44974-09_ETS - 21 Materials and Fabrication Topside Structures

Document no. 44974-09, case 10/4054 - ETS-21 v. 2

Offshore Substation

Materials and Fabrication of Steel for Topside and

Sub-Structure

ETS-21 Rev. 2

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Document nr. 44974-09, case 10/4054 - ETS-21 v. 2

Revision survey

Document title Materials and Fabrication of Steel for Topside and Sub-Structures.

Document no. 44974-09

Target group Fabrications Contractors and Designer for Offshore substations.

Revision Document status

Writer Reviewer Approver

Init Date Init Date Init Date

1 Approved N/A 12.10.09 N/A 12.10.09 AGS 12.10.09

2 Approved xomo 22.11.2012 GKY, SVR 10.10.2012 POD 03.12.2012

Minor alterations, type errors, rephrases' etc. where the meaning of the text is left unchanged are not shown.

Document no. 44974-09, case 10/4054 - ETS-21 v. 2

Table of contents

1. Scope ............................................................................................... 1

2. References ....................................................................................... 1 2.1 Codes and Standards ............................................................................ 1 2.2 Energinet.dk Technical Standards........................................................... 3

3. Definitions and abbreviations .......................................................... 3 3.1 Definitions ........................................................................................... 3 3.2 Abbreviations ...................................................................................... 4

4. General ............................................................................................ 5 4.1 Quality and HSE - Project Plans ............................................................. 5 4.2 Structural categories ............................................................................ 5

5. Structural Materials ......................................................................... 5 5.1 General............................................................................................... 5 5.2 Steel Material ...................................................................................... 5

5.2.1 Chemical Properties ...................................................................... 6 5.2.2 Bolting Material ............................................................................ 6 5.2.3 Internal Soundness ....................................................................... 7

5.3 Structural Categories ............................................................................ 7 5.3.1 Material Certificates and Markings ................................................... 8

5.4 Fabrication of Welded Structural Members ............................................... 8 5.5 Standard Tubulars and Sections ............................................................. 8 5.6 Stairs/Handrails for Topside .................................................................. 8 5.7 Stairs and grating materials for Sub-structure ......................................... 8 5.8 Platform Doors. ................................................................................... 9

6. Structural steel dimensions ............................................................. 9 6.1 Tubular dimensions and tolerances ......................................................... 9 6.2 Sections - dimensions and tolerances ..................................................... 9 6.3 Steel plates ....................................................................................... 10 6.4 Rectangular/square hollow sections ...................................................... 10

7. Structural fabrication ..................................................................... 10 7.1 Storage and handling of steel materials ................................................ 10

7.1.1 Identification system ................................................................... 10 7.1.2 Alignment .................................................................................. 11

7.2 Structural sections and plates .............................................................. 11 7.3 Scaffolding hooks ............................................................................... 11 7.4 Bolted connections ............................................................................. 11

7.4.1 Bolts in shear and tension connections .......................................... 12 7.4.2 Friction grip connections .............................................................. 12

7.5 Helidecks .......................................................................................... 12 7.6 Lifting fittings .................................................................................... 12

7.6.1 Definition ................................................................................... 12 7.6.2 Materials and Fabrication ............................................................. 13 7.6.3 Additional Requirements .............................................................. 13

7.7 Finishing of structural steel ................................................................. 14 7.8 Fabrication of non-structural steel and temporary attachments ................ 14


7.8.1 Temporary cut-outs .................................................................... 14 7.8.2 Rat holes (Weld access hole) ........................................................ 14

7.9 Fabrication dimension tolerances ......................................................... 14 7.9.1 Tolerances for linear dimensions ................................................... 15 7.9.2 Tolerances for angular dimensions ................................................ 15 7.9.3 Tolerances for straightness, flatness and parallelism ....................... 15 7.9.4 Section ends .............................................................................. 16 7.9.5 Location of seams ....................................................................... 16 7.9.6 High-low .................................................................................... 17 7.9.7 Plates and grating ....................................................................... 17 7.9.8 Landings and stairways ............................................................... 17 7.9.9 Interface tolerance ...................................................................... 17 7.9.10 Markings Sub-structure. .............................................................. 17

8. Welding .......................................................................................... 17 8.1 Welding processes .............................................................................. 17 8.2 Qualifications of welders and welding operators ..................................... 18

8.2.1 Welding coordinator .................................................................... 18 8.2.2 Welders and operators................................................................. 18 8.2.3 Identification of welder or welding operator .................................... 18 8.2.4 Welder's or operator's record ....................................................... 18 8.2.5 Test for branch connections ......................................................... 19

8.3 Welding procedures ............................................................................ 19 8.3.1 General ..................................................................................... 19 8.3.2 Specific requirements .................................................................. 20 8.3.3 Test of the procedure welds ......................................................... 20

8.4 Production welding ............................................................................. 21 8.4.1 Welding sequences ..................................................................... 21 8.4.2 Weld preparation ........................................................................ 21 8.4.3 Weld execution ........................................................................... 21 8.4.4 Pre-heating ................................................................................ 22 8.4.5 Inter-pass temperature ............................................................... 23 8.4.6 Post weld heat treatment (PWHT) ................................................. 23 8.4.7 Weld repairs ............................................................................... 23 8.4.8 Production testing ....................................................................... 24

9. Non-destructive examination ......................................................... 24 9.1 Extent of examinations ....................................................................... 24 9.2 NDE Qualifications .............................................................................. 25

9.2.1 Examination organisation ............................................................. 25 9.2.2 Examination personnel ................................................................ 25 9.2.3 Procedures ................................................................................. 25

9.3 Execution of NDE ............................................................................... 25 9.4 NDE procedure and acceptance criteria. ................................................ 25

9.4.1 Visual (VT) procedure and acceptance criteria ................................ 25 9.4.2 Magnetic particle (MT) procedure and acceptance criteria ................ 26 9.4.3 Radiographic testing (RT) procedure and acceptance criteria ............ 26 9.4.4 Ultrasonic testing (UT) acceptance criteria ..................................... 26 9.4.5 Liquid Penetrant testing (LP) acceptance criteria ............................. 26

9.5 Execution of NDE, structural fabrication ................................................ 26 9.5.1 General ..................................................................................... 26 9.5.2 Sequence of examination ............................................................. 27 9.5.3 Surface conditions ...................................................................... 27 9.5.4 Random examination................................................................... 27


9.5.5 Extent of examination in case of unacceptable welds ....................... 27

10. Coating .......................................................................................... 28

11. As-built documentation .................................................................. 28 11.1 Deliverables .................................................................................. 29

12. Appendix ........................................................................................ 30

Document no. 44974-09, case 10/4054 - ETS-21 v. 2 1/40

1. Scope

This technical standard specifies the minimum requirements for the materials,

fabrication, testing and inspection of offshore steel structures for topsides and sub-

structures (Jackets) intended for high voltage offshore transformer platforms

(Substations).

This technical standard covers also the main supporting steel structure for helideck

on topside. However, the lattice structure typically integrated under the helidecks

may be preferred by Energinet.dk to be made of aluminium. For aluminium

structures this standard refers to the DNV standard DNV-OS-E401.

This standard may only be departed from if the deviations are approved by

Energinet.dk and certifying agency or if specified on Energinet.dk approved design

drawings.

2. References

The following codes, standards and statutory regulations shall be considered as part

of this technical standard.

2.1 Codes and Standards

All regulations, codes and standards referred to in the present standard shall apply in

the latest revision applicable at the beginning of the project unless noted otherwise.

API 2B Specification for fabricated structural steel pipe

API 5L Specification for line pipe

ASME, Section V Article 7, Magnetic Particle Examination

ASME, Section V Article 9, Visual Examination

ASME, Section IX Qualification standard for welding and brazing procedures,

welders, brazes and welding and brazing operators

AWS D1.1 Structural welding code - steel

BS 7448 Part 1, Specification for fracture mechanics toughness test

DNV-OS-C101 Design of offshore steel structures (LRFD method)

DNV-OS-C401 Fabrication and testing of offshore structures

DNV-OS-E401 Offshore standard, Helicopter Decks


DNV-OS-J201 Offshore Substations for Wind Farms

EN 287-1 Approval Testing of Welders for Fusion Welding.

EN 473 Qualification and certification of NDT personnel. General

principles.

EN 970 Welding – Visual Examination of Fusion Welded Joints.

EN 1011 Recommendations for Arc Welding of Ferritic steels.

EN 1418 Welding personnel – Approval testing of welding personnel for

fully mechanized and automatic welding of metallic materials

EN 10002-1 Metallic Materials - Tensile Testing - Part 1. Method of Test.

EN 10025 Hot Rolled Products of Non-Alloy Structural Steels. Technical

Delivery Conditions.

EN 10225+AC Weld able structural steels for fixed offshore structures –

Technical delivery conditions

EN 10045 Metallic Materials - Charpy Impact Test.

EN 10163-1 to 3 Delivery Requirements for Surface Conditions of Hot Rolled

Steel Plates, Wide Flats and Section.

EN 10164 Steel Flat Products with Specified Through Thickness

Properties. Technical Conditions for Delivery.

EN 10204 Metallic Products - Types of Inspection Documents.

EN 10210 Hot Finished Structural Hollow Sections of Non-Alloy and Fine

Grain Structural Steels.

EN 45004 General Criteria for the Operation of Various Types of Bodies

Performing Inspection.

EN ISO 5817 Welding-Fusion-welded joints in steel, nickel, titanium and

their alloys

EN ISO 13920 Welding – General tolerances for welded constructions –

dimensions for lengths and angles – Shape and position

EN ISO 17025 General Requirements for the Competence of Testing and

Calibration Laboratories

ISO 898 Part 1-6, Mechanical properties of fasteners made of carbon

steel and alloy steel

ISO 1459 Protection against corrosion by hot dip galvanizing

ISO 1461 Hot dip galvanized coatings on fabricated iron and steel articles

– Specifications and test methods

ISO 3690

Welding and allied processes. Determination of hydrogen


content in ferritic arc weld metal

ISO 7090 Plain washers, chamfered. Normal series. Project grade A

ISO 8501 Part 1-2, Preparation of steel substrates before application of

paints and related products. Visual assessment of surface

cleanliness.

ISO 1106 Recommended practice for radiographic Examination of Fusion

Welded Joints.

ISO 2553 Welds - Symbolic Representation on Drawings.

ISO 3452 NDT - penetrant inspection - general principles.

ISO 9606-2 Qualification test of welders – Fusion welding of aluminium and

its alloys

ISO 15614 Specification and qualification of welding procedures for

metallic materials

BL 3-5 Statens Luftfartsvæsen, Bestemmelser om helikopterdæk på

havanlæg

2.2 Energinet.dk Technical Standards

ETS-00

Guideline for Use of Energinet.dk Technical Standards

ETS-24 Weight Monitoring and Weighing

ETS-25 Protective Coating of Steel

EDS-01

EDS-02

Engineering Reports, Drawings and Lists

Requirements for "As-Built" Documentation for Offshore

Substations.

3. Definitions and abbreviations

3.1 Definitions

The following definitions are used in the present standard:

Employer: Energinet.dk

Employer approval: “Employer approval” or similar terms, requires approval in

writing from Energinet.dk or his representative


3.2 Abbreviations

Within this specification the following abbreviations have been used. Abbreviations of

standards and atomic elements are though not covered.

CE: Carbon equivalent calculated according to EN 1011-2

CTOD: Crack tip opening displacement

Dnom: Nominal diameter

ET: Eddy Current

HV: Vickers hardness

IQI: Image quality indicator

+M: Delivery condition : thermo mechanical rolling

MT: Magnetic particle examination/testing

+N : Delivery condition: normalizing rolling

NDE : Non destructive examination

OD: Outer diameter

PT: Liquid penetrant examination

PWHT: Post weld heat treatment

+Q: Delivery condition: quenched and tempered

RT: Radiographic examination/testing

t: Wall thickness

UT: Ultrasonic examination

VT: Visual examination/testing

WPQR: Welding procedure qualification record

WPS: Welding procedure specification


4. General

All fabrication shall be carried out in accordance with agreed procedures and

drawings and shall comply with applicable codes, standards and specifications as

listed in this ETS.

Unless otherwise stated herein, the DNV standards DNV-OS-C401 “Fabrication and

testing of offshore structures” and DNV-OS-C101 “Design of offshore steel structures

(LRFD method)” shall form basis for this standard.

4.1 Quality and HSE - Project Plans

Contractor shall submit a project specific quality plan to Energinet.dk for their review

and approval. The document shall as minimum contain the following information:

Detailed fabrication plan and schedule

Organisation diagram

Manpower plan

Inspection and Test Plan.

Dimension control procedure

Welding preparation details and procedures

NDE procedures

Qualification of NDT operators

Qualification of welders

HSE manual

List of major sub-contractors

4.2 Structural categories

Structural categories for selection of materials and determination of the extent of

inspection shall be in accordance with the relevant section of DNV-OS-C101.

5. Structural Materials

5.1 General

The steel type grades for topside structures shall comply with the requirements listed

in appendix 1A.

The steel type grades for steel Sub-structures shall comply with the requirements

listed in appendix 1B.

5.2 Steel Material

Steel type 2 can replace steel type 1 whereas steel type 4 can replace steel type 3.


Steel types shall be applied in accordance with approved design drawings. The

following table shows typical material selections.

Steel type Structural category

Special Primary Secondary

ST1 x x

ST2 x x

ST3 x x

ST4 x x

ST5 x

Table 5-1 – Material selection

Type 1-4 steel are used where charpy impact tests and CTOD testing is required.

Type 2 and 4 steel shall be used where loads in thickness direction occur for

thickness of 25 mm and above.

5.2.1 Chemical Properties

Where galvanising has been required the content of Silicon (Si) in the steel shall be

minimum 0.15% and maximum 0.40%. The desirable content of Silicon is between

0.15% and 0.25%. Steel type 3 and 4 shall not be galvanised.

5.2.2 Bolting Material

All bolts and nuts shall be delivered and marked according to EN 20898-1 class 8.8

and EN 20898-2 class 8 respectively unless otherwise specified on design drawings.

All bolts and nuts shall be hexagon type with ISO metric thread.

Bolts and nuts with diameter 10 mm or more shall be hot dip galvanised according to

ISO 1461 class E and ISO 1459.

Bolts with diameter less than 10 mm shall be made of stainless steel, ISO 3506

grade A4-70, unless otherwise specified on design drawings. Where used for

assembling carbon steel, insulation washers to be used.

For bolting material used below LAT +4 m, a waxy rust proofing compound shall be

applied. Bolts and nuts for sub-sea installation (below LAT - 2 m) shall be PTFE

(Teflon) coated.

Washers shall be according to ISO 7090 quality class HV 200. The diameter of

washer holes to be 1 mm greater than bolt size for bolts up to 18 mm and 1.5 mm

for larger bolts. Hardened washers must be used for friction grip bolts.

Bolt, nuts and washers to be delivered with 2.2 certificate according to EN 10204.

For assembling stainless steel parts, only stainless steel bolts shall be used.


Split pins materials shall be stainless steel, ISO 3506 grade A4-70.

5.2.3 Internal Soundness

For internal soundness, requirements stipulated in EN 10025-X option 6, 7 and 8

shall apply.

5.3 Structural Categories

Table 5-2 Structural Classification – typical applications

Structural category for Topside Structures


All Pad-eyes/lifting trunnion Supports for main cables

& Hang-off's

Ladders

Main tubular columns Deck beams in grid lines Handrails

Crane pedestal Bracing members Stairs

Support structure for

helideck

Sea-fastening Cable ladder supports

(minor cables)

Support beams/structure for

main transformer

Deck plates Grating

Secondary deck beams Supports for minor

equipment (e.g.

antennas & satellite

discs)

Nodes in main tubular

Cones in main tubular

Pipe supports

Structural category for Sub-structures (Jacket)


Pad-eyes/lifting trunnion Mudmat Ladders

Jacket legs and braces J-tubes Handrails

Piles and pile sleeves Caissons Stairs

Boat landing (integrated) Boat landing Grating


5.3.1 Material Certificates and Markings

Steel materials shall be delivered with inspection certificates according to EN 10204

Structural category: Material Certificate:

Special 3.2

Primary 3.1

Secondary 2.2

Table 5-3 Material certificates according to EN 10204

Where traceability is required all steel material shall be marked according to relevant

standards listed in appendix 1.

If traceability of a material is not required the material shall as minimum be marked

with material grade.

Material that cannot be identified as outlined above shall be rejected.

5.4 Fabrication of Welded Structural Members

Welded tubulars shall be fabricated in accordance with API 2B. Mechanical tests for

tubulars must be carried out in the finished configuration.

Welded profiles (sections) shall be in accordance with the requirements stipulated in

appendix 1.

5.5 Standard Tubulars and Sections

Seamless tubulars shall be manufactured in accordance with API 5L unless otherwise

specified. Seamless tubulars shall be inspected in accordance with SR4.

Rolled profiles (Sections) shall be in accordance with the requirements stipulated in

appendix 1.

5.6 Stairs/Handrails for Topside

See standard drawings ref. appendix 2, 3, 4 and 5.

5.7 Stairs and grating materials for Sub-structure

Materials for grating and steps for stairs shall be GRP. Grating shall be as "Fibeline

Moulded Grating 50x50", with anti-slip surface.


Stair treads to as "Fiberline Moulded Grating Steps".

Min 4 pcs fixations for the GRP grating is required per square meter and not less

than 3 for each grating piece. The fasteners shall be of stainless steel AISI 316

quality.

Grating fasteners shall not be installed onto closed sections (e.g RHS e.t.c.).

5.8 Platform Doors.

A door schedule shall be developed as part of the design and construction. It shall be

continuously updated throughout the design and construction phase, until all

required information is specified prior to procurement.

All external and internal doors shall be designed and fabricated in accordance with

NORSOK C-002 with respect to: Materials, fire rating and hardware.

All doors on the substation shall be of stainless steel AISI 316L with a suitable

painted surface after supplier's recommendation.

Gutter shall be installed above all external doors - made of suitable angel bar,

welded to wall plate. Slope 1:100 to both sides from middle of gutter.

6. Structural steel dimensions

6.1 Tubular dimensions and tolerances

Tubulars are to fulfil the following dimensional tolerances:

OD < 406 mm tolerances according to API 5L

OD 406 mm tolerances according to API 2B

As a supplementary requirement the minimum wall thickness must be as specified,

i.e. no negative tolerance allowed.

All tubulars shall meet the straightness requirements for API-2B.

Out-of-roundness shall be limited to the lesser of:

OD(max.) - OD(min.) 1% of Dnom

OD(max.) - OD(min.) max{6 mm, (t mm)/10}

Additionally, the local out-of-roundness shall be measured using a 20 gauge. This

shall not depart from the theoretical shape by more than 10% of wall thickness.

6.2 Sections - dimensions and tolerances

Mechanical tests for profiles must be carried out in the finished configuration.


Profiles shall meet the dimensional tolerance requirements of applicable standard as

per Appendix 1, except for length tolerance, which shall be in accordance with EN

ISO 13920. Maximum straightness deviation shall not exceed 1/1000 of the length

and maximum 10 mm for lengths greater than 10 m.

6.3 Steel plates

Mechanical tests for steel plates must be carried out in the finished configuration.

Steel plates shall meet the dimensional tolerance requirements of EN 10225 and EN

10025.

6.4 Rectangular/square hollow sections

Mechanical tests for rectangular/square hollow sections must be carried out in the

finished configuration.

Rectangular/square hollow sections shall meet the dimensional tolerance

requirements of EN 10225 and EN 10025.

For primary steel only seamless hollow sections are allowed.

7. Structural fabrication

All fabrication shall be carried out in accordance with agreed procedures, approved

design drawings and shall comply with applicable codes and standards listed in said

ETS.

7.1 Storage and handling of steel materials

When materials are received contractor shall inspect them in order to ensure that:

a) Marking of materials complies with the documentation

b) Documentation complies with the latest revision of the relevant specification

c) Materials are not damaged during transportation

The inspection shall be documented in a materials receiving inspection report

Storage of material or subassemblies shall be above ground level, ensuring that it is

kept free of dirt, grease, paint and other alien materials. All materials and

subassemblies shall be handled and stored in a way that will ensure that the material

is not damaged.

All materials shall be traceable to the Energinet.dk contract in question.

7.1.1 Identification system

Before starting of fabrication contractor shall establish a numbering system to

identify each weld and structural member in order to eliminate conflicting or

duplicating of identification systems.


For structures in the structural categories Special and Primary, the numbering

system shall ensure traceability for all welds and materials during all stages of

fabrication and in the as-built documentation.

For structures in the structural category Secondary, the numbering system shall

ensure traceability during all stages of fabrication.

7.1.2 Alignment

Wherever practical, clamps, magnets holding devices or other setting-up fixtures

shall be used in assembling parts of the structures in order to minimise tack welding

in the weld groove.

If fit-up clamps cannot be used spacer strips shall be used in order to ensure the

specified root gap prior to tack welding.

7.2 Structural sections and plates

All welds shall be continuous (closed welds). A minimum of 4 mm throat thickness

seal weld shall be applied where structural welds are not required.

Beam sections with identical cross sections may be spliced. Minimum distance

between 2 splices shall be 1200 mm.

The splices cannot be located within the first 1/8 or the middle 1/4 of a section

7.3 Scaffolding hooks

Unless otherwise noted on design drawings, scaffolding hooks are to be installed

below all decks in a 2m x 2m grid.

7.4 Bolted connections

Procedures for the bolt tightening shall be prepared prior to the work and records of

the tensioning shall be maintained during the work.

If bolt pre-stressing is required according to the design drawings hydraulic pulling

pre-stress tool shall be used unless otherwise agreed with Energinet.dk. Calibration

of pre-stressing tools shall be documented.

Bolt heads and nuts shall rest squarely within 3 against the base material, and bolts

shall be of lengths that will extent entirely through and up to a maximum of 6 mm

beyond the nuts.

No welding is allowed on bolt items.

Counter nuts shall secure all nuts unless otherwise noted.

Washers shall be used at both bolt head and nut except when tensioning equipment

is used. Spring washers are not allowed in structural members.

The galvanized surface for the fasteners must remain intact after tensioning.


All holes shall be drilled and reamed as necessary prior to application of protective

coating. Outside burrs resulting from drilling or reaming operations shall be removed

with a tool making a 2 mm bevel.

Grease shall always be applied when using torque-tensioning technique. The grease

shall be of the non-corrosive type and must not contain Sulphur (e.g. MoS2).

7.4.1 Bolts in shear and tension connections

Bolts in structural members from M12 mm and up shall be pre-stressed to 50% of

yield strength unless otherwise specified.

7.4.2 Friction grip connections

Bolts shall be pre-stressed and documented as specified on drawings.

Enlarging of holes for high stress bolts shall be carried out by reaming only. Holes

shall be clean-cut without torn or ragged edges. Outside burrs resulting from drilling

or reaming operations shall be removed with a tool making a 2 mm bevel.

7.5 Helidecks

The main supporting steel structure for a helideck on the topside structure is covered

by this standard.

The lattice structure typically integrated under the helidecks shall be made of

seawater resistant aluminium unless otherwise stated. For classification, reference is

made to ‘Offshore Standard, Helicopter Decks DNV-OS-E401.

The helidecks shall be designed and marked to comply with ‘Statens Luftfartsvæsen’

regulation BL 3-5.

Walkways, railings and stairs from the decks to the topside shall be included and are

also to be designed in seawater-resistant aluminium, if assembled with aluminium

helideck.

7.6 Lifting fittings

Lifting fittings are defined as lifting lugs, lifting trunnion and pad eyes.

For lifting fittings, the additional requirements presented in this section must be

fulfilled.

7.6.1 Definition

Lifting fitting loads are defined as follows:

Low load: Max 10 tonnes unit load


Normal load: Max 50 tonnes unit load

High load: Above 50 tonnes unit load

Unit load is the total current weight of the structure to be lifted.

7.6.2 Materials and Fabrication

All materials for lifting fittings shall be of steel type 3 special steel.

Welding of lifting fittings shall be of full penetration type welds unless noted

otherwise on the design drawings.

All plates for lifting fittings shall be examined 100% according to EN 10160 Class S1

Pinholes in pad eyes shall be machined. If cheek plates are fitted the machining of

the hole shall be carried out after welding of the cheek plates.

Full dimensional and orientation checks of all lifting fittings shall be made upon

completion. Complete non-destructive re-testing by means of MT and UT shall be

carried out on all lifting fittings after each lift or when load has been applied.

The lifting fittings shall be completed with a topcoat RAL 1004 (yellow) and marked

with SWL in black letters.

7.6.3 Additional Requirements

The following additional requirements apply for “high load” and “normal load” lifting

fittings:

In pad eye plates, the final rolling direction shall be indicated by hard stamping

Lifting direction shall be in the final rolling direction

For “high load” the following further requirements apply:

Full mechanical and chemical re-test shall be performed

Charpy impact testing shall be performed transverse to the final rolling direction

Tensile test pieces shall be tested transverse to the final rolling direction

Where “high load” lifting fittings are welded directly onto a structure, the

structural members shall have documented through thickness properties (i.e.

type 2 or 4 steel). Otherwise, the pad eye shall be sliced into the structure

For “normal load” and “low load” the following additional requirements apply:

A chemical re-test shall be performed to document the traceability between the

material and the original certificate.


For lifting fittings in “low load”, the chemical re-test may be avoided if an

additional material factor of 1.5 is used in the design.

7.7 Finishing of structural steel

All temporary attachments for scaffolding, temporary bracing etc. shall be removed

by cutting not closer than 3 mm to the structure and then ground flushed with the

surface. Subsequently, 100% MT shall be performed. Minor surface defects on

primary steel shall be ground to sound metal, 100% magnetic particle inspected,

weld repaired, if necessary, and magnetic particle re-inspected.

7.8 Fabrication of non-structural steel and temporary attachments

When welding non-structural and temporary attachments to primary structural

components a minimum clearance of 200 mm between any attachments weld toe

and any structural component weld toe shall be kept.

All temporary welds shall require a minimum of two weld passes. The last pass (es)

shall be deposited against the temporary part.

7.8.1 Temporary cut-outs

When temporary cut-outs are necessary they shall be prepared with the same care

as for permanent cut-outs including carefully rounded corners.

7.8.2 Rat holes (Weld access hole)

Rat holes shall only be used where absolutely required and they shall then have a

radius of 30 mm. The welds shall be continued through the rat hole.

Rat holes shall be sealed with closure plates fillet welded to the structure after

completion of NDE on the main steel.

7.9 Fabrication dimension tolerances

The fabrication dimensional tolerances for welded sections shall be in accordance

with DNV-OS-C401.

In addition to the requirements in DNV-OS-C401, the tolerances for linear and

angular dimensions and straightness shall be as stated in the following tables.


7.9.1 Tolerances for linear dimensions

Tolerances for linear dimensions shall be in accordance with EN ISO 13920, Class B

and C.

Range of nominal length in mm

Tolerance Class

(Structural

Category)

< 3

0

<120

<400

<1000

<2000

<4000

<8000

<12000

<16000

≤20000

> 2

0000

Tolerances in mm

B (Special)

±1 ±2 ±2 ±3 ±4 ±6 ±8 ±10 ±12 ±14 ±16

B (Primary)

±1 ±2 ±2 ±3 ±4 ±6 ±8 ±10 ±12 ±14 ±16

C (Secondary) ±1 ±3 ±4 ±6 ±8 ±11 ±14 ±18 ±21 ±24 ±27

Table 7-1 – Tolerances for linear dimensions

7.9.2 Tolerances for angular dimensions

Tolerances for angular dimensions shall be in accordance with EN ISO 13920, Class B

and C. The length of the shorter angle leg as specified in the following table shall be

used to determine which tolerances are to apply.

Range of nominal sizes l in mm (l=length of shorter leg)

Tolerance Class

(Structural

Category)

<400

<1000

>1000

Angular tolerances in degrees

B (Special)

±0.8 ±0.5 ±0.3

B (Primary)

±0.8 ±0.5 ±0.3

C (Secondary)

±1.0 ±0.8 ±0.5

Table 7-2 – Tolerances for angular dimensions

7.9.3 Tolerances for straightness, flatness and parallelism

Tolerances for straightness, flatness and parallelism shall be in accordance with EN

ISO 13920, Class E. The tolerances as specified in the following table apply for both

the overall dimensions of a weldment, a welding assembly or a welded structure.


Range of nominal length in mm

Tolerance Class

(Structural

Category)

< 1

20

<400

<1000

<2000

<4000

<8000

<12000

<16000

<20000

<20000

Tolerances in mm

E (Special)

±0,5 ±1 ±1,5 ±2 ±3 ±4 ±5 ±6 ±7 ±8

E (Primary)

±0,5 ±1 ±1,5 ±2 ±3 ±4 ±5 ±6 ±7 ±8

F (Secondary)

±1 ±1,5 ±3 ±4,5 ±6 ±8 ±10 ±12 ±14 ±16

Table 7-3 – Tolerances for straightness, flatness and parallelism

The dimensions given in the drawings are applicable at a temperature of +10C.

Corrections must be performed if the manufacturing temperature differs from this,

by more than 10 C.

Contractor shall submit construction drawings marked up to as-built status and

indicate as-built interface dimensions, which could affect offshore operations.

7.9.4 Section ends

The ends of sections cut perpendicular to the longitudinal axis shall be perpendicular

to the axis with a maximum deviation of 3 mm, unless otherwise indicated on the

drawings.

7.9.5 Location of seams

Minimum distance between circumferential seams in tubular shall be 1200 mm

unless shown otherwise on the drawings. Length of node stubs shall not be less than

the outside diameter or 610 mm whichever is the strictest.

Circumferential seams shall be avoided within node stubs.

Longitudinal seams shall preferably be 180 degrees offset wherever practical and

shall not be less than 15 degrees offset.

The longitudinal seams on node chord cans shall be located at a minimum radial

distance of 75 mm from the edge of any brace to chord welds.


7.9.6 High-low

High-low, defined as a condition where tubular surfaces are misaligned, can be

accepted provided the misalignment does not exceed 3 mm for single sided welding

and 6 mm for double sided welding. The root of adjacent tubular joints shall be

completely tied-in (bonded) by weld metal and smooth transition shall be assured.

The maximum acceptable misalignment as specified in EN ISO 5817.

7.9.7 Plates and grating

Grating shall be flat and without visible warping. Maximum allowable warping is 2

mm. Slope of plates and grating shall be maximum ±6 mm/3 m.

7.9.8 Landings and stairways

Horizontal and vertical location of landings and stairways shall not deviate from

theoretical measures on design drawings with more than 10 mm.

7.9.9 Interface tolerance

Interface checks between Topside and Sub-structure shall be subject for detailed

review and scrutiny by the Contractor.

The result of said review shall be subject for approval by Energinet.dk.

7.9.10 Markings Sub-structure.

Water level figures shall be painted on the jacket legs, oriented 450 with respect to

the gridlines.

The water level marking shall consist of a circumferential marking line at every

meter, start and end elevation to be agreed. The lines shall be black on yellow

background. Line width shall be 100 mm for El (+) 0.000, and 50 mm for all other

elevations.

The figures shall be min 500 mm high, painted black on yellow background.

The jacket leg id number shall be painted on 3 locations around the circumference

with 400 mm high identification letters at agreed elevation. The id's letter/figures

shall be black on rectangular white background.

8. Welding

The welding workshop shall have a quality management system in accordance with

ISO 9001, ISO 3834 series or equivalent standard.

An organisation chart, which as a minimum shall include the names of the

responsible manager, quality responsible, welding and NDE coordinator, and NDE

level III, shall be available.

8.1 Welding processes

Welding may be performed with the following processes unless otherwise specified:


Metal-arc welding with covered electrode

Self-shielded tubular-cored arc welding

Submerged arc welding

Metal inert gas welding (MIG)

Metal active gas welding (MAG)

Tubular-cored Metal arc welding

Tungsten inert gas arc welding (TIG)

Plasma arc welding

Other welding processes shall be agreed with Energinet.dk prior to fabrication.

8.2 Qualifications of welders and welding operators

8.2.1 Welding coordinator

The workshop shall have one welding coordinator whereby welding personnel can be

supplied with the necessary procedure specifications and work instructions to ensure

that the work is correctly executed and managed.

The welding coordinator shall be certified European Welding Engineer (EWE) or

similar.

8.2.2 Welders and operators

All welders and operators shall be experienced and qualified in the workshop in

accordance with the requirements of EN 287 series, ISO 9606, ASME IX or

ANSI/AWS D1.1 for welders and EN 1418 for operators or equivalent standards

approved by Energinet.dk.

The welder performance qualification test shall be carried out in accordance with a

qualified welding procedure specification (WPS).

8.2.3 Identification of welder or welding operator

Welder Performance Qualification (WPQ) sheets with photograph shall be used for

documentation purpose.

Each qualified welder or welding operator shall be assigned a symbol, which always

shall be visible during welding. The welder or welding operator shall mark his welds

with his symbol. Welder's symbol shall be stated in NDE-reports and as-built

documentation for high and normal safety class structure.

8.2.4 Welder's or operator's record

A record shall be kept of the welder’s or welding operator’s symbols and be available

at all times.

A record of the welders or welding operators work performed during the last 12

months shall be available to Energinet.dk at all times.


8.2.5 Test for branch connections

Tests of welders for branch connections (Y-joints) are given below for the structural

categories Special and Primary.

‘Y’ joint welder's qualification shall be required for branch connections (Y and K

connections between tubulars or tubulars welded to plates, branch outside diameter

above 150 mm) in addition to the welding test piece positions either PC and PF or to

H-L045/G6 qualification.

The test weld is a Y-joint between a vertical plate and a tube (branch) with a min.

diameter of 200 mm and with an inclination of 35. Groove geometry shall be as

specified in the relevant welding procedure qualification record. The plate thickness

shall be at least 15 mm and shall have a minimum length and width equal to two

times branch outside diameter. The thickness of the branch shall be at least 15 mm.

Free end of the branch shall be oriented downwards in relation to vertical and be

covered by a temporary plate during welding.

The welding parameters shall be in accordance with a qualified welding procedure.

No back welding is permitted.

All test welds shall be 100% ultrasonic tested in accordance with section 8.0

From the test weld three macro sections taken from 6 o’clock, 9 o’clock and 12

o’clock shall be made.

Each macro section shall be examined and found to be acceptable to ASME code

section VIII.

8.3 Welding procedures

8.3.1 General

Welding Procedure Qualification Records (WPQR's) shall reflect the production and

shall be performed in accordance with EN ISO 15614-1 or ASME IX, unless otherwise

stated in this section.

WPS (Welding Procedure Specification) shall be prepared in accordance with EN-288-

1, AWS D1.1 or an equivalent standard approved by Energinet.dk

WPS's inclusive copy of reference WPQR shall be issued to Energinet.dk for approval

prior to commencement of welding.

The material used in the WPQR shall be made on project materials only.

Already established, sufficiently tested and documented procedures may however,

be acceptable, if approved by Energinet.dk prior commencement of production.


Test body shall be acceptable to Energinet.dk. Test bodies will be approved if

accredited by national authorities according to EN 45004 for certification of welding

procedures according to EN ISO 15614-1 series or ASME IX.

The validity of a qualified welding procedure is restricted to the workshop specifying

the procedure and performing the procedure welding. Workshops or workshop

branches under the same technical management and working in accordance with the

same QA-programme and procedures are considered as one workshop.

For welding of structural category Secondary only approved WPS’ are required.

8.3.2 Specific requirements

The degree of cold deformation of special and primary structural elements shall be

less than 5%. If the deformation exceeds 5%, either heat treatment or strain ageing

tests shall be carried out according to agreed procedure.

The carbon equivalent (CE) of the production material shall not exceed that of the

steel used for the WPQR by more than 0.03%.

Deviations from the specific requirements shall require a new welding procedure

test.

8.3.3 Test of the procedure welds

Examinations shall be performed not earlier than 48 hours after completion of the weld.

CTOD testing (Fracture mechanics testing) shall be performed in accordance with the requirements stipulated in DNV-OS-C101. CTOD test shall be carried out according to BS 7448 Part 2 (with detailed requirements as given in DNV-OS-C401). Hydrogen removal treatment is not allowed without prior approval from

Energinet.dk. CTOD results shall be calculated using appropriate values of yield stresses.

Charpy-V Impact test: The following minimum values shall apply:

Steel type Steel type 1 - 4 Steel type 5

Charpy-V impact

values (J) 50 27

Temperature (oC) -40 -20

Table 8-1 Minimum average Charpy-V notch impact test value


8.4 Production welding

8.4.1 Welding sequences

Contractor shall develop erection sequences, which shall include welding sequences

to control fabrication tolerances within the specified limits and prevent the build-up

of excessive internal stresses in the structure.

8.4.2 Weld preparation

Contractor shall establish shielding to protect each welding site from rain, snow and

wind. No welding shall be carried out when the surface is damp, wet or icy'.

Preparation and welding of materials shall be in accordance with the qualified

welding procedures.

Welds shall be made from both sides whenever possible. Single sided butt welds

shown on the design drawings may be executed from the other side to suit

fabrication.

8.4.3 Weld execution

Workmanship

Clean, sound metal shall be provided as a base for weld metal deposition; this may

necessitate grinding or gouging followed by grinding at a depth of min. 2 mm.

Double-sided welds shall be back-gouged and ground or ground to sound metal

before the second side is welded. The resulting excavation shall have a profile

suitable for welding.

Each run of weld metal shall be thoroughly cleaned of flux, spatter and slag before

depositing the next weld run. If necessary, crater cracks shall be removed prior to

deposition the next weld run.

Arc strikes

Arc strikes outside the welding groove are not permitted. Repair will be grinding in

accordance with section 7.7. Suitable NDE methods shall be used to search for

cracks.

Tack welds

Tack welds shall be of a minimum length of four times the base metal thickness or

100 mm, which is lesser, and carried out according to a qualified welding procedure.

Tack welds shall have adequate cross section to prevent cracking.

Tack welds that form part of the completed weld shall be cleansed, crack detected

and completely fused with the root run.

Cracked tack welds shall be completely removed by grinding and shall not be

incorporated into the finished weld. After removal, the parent material shall be


magnetic particle or liquid penetrant examined to ensure that crack propagation

from the tack weld into the parent material has not occurred.

Arc/air gouging

All arc/air-gouged surfaces shall be dressed to bright clean metal by grinding at an

additional depth of min. 2 mm. The gouged/grounded profile shall be suitable for

welding with the applicable process.

Specific care shall be taken that the arc is not struck before full airflow is

established.

Energinet.dk shall approve the procedure prior to gouging.

Weld interruption

Welding shall not be discontinued before 25% or 3 passes of the weld thickness is

complete, whichever is more stringent. At this stage the weld profile should be

concave particularly at the weld material/parent plate interface.

Branch connections

Qualified T-joint welders shall be used for the first 25% or 3 passes of the weld,

whichever is more stringent. For the other passes welders qualified in the H-L045

position may by used.

Joint preparation and cleaning

Wire brushing and grinding of materials shall be performed using silicon carbide

grinding wheels and steel wire brushes, which have not been used previously on

another type of material.

Backing

Permanent backing is not permitted unless accepted by Energinet.dk prior to

fabrication.

8.4.4 Pre-heating

Pre-heating shall be carried out by electrical resistance, induction equipment or by

use of gas burners specifically made and shaped for this type of operation. Cutting

torches are not allowed for pre-heating.

The minimum pre-heat temperature shall be the higher of the following:

a) The temperature specified in the relevant approved welding procedure.

b) Work pieces shall be heated to ensure a minimum temperature of 25 C and

dryness.

c) The minimum temperature shall be calculated according to EN 1011

The pre-heat temperature shall be established for a distance of at least 75 mm on

either side of the weld and through the wall thickness prior to welding. Pre-heating


shall be maintained over the full length of the joint or min. 1 m ahead of the arc and

throughout the whole welding operation.

The temperature measurement for pre-heating shall be thermocouples or

temperature-indicating crayons.

8.4.5 Inter-pass temperature

The minimum inter-pass temperature shall be at least equal to the pre-heat

temperature and shall not exceed 250 C.

8.4.6 Post weld heat treatment (PWHT)

Post weld heat treatment (PWHT) shall always be performed according to the same

approved WPQR as the welding has been based on.

Due to requirements from the design code PWHT shall be performed with electric

resistance, induction equipment or in a fixed furnace, when applicable. The

temperature shall be monitored by means of thermocouples. Sufficient amount of

thermocouples shall be used to cover the area being PWHT adequately.

PWHT shall be determined in accordance with DNV-OS-C401.

The weld shall be PWHT and the surrounding area shall be covered with insulation

material covering minimum 500 mm on each side of the weld. The insulation

material shall not be removed before the temperature is below 250 C. For tubular

the open ends shall be covered to avoid draught inside the tubular during the heat

treatment.

PWHT temperature/time charts shall be clearly identified and retained. The

information shall be accurately transferred from the charts to thermal history graphs.

8.4.7 Weld repairs

All corrective work consisting of removal of defects and deposition of repair welds

shall be in accordance with the qualified repair welding procedure. Alternatively, the

deposition of repair weld shall be in accordance with a welding procedure qualified

for the original weld.

Removal of defective areas shall be by machining, grinding, chipping or arc/air

gouging followed by grinding. The resulting excavation shall be clean, free from scale

and have a contour to permit ease in repair welding. MT or PT shall assure defect

removal.

The mechanical properties of repair weld shall satisfy the minimum specified

properties of the steel in question.

Repairs and modifications shall be identified and documented.


Second weld repair requires Energinet.dk approval.

Frequent repairs shall result in increased NDE according to DNV-OS-C401, Section 3

– B400.

8.4.8 Production testing

Energinet.dk reserves the right to select test welds for production tests directly from

the production welds.

The testing shall be performed to the requirements of this ETS, however; CTOD

testing is not required. If a full test procedure cannot be performed because of lack

of material (e.g. small diameter pipes, etc.), only the hardness tests and the

technically possible amount of Charpy tests shall be performed with the below

priority:

1) The notch crossing the fusion line symmetrically

2) 1) + 2 mm

3) 1) + 5 mm

4) The notch on the weld centre line

If the production test is not fulfilling the requirements the cause of failing shall be

established immediately and brought to the attention of Energinet.dk

9. Non-destructive examination

This section specifies the requirements to NDE for the structural welds performed on

the fabrication site.

Inspection categories are in accordance with the requirements stipulated in DNV-OS-

C101.

Non-destructive examination shall be carried out according to DNV-OS-C401,

Following methods are applicable:

Visual examination (VT)

Magnetic particle examination (MT)

Liquid penetrant examination (PT)

Ultrasonic examination (UT)

Radiographic examination (RT)

Eddy current (ET)

9.1 Extent of examinations

The extent of NDE shall be based on type and level of design stresses and on the

importance of the connection in question.

The welds shall be assigned inspection categories equal to the highest structural

category of the two components.


NDE shall be carried out to an extent not less than required in DNV-OS-C401.

9.2 NDE Qualifications

9.2.1 Examination organisation

The organisation performing NDE shall be an independent inspection unit accredited

according to EN ISO 17025 or equivalent.

9.2.2 Examination personnel

All personnel shall be certified in accordance with EN 473 or equivalent and the unit

shall as a minimum include one certified level III inspector, who shall have the

overall technical responsibility for the NDE activities, i.e. approval of procedures,

equipment, technique etc.

The personnel performing NDE shall, as a minimum be certified as level II, or work

under direct supervision of a certified level II person.

9.2.3 Procedures

All NDE shall be performed in accordance with agreed written procedures, which

have been approved by the responsible level 3 inspector and in accordance with the

requirements of DNV-OS-C401 standard.

9.3 Execution of NDE

All plates, tubulars and profiles in the structural categories Special and Primary shall

be checked by NDE according to one or more of the methods specified in DNV-OS-

C401.

Radiographic examination may be replaced by ultrasonic examination and vice versa,

when methodologically justifiable and in agreement with the Energinet.dk.

9.4 NDE procedure and acceptance criteria.

The acceptance criteria level shall, for special structures comply with ISO 5817 level

B. Welds of category primary/secondary shall comply with ISO 5817 level C.

9.4.1 Visual (VT) procedure and acceptance criteria

100% VT shall be performed on all welds.

EN 970 or AWS D1.1 shall be used as examination technique for visually examination

of weld preparation and finished welds.

Acceptance criteria for visual and magnetic testing shall be according to ISO 5817

quality level B or C with the additional requirement that pinholes, slag stripes, pores

etc. shall not be accepted for welds, which shall be coated.


9.4.2 Magnetic particle (MT) procedure and acceptance criteria

Examination technique shall be in accordance with EN 1290 or ASTM E 709.

Examination shall be performed for indications in any directions. AC electromagnetic

yoke shall be used.

Detection media shall be of liquid type, fluorescent or black. If black suspended

power is used, the examination surface shall be covered by a thin layer of contrast

paint.

Acceptance level shall be as per EN ISO 23278 2x or ISO 5817 level B or C

9.4.3 Radiographic testing (RT) procedure and acceptance criteria

Examination technique shall be in accordance with EN 1435 class B.

Acceptance level: EN 12517 level 1.

9.4.4 Ultrasonic testing (UT) acceptance criteria

The examination shall be performed and evaluated as follows:

Examination level: EN 1714 level B, annex A.

Acceptance level: EN 1712 level 2.

9.4.5 Liquid Penetrant testing (LP) acceptance criteria

Examination technique shall be in accordance with EN 571-1.

Acceptance level: EN 1291 2X.

9.5 Execution of NDE, structural fabrication

9.5.1 General

All NDE shall be performed after final post weld heat treatment, if applicable.

NDE examination shall, at the earliest, be commenced 48 hours after welding

completion. Alternatively, the welding can be heated to 200 °C and held at that

temperature for two (2) hours. NDE can then be executed after cooling to the

temperature required for performance of the examination.

This procedure is subject to Energinet.dk approval.

For welds in secondary structure (handrails, kick plates ladders e.t.c) not welded to

special or primary structures, NDE can be performed after cooling to the temperature

required for performance of the examination required.

All Plates which are subjected to significant tensile stresses in the thickness direction

in way of cross joints, etc. shall be ultrasonically tested after welding into the

structure, to make sure that lamellar tearing has not taken place. If steel with


improved through thickness properties (steel type 2 and 4) has been adopted, this

test may be reduced to spot-check only.

Welds in hollow sections shall be 100% leak tested or 100% MPI tested.

9.5.2 Sequence of examination

Visual examination shall always be performed prior to other examinations. When

examinations for detection of internal as well as external defects are required for the

same weld the examination for external defects shall be performed prior to the

examination for internal defects.

9.5.3 Surface conditions

The surface and the adjacent area to be examined shall be clean and free of all dirt,

grease, paint, spatter, heavy oxidation etc. that may interfere with the examination.

To assure the examination and interpretation of results the weld surface shall be

prepared by grinding, if necessary.

NDE shall be performed prior to application of linings and coatings.

9.5.4 Random examination

Where random examination (spot check) is required a complete examination of the

specified percentage of the welds in the lot shall take place.

The selection of welds to be examined may be at the discretion of the inspector from

Energinet.dk. Where practical, the selection shall ensure that the work product of

each welder or welding operator performing the welding is included.

9.5.5 Extent of examination in case of unacceptable welds

All unacceptable indications shall be removed. Where weld repair is required, the

repair area shall be re-examined for external defects prior to welding including 100

mm on either side. Weld repairs (or replaced welds) shall be examined with the

same method as the original weld.

Where random examination reveals unacceptable indications the following actions

shall be taken:

a) Two additional welds by the same welder or welding operator shall be

examined with the same examination method.

b) If the results of the examination according to a) are acceptable the defective

weld shall be repaired and re-examined and all welds in the lot are

considered acceptable.

c) If the results of the examination according to a) are unacceptable two further

welds by the same welder or welding operator shall be examined for each

defective weld.


d) If the results of the examination according to c) are acceptable, the defective

welds shall be repaired and re-examined, and all welds in the lot are

considered acceptable.

e) If the results of the examination according to c) are unacceptable, all welds

welded by the same welder or welding operator shall be either:

- Examined 100%. Repaired and re-examined as applicable.

10. Coating

The minimum requirements are given in Energinet.dk technical standard “Protective

Coating of Steel – ETS-25”

11. As-built documentation

As-built documentation shall be compiled and submitted by the contractor to

Energinet.dk after execution of the work. The as-built documentation shall include,

but not be limited to the following:

Documentation index

Third part inspection release note (If applicable)

Manufactures declaration of conformity (certificate of conformity)

List of as-built drawings

As-built traceability drawings. The traceability shall cover all welding, materials

and NDE of the structure

Dimension reports, when applicable

NDE reports

NDE personnel certificates

List of approved WPS

List of approved welders

Weight reports, when applicable

Approved deviation reports and technical site queries

List of material certificates

Material certificates

Coating documentation

The as-built documentation shall further be compiled in accordance with EDS - 02.


11.1 Deliverables

Contractor shall deliver the following set of documentation to Energinet.dk:

Shop and design drawings in AutoCAD and PDF format, as per EDS-01.

The electronic documentation shall be prepared with bookmarks.


12. Appendix

Appendix 1A. Steel Types and Quality for Topside structures

Steel Type

Material Type Material Dim Standard Steel Quality Description

ST1 Plates

Plates

Sections

Welded hollow sections

Seamless hollow sections

T ≤ 50 mm

T > 50 mm

All

All

All

EN 10025

EN 10025

EN 10025

EN 10219

EN 10210

S355J2

S355NL

S355J2

S355J2H

S355J2H

Primary Steel

ST2 Plates

Plates

Sections



T ≤ 50 mm

T > 50 mm

All

All

All

EN 10025

EN 10025

EN 10025

EN 10219

EN 10210

S355J2

S355NL

S355J2

S355J2H

S355J2H

Primary Steel with

requirements for improved deformation properties perpendicular to the surface of the product , EN 10164 Quality Class Z35

ST3 Plates

Plates

Sections



T ≤ 50 mm

T > 50 mm

All

All

All

EN 10025

EN 10025

EN 10025

EN 10219

EN 10210

S420N

S420NL

S420N

S420N

S420N

Primary Steel

ST4 Plates

Plates

Sections



T ≤ 50 mm

T > 50 mm

All

All

All

EN 10025

EN 10025

EN 10025

EN 10219

EN 10210

S420N

S420NL

S420N

S420N

S420N

Primary Steel with

requirements for improved deformation properties perpendicular to the surface of the product , EN 10164 Quality Class Z35

ST3-S Plates All EN 10225

EN 10225

S420G1+Q

S420G1+M

Special Steel:

ST4-S Plates All EN 10225

EN 10225

S420G1+Q

S420G1+M

Special Steel with requirements for improved deformation properties perpendicular to the surface of the product , EN 10164 Quality Class Z35

ST5 Plates

Plates

Sections



Bulb flats

All EN 10025

EN 10025

EN 10025

EN 10219

EN 10210

EN 10067

S235

S235

S235

S235

S235

S235

Secondary Steel.


Appendix 1B Steel Types and Quality for Sub-structure (Jacket)

Steel

Type

Standard Steel Quality

1 EN 10225 Plates: S355G9+N/G9+M

Sections: S355G11+N/G11+M

Welded hollow sections: S355G13+N

Seamless hollow sections: S355G14+Q/G14+N

2 EN 10225 Steel with requirements for improved deformation properties

perpendicular to the surface of the product , EN 10164 Quality Class Z35

Plates: S355G9+N/G9+M+Option 13

Sections: S355G11+N/G11+M+Option 13

Welded hollow sections: S355G13+N+Option 13

Seamless hollow sections: S355G14+Q/G14+N+Option 13

3 EN 10225 Plates: S420G1+Q/G1+M

Sections: S420G3+M

Welded hollow sections: S420G5+Q

Seamless hollow sections: S420G6+Q

4 EN 10225 Steel with requirements for improved deformation properties

perpendicular to the surface of the product , EN 10164 Quality Class Z35

Plates: S420G1+Q/G1+M+Option 13

Sections: S420G3+M+Option 13

Welded hollow sections: S420G5+Q+Option 13

Seamless hollow sections: S420G6+Q+Option 13

5 EN 10025 S235-S275


Appendix 2

Drawing 10H 04 050 Stair - Standard drawing.


Appendix 3

Drawing 10H 04 051 - Standard drawing, removable/fixed handrail.


Appendix 4

Drawing 10H 05 052 -. Standard drawing, removable handrail, heavy duty


Appendix 5

Drawing 10H4 04 053 -. Typical details, grating