of each longitudinal weld. The arc

shall only be struck on the bevel faces only and not on base material.

Each run of weld metal shall be thoroughly cleaned from flux, spatter and all slag removed, by brush,

prior to deposit the next run. For double side butt weld the second side shall be cleaned to sound

metal prior to deposit the second side runs.

Should carbon arc air gouging be used, carbon and other residual debris shall be completely removed

by grinding or other approved mechanical methods.

The welding procedure for a single side butt weld shall provide 100% fusion of the root and be such

that distortion or contraction of the weld metal is minimized.

Peening of welds shall not be permitted.

Preheating temperature shall be raised by 50°C above that qualified, for fillet and T butt welds with

root gap exceeding 20mm.

Welding joints shall be fully protected by shelters from the effects of inclement weather (wind, air

draughts or chimney effects). Gas metal arc welding (GMAW) shall be permitted in workshop only and

special care shall be exercised to protect the weld arc from air draughts.






HEN 0000 ST SP 0002 51 of 102

5.1.2 Preparation and Fit-up

Surfaces to be joined by welding and extended adjacent areas shall be thoroughly cleaned to remove

all material or substance detrimental to welding.

Whenever practicable, clamps, magnets, holding devices or other setting-up fixtures shall be used in

assembling structural members in order to avoid tack welding.

Mechanical grinding of oxycut surfaces to be welded is required (see also Section 9.6).

Arc gouging to open tight grooves are permitted, provided is followed by grinding to bright metal.

Before welding the stub to node can, the relevant welding area on the can shall be 100% UT to detect

for laminations. If laminations shall be found Contractor shall try the node chord in such a way to find

an area without laminations. A similar control shall be performed on plates in the position of joint

between pad eyes and main beams.

5.1.3 Tack Welding

Otherwise spacers shall be employed prior to tack welding to ensure correct root gap spacing.

Tacking shall be done within the bevels. Tack welding shall be performed by qualified tack welders

and an approved qualified welding procedure, including preheating requirements.

Steel bars tacked inside the bevel shall be permitted if their position is clearly marked on base material

and that Company may verify their removal. Steel bar material shall be similar to base material type or

lower grade.

All tack welds, on structural class "a, b, c", shall have a minimum length of 4 times the weld thickness,

with a minimum of 100mm; all other structural classes the minimum length is 2 times the weld

thickness or 50mm whichever are the major. Tack welds may be incorporated into double side main

butt welds provided they are sound, have been executed by qualified welders (not tack welders), and

have their ends grounded and feathered.

Tack welds with a length of 50mm or greater that have shown cracks and when the crack is believed

to extend to the bevels, shall be MT on all the interested areas after removal of defective points and

before commence welding.






HEN 0000 ST SP 0002 52 of 102

5.1.4 Weld Interruption

Welding shall be a continuous operation as far as practical. For components of class "a, b, c" very

constrained and for mud-mats, preheating shall never be discontinued before at least 1/3 of the joint

thickness bas been welded. When the above limit is reached the weld joint may be allowed to cool

down to room temperature: the cooling rate shall be minimized by wrapping the weld areas with dry

insulating blankets. After any interruption and before continuation of welding, the weld is to be

inspected visually for cracks.

5.1.5 Weld Profiles

As a minimum, weld profiles and weld finish shall comply with AWS D1.1 Section 5.24; in the case of

lack of fusion, incomplete penetration or for marginal indentation, the values shown in section 9.13 of

this specification shall not be exceeded.

The external and internal weld reinforcement must not exceed 3mm for welding thicknesses up to

25mm, 4mm for thicknesses up to 50mm and 5mm for thicknesses over 50mm. The excess

penetration in root welding, with GTAW process, shall not exceed 2mm

Weld profiles shall not interfere with the NDT technique specified: reshaping shall be carried out to this

purpose, if necessary. Weld profiles shall not be re shaped by use of a gas torch, or by other

unapproved means to change their appearance.

When specified on the Project Drawings the weld toes shall satisfied API RP2A Sect.11 requirements.

If necessary, the weld toe can be grinded to obtain the required profile as shown figure 5.1. Grinding

shall produce a smooth concave profile at the weld toe with the depth of depression penetrating into

the plate surface to at least 0.5mm below the bottom of any undercut, but not deeper than 2mm or 5%

of the thickness, whatever the bigger, below the surface.

Localized unacceptable undercuts at the weld toe region of any stub to node can welds shall be

removed by the technique mentioned above.






HEN 0000 ST SP 0002 53 of 102

5.2 Welding Sequences

Contractor shall develop welding sequences to control tolerances within specification and prevent the

build-up of excessive residual internal stresses in the structure. No welding shall be carried out between

pretension parts.

Welding sequences are to be defined, to the Company's approval, for complex items (e.g. nodes with

more than four stubs, pile clusters, etc.) including:

WPS to apply;

sequence of items welding and welding direction and way;

number and location of welders at each stage of assembly;

position of preheaters and shelters;

post heating (if applied).

5.3 Temperature

Welding is not allowed if weldment temperature is lower than 5°C. In these cases preheating is

mandatory to the required minimum temperature prior to begin welding. Preheating shall be applied to

an area of 100mm minimum from bevel borders.

Definite methods and procedures shall be established for all operations involving preheat and interpass

temperature control. Thermic crayons shall be used only outside the weld bevel. Temperature check or

measurements shall be done at 50mm minimum from bevel borders and on back side where

accessible; temperature reading on weld bead is for interpass temperature measurement only.

5.4 Repairs

Contractor shall prepare a written repair weld procedure, for each repair, including details of removal

methods, weld area preparation, etc. Repair shall be carried out as per qualified procedures only.

Defects removal for repair shall be carried out by any method foreseen by this specification and shall

produce a clean uncontaminated surface for the repair weld execution.






HEN 0000 ST SP 0002 54 of 102

5.4.1 Repair of Finished Welds

Defects in weld metal may be repaired without Company's approval provided the repair

procedure is qualified.

A register shall be kept by Contractor that details the location of all repairs, the defects, the names of

the original welders, dates and repair procedures.

Contractor shall have a relevant NDT documentation to identify the exact defect position. Minimum

excavation length shall be 100rnm. Excavations closer than 10mm shall be linked into a single

excavation.

Serious failures, like cracks, will be treated in a proper way. When detected, they will be examined in

order to establish the originating reasons; then they will be repaired.

The crack shall be removed by either grinding or arc-air gouging plus grinding to sound metal; grinding

shall be carried out in a 50mm area from both ends of the crack, which is determined by MT or PT.

The MT shall be extended to base material surface to detect possible propagation. UT shall be used to

assure defect removal. All NDT shall be carried out in optimum conditions of accessibility.

Preheating temperature for repairs shall be 50°C higher than the relevant WPS temperature

requirement.

Re-inspection shall be as per the original inspection technique and shall include all weld metal within

100mm of the repair. The areas interested to the cracks, after the repair, shall be UT detected.

All weld repairs shall be executed prior to any stress relieving heat treatment, when required.

In case that, after repair completion, NDT shows the presence of new unacceptable defects, the

reasons are to be cleared up and reported to the Company prior to proceed with the new repair. In any

case the excavation for the new repair is to be widened in order to reduce residual stress

concentrations.

Cosmetics grinding for eliminating shape defects on cap layers are permitted only if necessary, but are

not considered repairs.






HEN 0000 ST SP 0002 55 of 102

5.4.2 Bevel Repairs

Local grinding may be used to remove notches up to 5mm deep in order to give an even profile.

Notches deeper than 5mm shall be ground out and the face buttered according to the applicable

requirements of this specification.

5.4.3 Buttering

Buttering shall be applied as a corrective action only. Buttering shall be done using qualified welding

procedure.

Following buttering bevel preparations shall be re-established by grinding or machining to the

acceptable limits. Buttered area of double side welding shall be 100% MT prior the execution of root

pass, if applicable.

Buttering on stub to can node welds may be applied to the node can side instead of stub side.

The exact root opening shall allow the closure with a single pass by the qualified procedure.

5.4.4 Base Metal Repair

All corrective action shall be in accordance with the approved procedure.

All boundaries of cavities resulting from removal of detrimental defects shall be faired to a slope of at

least 4 to 1.

The repair of failures by grinding shall follows the procedures set in EU163 rules with the following

limitations:

the residual thickness after grinding shall be not less than 93% of the nominal thickness;

the maximum depth of the grinded area shall not be greater than 3 mm;

the depressions shall be radiused to the other surfaces;

the maximum extension of the grinded area shall not be greater than 5% for each m2 of surface.

To verify the complete removal of discontinuities, the grinded areas shall be MTI tested.






HEN 0000 ST SP 0002 56 of 102

The repair by welding is allowed only if previously authorized by the Company and if executed in

conformity with EU163, with the following limitations:

the repair by welding is carried out by qualified welders and in accordance with qualified

procedures. Reference is made to Cap. 3. and 4. for what concerns the qualification of procedures

and welders;

the weld is MTI and UT tested. The acceptance criteria of the UT test are as described in

paragraph 9.13.3.

For Z quality products no repair is accepted.

5.5 Closure Welds

Qualified root gap values, including qualified tolerance, may be difficult to be reached during assembly

phase. In this case only class "a, b" closure welds shall be carried out in accordance with the following

requirements. WPS to apply shall be chosen by the Contractor considering actual situations and bevel

mismatch. Special and limit situations shall be approved by Company. All other weld class may be

carried out with subscribed WPQ.

Considered welds are single side only. These welds shall be carried out with a special WPQ

considering a greater root gap, or with a different WPQ. The following table indicates the various

possibilities.

Table 5.1 – High Root Gap

Element Thickness (mm)

Actions t ≤ 20 t ≤ 40

Limit root gap values (mm)

4 4 Normal

10 12 Buttering

18 20 Backing Strip

> 18 > 20 Insert






HEN 0000 ST SP 0002 57 of 102

Following possibilities (fig 5.2) apply whenever root gap exceeds qualified value:

Figure 5.1 – High Root Gap






HEN 0000 ST SP 0002 58 of 102

6mrn buttering on each bevel with 12mm as maximum root gap (see Section 3.7.3.);

otherwise GTAW process may be used both for buttering and air closure. In this case only

Charpy-V test, in root region, 1mm under surface is required;

permanent backing strip with root gap values higher than 12mm up to 20mm (Section 3.7.5.)

with root gap higher than 20mm an insert is required, following the tolerance values indicated in

Section 6.3.8 and 6.3.9.

Welder’s qualification for first pass shall be carried out accordingly, following the relevant requirements

of this specification.

Contractor shall identify all closure welds on fabrication drawings, indicating the applied procedures.

5.5.1 Normal and Buttering Actions

The requirements are relevant to joints with root gap between 3mm and 12mm. SMAW and GTAW

process may be used to carry out the first two passes.

GTAW root process used both for buttering and filling, follows mixed process requirements including

KCV test in WM and HAZ, two macro sections, hardness and bends.

Buttering carried out by SMAW process does not require qualification with thickness up to 6mm.

First pass with root gap exceeding 4mm, with SMAW process is not allowed.

5.5.2 Permanent Backing Strip

In this case the following requirements shall be fulfilled:

backing strip shall not be tack welded to member outside of bevel, otherwise joint shall be cut,

even if completed;

backing strip dimension should not be greater than 4mm thickness and 40mm wide.

Strip interruptions shall not be wider than 1mm. For a girth weld a maximum of three continuous

strips may be used.






HEN 0000 ST SP 0002 59 of 102

Backing strip material shall be EN 10025 S235JR, or equivalent, in as rolled conditions. No KCV are

required on base material.

WPQ shall be qualified according to requirements of Section 3.7.5.

5.6 Stress Relieving Post Weld Heat Treatment

Stress relieving is to be performed in accordance with a PWHT procedure specification. This

specification is to detail heating and cooling rates, temperature gradients, soaking temperature range

and time, heating facilities, insulation, control devices and recording equipment. The procedure is to be

submitted to the Company's approval.

For every application procedure shall include a drawing of the items, supporting method and location of

all thermocouples. Support positioning shall be defined assuming a yield strength of 35MPa at soaking

temperature. Additional temporary stiffeners shall be used to avoid any final distortion of the items free

ends when D/t ratio is above 40.

All temperature charts shall be signed, dated at both start and finish points, marked with a clear

identification, and filed.

The stress relieving post weld heat treatment is required in the following cases;

Welds in tubular nodal joints of class “a” and “b”

For the whole pre-fabricated node if chord wall thickness is greater than 50mm or any of the stubs has

wall thickness greater than 40mm.

Welds of Class “b”

When reference weld thickness is greater than 50mm.

Post weld heat treatment of thermo mechanical control process streels (TMCP) shall be avoided as far

as practicable. In case post weld heat treatment of TMCP is absolutely required, it can be achieved at

elevated temperature not exceeding 590°C±10°C.






HEN 0000 ST SP 0002 60 of 102

5.6.1 Heat Treatment Conditions

Soaking temperature is to be within the range 590°C±10°C: therefore temperature all over the points

of the item to be treated shall be within this range.

Soaking time is to be 2.5 minutes for each millimetre of thickness of the thickest member in item, with

a minimum of 1.5 hours.

Soaking time begins when the lowest measured temperature value is within soaking temperature

range.

The heat treatment may be done introducing the item in the furnace, or in local manner; this choice

depends by the item dimension only.

5.6.2 Furnace Heat Treatment

The item may be introduced in the furnace if this has not a temperature over 300°C. The same may

not be taken out from furnace if its temperature is over 300°C. Cooling down below 300°C shall be in

air.

Item temperature shall be recorded from introduction in the furnace until taking out. Rate of increasing

and decreasing temperature is to be 55°C per hour maximum for temperatures above 300°C. The

temperature difference on the item, during heating and cooling phases, measured along symmetry

lines and planes shall not exceed 50°C; between the outside and the inside surface is not to exceed

50°C; between any point of the item far not less than 4500mm shall not exceed 150°C.

Temperature shall be recorded continuously and automatically. Thermocouple locations shall be

selected to ensure that the whole item, or item part, being treated is within the range specified;

additional pyrometers should be used to check that undesirable thermal gradients do not occur.

During the stress relieving heat treatment the furnace atmosphere shall be controlled so as to avoid

excessive oxidation of the surface of the item. There shall be no direct impingement of flame on the

item. No parts of the item shall be closer than 200mm from furnace sole plate, or closer than 300mm

from inside walls.






HEN 0000 ST SP 0002 61 of 102

5.6.3 Local Heat Treatment

Local heat treatment is to be carried out by electrical heating: resistance or induction.

The procedure specification for stress relieving shall contain the calculations of the necessary heat

power and insulation, the temperature measurement point, the actions to take in case of temperature

difference exceeding the above values and in case of any thermocouple damage. Any local stress

relieving heat treatment is subject to Company’s approval.

In circumferential seams the width of the heated band shall be not less than 5√(Dt/2), with weld in the

centre. Sufficient insulation shall be fitted to ensure that the temperature at the edge of the heated

band is not less than half the peak temperature. The adjacent portion of the item outside the heated

zone shall be thermally insulated such that the temperature gradient is in accordance with above

paragraph. A minimum total insulated band width of 10√(Dt/2) is recommended for this purpose.

5.7 Welding Parameter Checking

Welding parameter check may be applied after to have verified the first production coupon weld

soundness.

Before starting fabrication Contractor shall submit to Company's approval the procedure and checking

methods that he intends to use to this purpose. Welding parameters checks shall be continuous all over

the production. Company anyway may require a production test coupon whenever he considers

necessary.

Acceptability of welding parameter checking procedure is solely to Company.






HEN 0000 ST SP 0002 62 of 102

6. FABRICATION

6.1 General

All fabrication and erection shall be in accordance with these specification requirements.

Work shall not be performed when weather does not permit satisfactory workmanship or when particular

conditions prevent adequate inspection.

6.1.1 Dimensional Control

Fabrication shall proceed on a flat and level surface and frequent checks shall be made on the

supports and blocking, and any movement out of the level shall be immediately rectified by appropriate

shimming to re establish a level plane.

The Contractor shall survey and control dimensions before fit-up for welding of additional components

and sections. Dimensions shall be checked at each stage in accordance with the fabrication procedure,

tolerances (if given) and the final survey shall meet the defined tolerances. The Contractor shall

submit his dimensional control procedures indicating proposed methods of monitoring dimensions,

their tolerances compatibility and construction method philosophy to the Company before commencing

fabrication.

6.2 Forming

6.2.1 Tubular Fabrication

Tubular may be formed with calendar rolls axis both parallel or orthogonal to the longitudinal axis of

the plate (plate rolling direction).

Tubular may be re rolled after welding in order to reduce deformations. Re-rolling carried out with an

equipment type different from that used for forming shall be subject to Company's approval.

6.2.2 General

Contractor is to qualify each complete forming process, including final re-forming calibration process,

when forseen.






HEN 0000 ST SP 0002 63 of 102

Qualification shall be carried out within the terms and as specified in the section 6.2.7.

The forming shall be not carried out in the temperature range from 200 to 450°C or above 800°C. TM

steel shall not be hot formed, i.e. above 580°C.

6.2.3 Surface Preparation

Plates having surface condition that may impair the forming operation or which may have scale

incorporated into its surface shall be restored by blasting, SA 2 level, before forming. All defects that

may appear after forming shall not exceed 0.3mm in depth.

6.2.4 Cold Forming

Cold forming is considered the forming carried out at ambient temperature.

When the cold forming is executed on plates which have already pass successfully through an ageing

test, with a strain value of 5% and the true deformation is higher, the plate shall be submitted to a new

ageing test with a strain value not less than the real one, or to a thermal relieving treatment. For

assembled elements, the relieving treatment can be executed just before the start of operations.

When the cold forming is executed on a plate which has not been submitted to any ageing test, and

the strain value is above 3%, the plate shall be submitted to an ageing test with a deformation value

not less than the real value; as an alternative, the item shall be submitted to a thermal relieving

treatment before the start of operations.

In all the other cases, cold forming can be carried out on plates without any additional test.

6.2.5 Warm Forming

Warm forming is carried out from 450°C up to 600°C.

TM steels should not be formed at temperature greater than 580°C.

6.2.6 Hot Forming

Hot forming is carried out beyond 600°C up to 800°C.






HEN 0000 ST SP 0002 64 of 102

Forming process shall be followed by normalization heating treatment to restore the mechanical steel

characteristics

6.2.7 Hot Straightening

Hot straightening may be applied to recover excessive deformations caused by welding or stress

relieving. All class "a" elements, deck legs, padeyes and so on shall not be submitted to hot

straightening in any care. Hot straightening shall be carried out to a Company's approved procedure.

The following requirements shall be fulfilled:

gas torch may be used, but heated areas shall not be larger than 60mm;

maximum temperature shall not be greater than 550°C and shall be kept under full control at

least by means of portable contact thermocouple;

steels with 500MPa tensile strength, or higher, shall not be fast cooled, by water or other means.

All hot straightening operations shall be witnessed by Company.

6.3 Welded Connections

6.3.1 Double Side Welding

Double side welding shall be carried out whenever possible. In particular:

In longitudinal and circumferential joints of tubular and node cans having diameter 800mm and

greater. Limitations to this statement are permitted only in case of non accessibility to back side

of the weld;

In brace-to-can welds where brace has internal diameter 600mm or greater.

6.3.2 Welding Grooves

Contractor is to prepare his own standard weld joint groove preparation in accordance with the

indications given on the fabrication drawings and WPS qualified.

Where the joint is accessible from both sides, double side groove preparation, X or K type, maybe

used to join members with thickness greater than 25mm; one side groove preparation, V or 112 K,






HEN 0000 ST SP 0002 65 of 102

may be used to join members with thickness 25mm or less. Contractor may choose a desired welding

groove provided all full penetration requirements are fulfilled.

Bevel inspection shall be in accordance with the section 9.6.

Root back gouging is always required in double side joints.

6.3.3 Mismatch

The butt joint mismatch of welded plate, pipe or structural shape edges shall not exceed the table 6.2

values:

Table 6.2 – Mismatch Values

Joint Type Mismatch:

The lesser of 0.1t or:

Double Side Longitudinal

Circumferential

4mm

3mm

Single Side Longitudinal

Circumferential

3mm

3mm

When members of unequal size are joined, the larger member shall be prepared with a 1/4 tapered

transition. The requirements apply both to thickness and width (e.g. beams flanges) dimensions.

Worked taper in double sided joints are not required when thickness difference is 1.15t or less.

6.3.4 Longitudinal Seams

When tubular members are fabricated from two or more welded barrels, the longitudinal seams axes

of adjacent sections shall be staggered at least 300mm.

6.3.5 Node Can Welds Intersecting Stubs

Longitudinal and circumferential chord welds shall be separated from stub to chord welds as indicated

in construction drawings, typical node. Otherwise the following requirements are to be fulfilled.

flush grinding of the outside area of chord welds intersecting the stub, extended for 150mm at

least on both stub sides;






HEN 0000 ST SP 0002 66 of 102

MT and UT on ground area;

The distance between longitudinal stub seam and any node can seam type measured between weld

toe and weld toe should be in any case not less than 51mm.

6.3.6 Node Can Welds and Ring Stiffeners

The distance between ring stiffeners welds toe and circumferential chord weld toe is to be at least the

chord thickness or 75mm, whichever is greater.

6.3.7 Cones

Circumferential welds within cone are not allowed, unless approved by Company or specified on the

construction drawings. All cones shall be right conic frustum.

6.3.8 Pipe and Node Splices

The minimum distance between two circumferential welds shall be 1m or two diameters, whichever is

greater.

There shall not be more than 2 splices in any 4m of pipe.

Company's approval shall be necessary for circumferential welds within cones and node stubs.

6.3.9 Beam Splices

In cantilever beams no splice shall be located closer to the point of support than 1/2 of the cantilever

length.

In beams with two or more supports there shall not be splices in following positions (fig.6.1):

in the middle 1/4 of the span;

in the 118 of the span nearest to any supports;.

not closer than 1m to any support or node.

When beam shall be welded on flange beam, the flange beam area shall be UT tested to verify the

laminations absence.






HEN 0000 ST SP 0002 67 of 102

Figure 6.1 – Beam Splices






HEN 0000 ST SP 0002 68 of 102

6.4 Welded Attachments

Welded attachments to the structure not shown on the construction drawings shall not be permitted

except for temporary and non-structural attachments. In this last case too they must be maintained at a

minimum number.

In these cases welding shall be allowed, provided that the attachment thickness is not greater than

20mm and the welds location are not closer than 51mm from any weld.

All attachments shall be welded to the structure according to these specification requirements and

approved procedures.

Temporary attachments welding to nodes or PWHT elements are not allowed.

After the structure completion, all welded attachments shall be removed by flame cutting 5mm from the

base material, followed by smoothing corners.

Where paint is foreseen flush grinding is required.

Attachments shall not be removed by hammering or any other method that may cause mechanical

damage to the surface.

The interested area shall be visually controlled and testing maybe carried out to demonstration of

material soundness).

6.5 Site Assembly

Contractor shall consider, during site assembly, all temporary erection loads imposed on the structure

from supports, jacking and slinging at each stage of the structure assembly.

Contractor shall consider, during site assembly, the local or overall stability from self weight and

environmental loads. These include scaffolding, staging, temporary cranes, welding shelters and

temporary works, at each stage of the structure assembly.

Contractor shall provide during the assembly phase storage for all items, to prevent their damage from

environmental.






HEN 0000 ST SP 0002 69 of 102

Contractor shall make provision for alignment correction at each stage of the structure assembly.

6.6 Manufactured And Miscellaneous Items

6.6.1 Bar Grating

Bar grating shall be cut to dimension and installed as shown on the construction drawings.

Unless otherwise restricted by construction drawings, bar grating may be attached by either tack

welding or bolting.

If tack welded, each bar shall be pressed in firm contact with the underlying structure and secured with

a minimum 50mm line tack weld. The tack weld and the surrounding heated area of zinc galvanised

bar grating shall be touched-up according with the relevant painting specification or as per procedure.

6.6.2 Steel Floor Plate

All butt type joints shall be welded to produce an 85% fused joint minimum. All floor plate under-side

shall be 100% seal welded to deck stringers and other supporting, to seal all facing surfaces from

corrosion. Seal fillet welds shall have a minimum leg length of 4mm.

Seal welds and butt joints shall be staggered at least 50mm.

Steel floor plate shall not present subsidence higher than 3mm measured with a 1200mm length

gouge.

6.7 Finishing of Surfaces

As fabrication of various items or portions of the structure is completed, the Contractor shall remove all

welds, burrs, tack welds and other marks made by scaffolds or temporary bracing used in the

fabrication procedure.

All arc-strikes and burn marks shall be ground smooth, visual and MT inspected. The areas of

components "a, b and c" interested shall be carefully examined.






HEN 0000 ST SP 0002 70 of 102

6.8 Rat Holes

Rat holes are required when shown on construction drawings and whatever they are necessary to full

penetration weld execution. In this case only Contractor shall define the relevant solution, with

Company's approval.

Rat holes radius shall be as small as possible, but in conformity with the necessity to carry out adequate

operations. The surfaces shall be smooth and without any indentation.

Full penetration welded stiffeners shall blend onto parent material inside rat hole.

Fillet weld shall be returned through the rat hole.

When weld joint crossed is fillet welded, a 45° clip of sufficient width may be provided on stiffener comer

in order to shape it onto weldment and facilitate complete stiffener fillet welding.

Rat holes in structural elements to be painted; otherwise iron mastic approved by Company may be

applied. In these cases the use of rat holes shall be minimized.

6.9 Bolted Connections

Bolt holes shall be drilled at right angles to the metal surface and shall have at least a diameter 1.5mm

larger than the bolt diameter.

Bolts shall be freely insertable into the holes without damage to the thread. Bolt heads and nuts shall

rest squarely against the metal surface.

Unfinished bolts transmitting shear shall be threaded to such a length that no more than one thread will

be within the grip of the structural members.

All bolts shall be of a length such that they will extend entirely through but no more than 6mm beyond

the nut and locknut.

After final tightening, nuts shall be locked by tab washer, cotter pin or locknut. Equipments, bolt material

and tightening torque shall meet the requirements specified on construction drawings.






HEN 0000 ST SP 0002 71 of 102

7. PREFABRICATED ITEMS TOLERANCES

The Contractor shall provide personnel with qualified surveyors, equipment and instruments, with

current valid calibration certificates, necessary for monitoring and controlling dimensions and tolerances.

The following sections give the admitted tolerances for every measurable dimension and shape of

structural elements.

7.1 Fabricated Tubular Nodes and Cones

7.1.1 Circumference

Circumference measured with tape shall not differ from theoretical value more than ±1% of nominal

circumference or 10mm, whichever is less.

The measurement shall be carried out at 600mm from any tubular splice and at tubular ends.

Intermediate measured values shall not differ more than 1.5 times the above.

The circumferential tolerance shall not be reason for increasing the mismatch tolerated by this

specification.

7.1.2 Ring Stiffeners out of Circularity

For each ring stiffener shall be checked the difference between the actual radius and the average

radius, in different points.

This difference shall not be greater than 0.25% of the external ring stiffener diameter.

The average radius defined by optimum centre and the radius measurements, in various position,

relevant to the optimum centre shall be calculated in accordance with a procedure, approved by

Company, based on EEMUA 158 optimum centre out of circularity.

7.1.3 Ovality (General)

Ovality is intended as the difference between the maximum and the minimum diameters, measured

either internally or externally, at the same section.






HEN 0000 ST SP 0002 72 of 102

Ovality shall be checked at each item end, at each 3m interval, at each circumferential seam, and at

midway between two ring stiffeners.

The following table applies.

Table 7.1 – Ovality Values and Measurement Numbers

Diameter Value Number of Measures (*)

≤600 1% of diameter Two diameters

≤2000 Greater of 6mm or 0.75% D Four diameters

> 2000 Greater of 15mm or 0.75% D Six diameters

Two diameter measurements may not be at 90° between them, but carried out in the position with

maximum and minimum value.

Measuring method, with more than two diameters, may be equally spaced instead of maximum and

minimum position.

7.1.4 Local out of Roundness

Local out of roundness shall be measured by means of a 20° gauge having a theoretical tubular form,

and the measurement is verified all over the circumference (360°).

Local out of roundness shall not be greater than 0.4% of the diameter. This control shall be carried out

on tubular elements with diameter greater or equal than 1000mm.

7.1.5 Local out of Straightness

Local out of straightness is the deviation of the shell plate from its axis.

This value shall not exceed 20% of the wall thickness.

Local out of straightness shall be checked on tubes with nominal outside diameter greater than

2000mm or with nominal outside diameter/wall thickness ratio greater than 65. The check shall be

either on the inside or outside, and the positions shall be those indicated in table along all tubular

element.






HEN 0000 ST SP 0002 73 of 102

Table 7.2 – Local out of Straightness

Type of Joint Check Location

Unstiffened tubular 45° intervals of arc with template

L=3000mm

Stiffened tubular node barrels 20° intervals of arc with template

L = distance between stiffeners or 3000mm in other uses

Manways after welding at the centre and manway quarter points with template L = 1000mm

7.1.6 Out of Straightness

Structural classes "a, b, c" members, excluded piles, out of straightness tolerance is the greater of

0.1%L or 3mm, but not greater than 12mm.

Straightness shall be checked in at least two perpendicular planes.

7.1.7 End Perpendicularity

End perpendicularity shall be held within 3mm. This tolerance shall not be cumulated with weld root

gap tolerance (fig.7.1).

Figure 7.1 – End Perpendicularity






HEN 0000 ST SP 0002 74 of 102

7.1.8 Prefabricated Nodes

Length tolerance of node cans, stubs and cones shall be within 0 + 100mm from length shown on

fabrication drawings.

Actual stub centre line is intended as the intersection of two orthogonal diameters at both ends of the

stub; one of the diameters is parallel to the longitudinal axis of the node chord.

Each actual stub centre line shall be kept within 10mm cylinder from its theoretical position shown on

the fabrication drawings (fig 7.2).

Figure 7.2 – Node Working Point

7.1.9 Ring Stiffeners

Rings stiffeners in node cans and cones shall be fitted, with respect to their theoretical location shown

on fabrication drawings to an accuracy of ±1/3 stiffener thickness but not more than 6mm. Stiffeners in

tubulars shall be fitted with an accuracy of 12mm.






HEN 0000 ST SP 0002 75 of 102

The internal or external ring stiffeners inclination shall be within 1% of the nominal web depth but not

more than 6mm. For ring stiffeners in nodes and in node cones the same tolerance is 0.5%h with

maximum value of 3mm.

The maximum bow in the web of an internal or external ring stiffener shall be within 1% of the nominal

web depth, but not more than 3mm.

The deviation of the flange edge, of an internal or external ring stiffener, from the diameter measured

at the flange centerline shall be within 5% of the nominal flange width.

If ring stiffener is fabricated in two or more pieces and if flange is required the buttwelds mismatch

shall not exceed 0.1 stiffener web or flange thickness nor 3mm (fig 7.3).

Figure 7.3 – Ring Stiffener






HEN 0000 ST SP 0002 76 of 102

7.2 Rolled or Fabricated Beam

Fabricated structural steel section tolerances shall comply with AWS D1.1 Section 5.23.

For permissible variations from flatness of web see AWS D1.1 paragraph 3.5.1.6.

All other tolerances not considered here shall be in accordance with EEMUA 158, section 6.2.2.1.

7.2.1 Global Tolerances

Structural class "a, b" members, no hollow sections, out of straightness and verticality is the greater of

0.1%L or 3mm, but not greater than 12mm.

The out of straightness and verticality tolerance for girder and beam with hollow section is the greater

of 0.2%L or 5mm but not greater than 25mm.

7.2.2 Local Tolerances

Flange eccentricity shall be equal to 0.02b, with maximum value equal to 6mm. Tilt and roof shape

shall be equal to (1+0.01b)mm but not greater than 6mm, with b is the flange width and t the thickness.

(fig. 7.4)

Figure 7.4 – Roof Shape






HEN 0000 ST SP 0002 77 of 102

Web girder twisting shall be equal to (1+0.01h)mm, but not greater than 10mm, where his the web

height in millimetre. Web bow shall be equal to 0.01h with maximum value equal to 0.5t, where t is the

web thickness.

7.2.3 Web Stiffener

Web stiffeners location between girders flanges shall be within tolerances values.

Web stiffeners shall be fitted with respect to their theoretical location to an accuracy of half stiffener

thickness, but not greater than 6mm. Web stiffener out of straightness shall be within 0.15%L, but not

more than 3mm. The outstand of web stiffener under load bearing surfaces shall be within 0.5% of the

maximum web height but not more than 3mm of a perpendicular set out from two girders flanges3mm

(fig. 7.5).

Figure 7.5 – Web Stiffener

7.2.4 Fillet Welds Execution

Weld passes shall be continuous to prevent any risk of crevice corrosion. Welds shall be returned

through the rat hole, when present.






HEN 0000 ST SP 0002 78 of 102

7.3 Stiffened Plate Panels

The following applies, with reference to fig. 7.6:

Figure 7.6 – Roof Shape






HEN 0000 ST SP 0002 79 of 102

Table 7.3 – Tolerances for Plate Panel

Tolerance Type Tolerance Value Limiting Value (mm)

Plane out of position 0.3%L 10

Global lateral deflection between

principal stiffeners 0.5%L1 10

Global lateral deflection between

secondary stiffeners 0.15%L 15

Table 7.4 – Tolerances for Plate Panel Stiffener

Tolerance Type Tolerance Value Limiting Value (mm)

Inclination ay 2.5%h 5

Out of position Py 5%h 10

Nodal out of position Py 5%h 3

Out of straightness Sv both orthogonal

and lateral the plate plane 0.5%L1 5

Where, L1 is the distance between two consecutive stiffeners

h is height of the stiffeners

7.3.1 Stiffeners Forming Cruciform Arrangements

Where a combination of stiffeners (ring, diaphragm, web) from a cruciform arrangement with other

member or stiffener the mismatch of the alignment through the joint shall be according to table 7.5.

Table 7.5 – Mismatch Value

Thickness Mismatch

t3 > t1 and t2 T3 / 2; max 10mm

t2 > t3 and t1 T2 / 2; max 6mm

For t1, t2 and t3 identification, see fig. 7.7.






HEN 0000 ST SP 0002 80 of 102

As-built dimensions shall be used to align members. UT check shall be performed where external

measurement can not guarantee the alignment.

Figure 7.7 – Mismatch on Cruciform Joints

7.4 Other Fabrication Details

7.4.1 Weld Beads for Grouting

Weld beads position and size shall be in accordance with the construction drawings. The weld beads

pitch is to be constant throughout the zone where weld beads are required and are to be kept equal

between sleeves and piles.

Tolerance on position of each weld bead is ±5mm with respect to what required on fabrication

drawings.






HEN 0000 ST SP 0002 81 of 102

The height of the bead shall to be a tolerance of 0 to +2mm.

Weld beads distance from circumferential barrels butt welds shall not be less than 51mm, measured at

weld toes. The barrels length shall therefore be defined also taking into account the above

requirements. However, not more than one weld bead per sleeve may be out of pitch.

7.4.2 Opening and Penetration Holes

The centerline point of any opening and penetration shall be within a tolerance of ±10mm of the

theoretical central point.

The actual size of any opening shall be within a tolerance of ±2mm of the theoretical dimensions.

See fig.7.8 for indication.

Figure 7.8 – Openings and Penetrations






HEN 0000 ST SP 0002 82 of 102

8. FINAL FABRICATION TOLERANCES

Final fabrication tolerances shall be within the tolerance values specified here below.

8.1 Position of Nodes

The node working point (intersection point among items axis measured on structure) (fig. 7.2) shall be

positioned within the error sphere whose radius is indicated in Table 8.1, relevant to the theoretical

position shown on fabrication drawings.

Table 8.1 – Nodes Positions

Node Type Tolerance

Jacket and Deck Matching Nodes 6mm

Other Leg Nodes 10mm

Other Nodes 15mm

Table 8.2 shows the tolerance values of some structural dimensions, as an example of said above.

Table 8.2 – Distance Tolerances

Measures Tolerance (±)

Length between first and last node working points on Jacket Legs 16mm

Distance between working point not involving one leg nodes 30mm

Placed on the same plane involving one leg nodes 25mm

Distance between abutting Jacket and Deck node working point 12mm

8.2 Deck Plans

8.2.1 Deck Section Columns

The columns intersections centre (item axes intersection centre) measured on the structure shall be

within the error sphere, whose radius is indicated in Table 8.3, relevant to theoretical fabrication

drawings position.






HEN 0000 ST SP 0002 83 of 102

Table 8.3 – Header Position

Node Type Error Sphere Radius

Beams on column

6mm Beams on stringer

Beams on principal beams

As said above, Table 8.4 gives, as an example, the overall distances and elevations tolerances

measured on structure.

Table 8.4 – Structure Measurement

Measures Tolerance (±)

Column distance

12mm Header distance

Header elevation difference

Indicated tolerance shall not be higher than bevel mismatch. Tolerance among same level column

shall not be higher than planarity and bevels mismatch limit.

8.2.2 Deck Section Plate

Plates on deck beams shall not have sags higher than ±3mm relevant to theoretical bearings level.

8.2.3 Working Plane Position

Deck and modules working plane position shall have a vertical outstand lower than R/500, with 9mm

as maximum, relevant to the theoretical plane; R is the distance from reference point.

The maximum number of water collectors shall be defined on construction drawing and Company shall

define their position after welding of steel floor plates.






HEN 0000 ST SP 0002 84 of 102

8.3 Handrails

Fabrication and erection shall be performed to a degree of accuracy that the top rail shall be level to the

eye, and the handrail shall be plumb.

8.4 Walkways, Landings and Stairways

Walkways, landing and stairway shall be located within the following tolerances, relevant to the

fabrication drawings.

Table 8.5 – Tolerance for Landing and Stairway

Elevation ± 12mm

Planarity ± 6mm each 3m length

Planimetric Position ± 12mm

Distance among steps shall not be more than 3mm from theoretical position.






HEN 0000 ST SP 0002 85 of 102

9. INSPECTION OF WELDMENTS

9.1 General

All welds are to be subjected to non destructive examination (NDT)as fabrication and construction

proceed, as per a proper schedule and relevant drawings supplied by the Contractor.

NDT on weld class "a, b, c" shall be carried out only 48 hours after completion of welding. The same

requirement for weld class "d" with thickness higher than 20mm.

NDT on weld class "e" and on all other classes not considered above may be carried out 24 hours after

welding completion.

Inspection and NDT prior to PWHT shall be at the Contractor discretion and shall not avoid further tests.

All NDT reports are to include all data that allows to repeat the examination in the same conditions.

Contractor shall formulate a quality control plan that shall contain mandatory NDT inspection and the

time when they shall be done. This plan shall be submitted to Company's approval.

9.2 Definitions

The following definitions are used:

NDT Non Destructive Testing

VI Visual Inspection

MT Magnetic Particles Inspection

PT Dye Penetrant Inspection

UT Ultrasonic Testing

RT Radiographic Testing

DAC Distance Amplitude Correction

HD Maximum Amplitude of Flaw Echo Height






HEN 0000 ST SP 0002 86 of 102

9.3 Reference Standards

The standards and codes of practice called up by this specification are considered at the latest edition

at time of contract award. They are:

API RP 2X

API Standard 1104

BS EN 462

EN 970

BS EN ISO 9934-1

ASNT-TC1A

Contractor shall equip themselves with copies of all the standards and codes referred to in this

specification and shall make them readily available to all inspection personnel involved on work.

9.4 Methods of NDT

Accepted NDT methods are RT, UT, MT, and PT. Their applicability shall conform to the following table.

UT may be used instead of RT on a case by case to be submitted to Company for approval prior to

commencement of UT.

Table 9.1 – NDT Applicability

Weld Classes a, b, c, d e

Joint t ≤ 12mm 12 < t ≤38mm T > 38mm all thickness

Butt RT

MT

UT

MT

UT

MT

MT

PT T-butt MT UT MT

Fillet MT

Table shall be integrated with the following requirements.

The indicated thicknesses are those referred to welding thickness.






HEN 0000 ST SP 0002 87 of 102

9.4.1 RT

For filing reasons the RT inspection is preferred to UT inspection, even if thicknesses are greater than

38mm, for reporting. UT shall be carried out for deck and modules beams, when the joint geometry is

such that RT is unappropriate.

Thickness limits are relevant to complete one crossed by rays.

RT in shop are to be preferably executed by X ray equipment. Gamma rays may be applied on yard

only or on large prefabricated items. Following isotopes do not require Company's approval: Yt up to

t=12mm; Ir for thickness from 10mm to 19mm with qualification of the procedure test; Ir and Yt up to

t=38mm; X rays for thickness above 38mm. The use of Co 60 is generally not acceptable.

Phased aray testing method may be substituted with RT & A scans UT due to more advantages, such

as above mentioned method (phase aray) capabilities, safety requirements, projects construction

progress and etc.

9.4.2 UT

UT may be applied for chevron cracks checks on SAW welds with thickness above25mm.

UT shall be applied when RT inspection is not possible (i.e. T joints) or when exposition time is higher

than reasonable values, and anyway after Company's approval.

Fillet welds class "a, b, c" mainly submitted to tensile stress, may be UT inspected against lamellar

tears and to verify the weld discontinuity; test percentage shall be 100%.

New UT procedures that permit both to correlate echoes with position on piece through scanner use

and to record on magnetic support may be submitted to Company's approval. Change of NDT

procedure based on these new techniques is solely at NDT level III acceptance.

9.4.3 MT

MT is the reference surface NDT methods for all welds of classes "a, b, c, d". The substitution with PT

for parent materials with minimum yield strength not greater than 275MPa requires Company's

approval. For weld class "e" and all classes bevel inspection, PT may substitute MT without approval.

9.5 Extent of NDT

Extent of NDT shall be as per following table.






HEN 0000 ST SP 0002 88 of 102

Table 9.2 – Extention of Not On Weld Classes

a b, c d e

VI 100% 100% 100% 100%

UT/RT 100% 100% 20% -

MT 100% 20% (1) 20% -

PT/MT - 100% - 20%

(1) The MT test for joints and closure welds adjacent to nodes shall be 100%.

(2) Use of RT or UT and PT or MT and required percentage shall be accepted by Company

9.6 Edge Inspection

Prior to assembly for welding, all edges shall be inspected to find any eventual defects.

The inspection of the bevel edges shall be carried out with VI/MPI

Some times after beveling and before fit up it’s mandatory to verify bevel quality using MPI

examination, it shall be addressed in this specification.

Any discontinuity extending 5mm and above shall be repaired.

9.7 Qualification of NDT Procedures

The Contractor shall prepare procedures for each of the NDT techniques he proposes to use, and

submit these to the Company's approval prior to commence any testing.

Company may require the qualification of some or all of the procedures, by demonstration of their

capability to detect known flaws.

9.7.1 Radiographic Testing (RT)

The procedure specification for the radiographic testing is to include at least the following information:

radiation source (X-rays or gamma rays. If gamma rays, type of isotope);

technique (equipment rating in voltage or curie, external or internal equipment single wall, double

wall/single image, double wall/double image);

B4

B4

B4






HEN 0000 ST SP 0002 89 of 102

geometric relationships (film focus distance, object film distance, radiation angle with respect

to weld and film, focal spot);

film type (trade name and designation);

intensifying screens (front and/or back material, thickness);

exposure conditions (kV, rnA, min, Bequerel, min);

processing (developing time and temperature, stopbath, fixation, washing, drying, etc.);

image Quality Indicator sensitivities in percent of the wall weld metal thickness based on sources

and film side indicators respectively;

density (the radiographs density measured on the sound weld metal image);

film coverage.

The representative radiographic procedures are to be qualified by making two radiographic exposures

of a welded joint with the same or typical configuration and dimensions, on a material equal to or

similar to that which is to be used in the structure.

In order to check the sensitivity, the above requirements apply also for double walls images.

9.7.2 Ultrasonic Testing (UT)

A procedure specification for the ultrasonic testing according API RP 2X is to be established, which is

at least to include the following information:

type of instrument

type of transducer;

frequencies;

calibration details;

surface requirements;

type of couplants;

scanning techniques;

recording details;

reference to applicable welding procedures;

material thickness and curvature range;

check of calibration.

The qualification test is to be performed under normal working conditions and at Company presence.






HEN 0000 ST SP 0002 90 of 102

The test pieces are to be available as reference all over the inspection work.

UT carried out by automatic equipment is generally acceptable, but submitted to Company's approval.

9.7.3 Magnetic Particle Inspection (MT)

A procedure specification for the magnetic particle testing is to be established which is to include at

least the following information:

materials and dimensions;

type of equipment;

surface preparation including background paint;

wet or dry method;

make and type of magnetic particle and contrast paint;

magnetizing current (for prod magnetizing: the prod type and spacing are to be stated).

No special procedure qualification test is required. The procedure is considered qualified based on

approval of the testing procedure specification.

9.8 Qualification of NDT Personnel

Radiographic, ultrasonic, and magnetic particle operators shall be qualified to EN 473 or an equivalent

rule. Moreover all ultrasonic operators shall be especially qualified in accordance with API RP 2X

paragraph 2.3.

A scheme for qualification of operators conforms to EN 473 or an equivalent rule shall be established by

Contractor. Contractor is responsible for manufacturing suitable test joints, including artificial and

natural flaws, representative of the construction configuration that must be carried out. Operators shall

examine the number of test plates defined by the above scheme and shall set a written examination.

The internal qualification of NDT personnel shall comply with EN 473.

EN 473 or equivalent level ill, as supervisor, is required within the project and within yard or shop

organization.






HEN 0000 ST SP 0002 91 of 102

If the qualification of the personnel is in doubt, the Company may require their interdiction to production

activities until their ability has been satisfactorily demonstrated.

UT operators are to be capable of:

calibrating the equipment;

performing an operational test under production conditions;

interpreting the screen display;

evaluating size and location of reflectors;

classifying reflectors as planar, cylindrical or spherical.

RT operators are to be fully capable of performing an operational test using the qualified radiographic

procedure.

Operators performing MT testing are to be capable of performing an operational test, using the test

method or technique that is to be applied in production.

9.9 Visual Inspection Execution

Visual Inspection shall be carried out in accordance with BS 5289. The stub to node weld inspection

shall be carried out with the aid of clipped disk.

9.10 Radiographic Testing Execution

9.10.1 General

Contractor shall prepare a document in which he indicates the radiation source (X and isotopes) he

intends to use in function of thickness ranges, worksite locations (yard, shops) and relevant to the

whole job conditions.

The film type utilized shall be as per ISO 5579.

The film shall be fine grained type KODAK INDUSTREX “C” or AGFA D7 or equivalent. However the

inspector and/or company/TPA may require the use of extra fine grained film as KODAK MX or AGFA

D4 or equivalent where a better quality of radiographic image is needed.






HEN 0000 ST SP 0002 92 of 102

Only lead reinforced screens are to be used.

The execution procedures for the radiographic control must be qualified when the source is not

accessible during the production control.

9.10.2 Examination

Image quality indicators shall be of the wire type as recommended by llWIIIS 62-60 or ISO Standard

and are to be placed on the source side. In case that the source side is inaccessible during production

radiography, only film side penetameters are required, but shall be marked with an "F" and the

procedure shall be qualified.

The image quality indicators are to be clearly identified, and the sensitivity of the source side indicator

is to be equal to or better than the requirements given in for "single wall technique". For "double wall

technique" the IQI sensitivity shall be calculated putting the total weld thickness penetrated, i.e. two

times the plate thickness plus the two weld reinforcements, at the denominator of the formula. In this

case the permissible IQI values shall be double of those indicated (ref. BS 3971, table 7). Radiographs

are to have a density at the weld metal image in the range 2.6 to 3.8 for the double images with a

minimum of 1.3. For single images the density shall be in the range 2.0 to 3.0.

If the multiple exposure technique is used, at least one penetrameter is to be recorded on each film. If

the panorama technique is used to include 100% of tubular girth weld in one exposure, a minimum of

three penetrameters are to be equally spaced around the circumference, at 120° one from eachother.

The maximum acceptable film lengths are defined by the film references.

9.11 Ultrasonic Testing Execution

9.11.1 Equipment

The equipment used for ultrasonic testing is to:

be applicable for the pulse echo technique and for the double probe technique;

cover the frequency range from 2 to 6 MHz;

have a flat screen accessible from the front for direction plotting of reference curves;

allow echoes with amplitudes of 5% of full screen amplitude to be clearly detectable under

test conditions;






HEN 0000 ST SP 0002 93 of 102

include straight beam transducers, and angle beam transducers of 45°; 60° and 70°;

satisfy vertical linearity according to ASME V and horizontal linearity in accordance

with ASTM.

9.11.2 Calibration

Calibration shall be in accordance with API RP 2X requirements.

For portable testing equipment the IIW/ISO calibration block is to be used.

For echo amplitude evaluation, a DAC reference curve is to be established and plotted on the

instrument screen. The reference block for gain calibration and construction of DAC is to be

manufactured from the actual production material and be in accordance with the requirements of API

RP2X for Level A.

DAC curve construction shall be in accordance with the indications of API RP2X. Equipment horizontal

and vertical linearity shall be always calibrated before the any examination beginning. Calibration of

the ultrasonic equipment is to be carried out whenever it has been out of function for any reason, and

whenever there is any doubt concerning proper functioning of the equipment.

9.11.3 Examination

Ultrasonic testing of production welds, shall be carried out in accordance with API RP 2X and with the

following requirements.

The weld is to be examined from at least two sides. T-butt welds are to be examined also from through

member opposite face (if practicable).

For SMAW welds the separate probes for transmitter and receiver method shall be applied when

surface conditions are detrimental to correct inspection. Tandem technique keeping constant the

inclination angle relevant to the weld seam axis may be applied.

Flaw width shall be evaluated with the 6dB technique, flaw length shall be evaluated with the "half-

value-drop" method.

The use of beam path lengths longer than 200mm is not allowed.






HEN 0000 ST SP 0002 94 of 102

Inspection for acceptance of butt welds over 60mm thick, to which access is limited to one side only,

shall include unrestricted scanning from the surface of the weld. Surface shall be grind to an

appropriate standard for the inspection purpose.

For butt welds with bevel angle between 0° and 10°, and with thickness above 40mm the tandem

technique maybe used.

9.12 Magnetic Particle Inspection Execution

9.12.1 Equipment

Only AC equipment or DC equipment (with current obtained through half wave rectifier) may be used

for testing. Other DC equipment, permanent magnets or equipment which introduces current directly in

the item shall not be used.

The equipment used for magnetic particle testing is to establish a field strength among 2400 Nm (30

Oersted) and 4000 Aim (50 Oersted). The magnetic field adjustment shall be verified by a relevant

instrument. This need not be proven by measurement in case of coil or prod magnetizing, provided the

following requirements are met:

AC electromagnetic yoke is to have a lifting power of at least 4.5 kg at the pole working spacing;

the coil magnetising current is to be chosen depending on the number of turns of the coil. The

ratio between the ampere turns and the diameter of the pipe work piece to be tested is to be 8

to 16 ampere turns per each nun;

AC electromagnetic yoke is to have a lifting power at least 4.5kg with 300rnm prode spacing, for

surface defects only.

for sections with thickness 20mm or more, the prod spacing is within the range 75-200mm with a

current of 5-6A for each millimeter;

for sections with thickness less than 20mm, the current is to be 3.5 to 4.5 A per each mm prod

spacing, with prode spacing within the range 75-200mm.

Prods tipped with lead, or "soft prods" are required.

Equipment and calibration blocks applied to verify the above requirements shall be available to NDT

personnel and to the Company.






HEN 0000 ST SP 0002 95 of 102

9.12.2 Examination

The surface of the parts subjected to test is to be clean and dry, free from any dirt that may interfere

with the examination.

To ensure detection of discontinuities having axes in any direction, the examination is to be performed

with the magnetic field shifted in at least two directions on each area.

Non-fluorescent wet or dry particles are to provide adequate contrast with the background of the

surface being examined. Surface painting shall be used to improve the detection of flaws: white

background paint is preferred.

Magnetic particle examination is not to be performed on parts with surface temperature exceeding

300°C. Wet magnetic particle examination is not to be performed on parts with surface temperature

exceeding 60°C. Care is to be taken to avoid local heating of the test surface.

All prod burns shall be ground out and PT.

Demagnetization shall be provided, when necessary.

9.12.3 Magnetic Fluorescent Particles

This control type shall be done in a darkened room using an ultraviolet radiation light with wavelength

within the range 3200/3800 Angstrom.

Before starting the testing the operator shall remain for 5 minutes to accustom his eyes to low

luminosity. Glasses and contact lens shall not be photosensitive. Before light intensity measurement, it

is necessary to wait 5 minutes for a correct heating and for a correct operation. Ultraviolet radiation

light shall be measured by a particular instrument.

There shall be 800 microwatt/cm2 on the examined surface. Ultraviolet radiation light intensity shall be

measured each 8 hour or whatever the working position is changed.

Wet particles shall be applied on smooth welding surface only.






HEN 0000 ST SP 0002 96 of 102

9.13 Standards of Acceptability

Any weld imperfection that prevents the sizing of, or may prevent the detection of, a weld flaw is itself a

flaw and shall be repaired.

Cracks and lamellar tears found by any of the NOT methods are not admitted in any case and for any

weld classes. All this type of discontinuities shall be inspected to find out the originating cause.

All detected defects that are higher than the following acceptability limits shall be repaired, the weld

restored and a new NDT inspection carried out all over the interested area

9.13.1 Visual Inspection Acceptance Standard

All the outside and inside welds whenever accessible shall be visually inspected. Abutting porosities,

gas cavities, and slag inclusions are to be repaired.

Acceptable undercuts are as follows:

Table 9.3 – Acceptable Undercuts

Weld Classes a b, c d e

Depth (mm) 0.25 0.5 0.5 1

Length (mm) intermittent 10 20 40

9.13.2 RT Acceptance Standard

Flaws on films appearing to meet the acceptance standards limits, but having darkness density giving

a doubt on their depth shall be re examined with UT technique.

The lengths of acceptable volumetric flaws are as follows:






HEN 0000 ST SP 0002 97 of 102

Table 9.4 – Acceptable Flaws

Defect Type a, b c d

Gas Cavities t/3 or 6mm t/3 or 6mm t/3 or 6mm

Linear Porosity individual

cumulative 0.75t 1.5t

3t

12t or 150mm

Slag Inclusions individual

cumulative

1.5t or 6mm

t or 20mm

1.5t or 6mm

2t or 30mm

6mm

2.5t or 60mm

Lack of fusion individual

cumulative Not admitted Not admitted

10mm

1.5t over 12t

Incomplete Root penetration

Individual cumulative Not admitted Not admitted

10mm

1.5t over 12t

Two gas cavities are treated like a linear porosity when the distance between them is less than 6 times

the diameter of the biggest porosity.

The lack of fusion and incomplete penetration acceptance standard for weld class "d" may be applied

to longitudinal double welds class "b, c" as diagonals, deck beams and bracings. All other elements as

nodes, padeyes, buoyancy tanks and their supports are excluded.

9.13.3 UT Acceptance Standard

Any flaw from which echo height exceeds the DAC by 6db shall be repaired and re-examined,

regardless of size.

All flaws classified as planar, like cracks or lamellar tears, shall be repaired whichever is their echo

height.

All echoes that exceed 50% DAC shall be classified and evaluated in size, in accordance with table

9.5.

All transverse defects are to be regarded as defects requiring repair. This requirement does not apply,

where indication can be unequivocally correlated to longitudinal defects.






HEN 0000 ST SP 0002 98 of 102

The lengths of acceptable volumetric flaws are as follows:

Table 9.5 – Nonplanar Acceptable Flaws

Maximum HD and DAC a, b c d

HD > DAC (100%) 10mm 30mm 40mm

HD > DAC/2 (50%) 20mm 45mm 60mm

HD = maximum amplitude defect echo.

Planar defects, clearly detected as lack of fusion and incomplete root penetration may be accepted for

weld class “d” as per Table 9.6

Table 9.6 – Flaw Acceptability for Weld Class “b, c, d”

Flaw Type Depth

(mm)

Length

(mm)

Max

Individual

Length

Cumulative

Lack of fusion 1.5 t/2 10mm 1.5t over 12t

Incomplete root

penetration 1.5 1.5t 10mm 1.5t over 12t

The lack of fusion and incomplete penetration acceptance standard for weld class "d" may be applied

to longitudinal double welds class "b, c" in diagonals, deck beams and bracings. All other elements as

nodes, padeyes, buoyancy tanks and their supports are excluded.

Two gas cavities are treated like a linear porosity when the distance between them is less than 6 times

the diameter of the biggest porosity.

9.13.4 MT Acceptance Standard

Detected rounded indications shall be classified as elliptical shape if the length is equal to or less than

three times the width, or as circular shape in other cases. Linear indications are the remainders.






HEN 0000 ST SP 0002 99 of 102

All surfaces to be examined shall be free from linear and rounded indications caused by weld defect,

not weld geometry, having the limits indicated below:

linear indications are not acceptable whichever their dimensions;

acceptable rounded indications shall not be greater than 4nnn, and there shall not be more than

three indications in line, separated by 1.5mm or less from edge to edge.

9.14 Reports

Operator shall formalize, in the following 24 hours after test completion, the testing results.

The report is to indicate if the weld quality meets the acceptance standard limits of this specification,

and indicate the flaws to be repaired.

The minimum requirements shown in a NDT report shall be the following:

procedure qualification informations;

weld identification number;

sketch of the welded joint and probable flaw location;

flaw description and dimensions;

repair flaws;

any remark.

The report shall clearly show the type of flaw detected (i.e. lack of fusion, incomplete penetration,

porosity and slag) including a repairing flaws location sketch from a particular point choosen as

reference.

9.14.1 RT Reports

The report shall show, beyond general requirements, the following:

film identification number;

film location.






HEN 0000 ST SP 0002 100 of 102

9.14.2 UT Reports


planar and not planar flaw evaluation.

9.14.3 MT Reports


tested surface conditions;

black light intensity;

powder and solvent types used.






HEN 0000 ST SP 0002 101 of 102

10. TESTING OF FIELD INSTALLED COMPONENTS

10.1 Preassembly Testing

When complex assembly items shall be joined offshore, Contractor shall carry out a yard assembly test

in order to verify the correct fit.

Handrail sections or other similar items shall be stamped or metal tagged so that it is possible easily to

restore their exact position during offshore assembly.

Items such as bolt or pin shall be assembled, fitted and welded so that the connection can be

easily installed or removed.

10.2 Hydraulic and Pneumatic Testing

All equipment, components and piping systems shall be tested both by pressure test and in working

conditions, before the load out. Testing shall be done according to relevant line service conditions.

Hydraulic and pneumatic tests are required.

Pressure testing shall be done in conditions of minimum temperature variation as per applicable piping

specification. Pressure shall be maintained at least for one hour.

Flooding values shall be hydrotested to detect leaks either from body or trim, and to verify for their

smooth and free operability.

The leak test shall be done by hydrotest at the maximum working pressure. Reachrods and flooding

valves, when present, operability shall be tested while flooding lines are under pressure.

Flooding valves are to be lubricated and checked before load out to ensure that they are in the closed

position, and that protective caps or other obstructions are not present that would prevent proper valve

operation.






HEN 0000 ST SP 0002 102 of 102

10.3 Testing of Packers System

10.3.1 Testing of Line

All air lines shall be isolated from the grout packers, to prevent damage to grout packers, before this

testing to be done prior to load out.

Test pressure shall be 40 bars for one hour. There shall be no pressure drop and no leaks. After

testing of all lines, they shall be completely drained, dried and re connected to the grout packers.

10.3.2 Testing of Packers

When packers are already inside the barrels, the purchaser shall give a certification relevant to the

acceptance test. Contractor shall apply purchaser requirements for acceptance test when previous

certification is not available.

Documents

HEN-0000-ST-SP-0002