174701442 BSP 12 Standard 601 Rev 3 0 the Welding of Metals PDF

Brunei Shell Petroleum Company Sendirian Berhad

BSP-12-STANDARD-601

THE WELDING

OF

METALS

This is a supporting document of activity BSP-12 Design, Modification, Construction and Abandonment of Facilities

Rev.

Owner:

Adnan Kasem (SEN/6)

3.0

Author:

Bruce Cowe (SEN/641)

“Hardcopy documents are not controlled.

BSP-12.S.601 The Welding of Metals

Revision Record REV 1.0 1.1 2.0 3.0

REVISION DESCRIPTION First Issue. Revision Page Second Issue Revised clause 331.1 on page 22.

AUTHOR(S)

SEN/641 SEN/641

REVIEWER(S)

DATE 28-4-2000 Feb-04 Nov-2005 Feb-2009

SEN/6, SEN/64

This document is not considered HSE critical and this revision shall have a maximum validity of five years after the last revision date. Beyond this, it must be assessed for relevance and re-validated in accordance with:

Document Control Procedure (BSP-02-P-1).

Suggestions for further improvement in this document should be sent to the Document Owner. Distribution

The document owner is responsible for distribution control. The original electronic version is stored in Live Link and accessible via BSP On Line web site. Paper copies are not controlled documents. Notice and Warning

Copyright  2009, Brunei Shell Petroleum Company Sendirian Berhad This document is the property of Brunei Shell Petroleum Company Sendirian Berhad (BSP), Seria KB3534, Negara Brunei Darussalam. Circulation is restricted to BSP and its designated associates, contractors and consultants. It must not be copied or used for any other purpose other than which it is supplied, without the expressed written authority of BSP. Except where provided for purposes of contractual requirements, BSP disclaims any responsibility or liability for any use or misuse of the document by any person and makes no warranty as to the accuracy or suitability of the information to any third party. Any misuse of the document is redressable by BSP.

12-S-601.doc “Hardcopy documents are not controlled.

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TABLE OF CONTENTS 1.

Introduction

2.

Scope

3.

Exclusions

4.

Changes From Earlier Revision

5.

Definitions

6.

Abbreviations

7.

Technical Specification

General Requirements -

Section-1

Welding of Structural Steels

-

Section-2

Welding of Pressure Vessels

-

Section-3

Welding of Pressure Piping

-

Section-4

Welding of Pipelines

-

Section-5

Welding of Duplex Stainless Steel Piping

-

Section-6

Welding of Duplex Stainless steel Pressure Vessels


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1.

INTRODUCTION The existing Welding of Metals standard: BSP-12.S.601 Rev-1.1, has been reviewed in view of updating the standard. It was found that a major portion of the standard was irrelevant and referenced standards and that their clauses are not in line with the new revisions of the International codes and standards. Hence, it was decided to issue a new revision to the existing standard.

2.

SCOPE This welding standard has been prepared for use by BSP and their QCS Personnel, Contractors, Sub-contractors, Vendors, Inspectors and Fabricators of offshore/onshore structures, Pipelines, Vessels and Piping as a mandatory document. The standard covers the minimum requirements as regards to materials, consumables, processes, personnel qualifications, testing and inspection requirements to be employed for all new welding/repair and maintenance works of BSP facilities. The standard is applicable for welding at vendor workshop, fabrication yards, and new fabrication at sites and for maintenance repair work at sites.

3.

EXCLUSIONS This standard does not cover welding of the following: Sub sea structural welding (wet welding) Sub Sea Hyperbaric Welding Fabrication of Marine Vessels, ships and associated facilities. Hot tapping or Online in-process welding Welding of Non-Ferrous and CRA clad piping and Vessels For each of the above cases Contractors shall develop separate welding procedures/qualifications and Quality control requirements, the same shall be submitted for review and approval by Company Welding Engineer.

4.

CHANGES FROM EARLIER REVISION Major changes made in the current revision of the standard are as follows: -

All the referenced codes and standards, and the relevant clauses have been updated to current revisions. Reference to old NAM standards are removed, instead current revision of DEP’s have been included. For welding of Structural steels Inspection and PWHT requirements are clearly specified. For welding of Pressure vessels additional requirements as specified in DEP’s have been included to maintain consistency. Welding of pressure piping section has been modified with respect to ANSI B31.3. Welding requirements for pipeline are made in line with current DEP. Inspection requirements for piping and pipeline welds have been modified to make it simpler. Welding of Duplex Stainless steel piping has been totally modified. New section given requirements for fabrication of Pressure vessels using Duplex Stainless Steel Material.


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5.

DEFINITIONS General Definitions Company or BSP

The Company or BSP is Brunei Shell Petroleum Company Sendirian Berhad, KB 3534 Seria, Negara Brunei Darussalam

Contractor

The Contractor is the party in contract with BSP, which carries out all the stipulated contractual requirements like design, engineering, procurement, construction, commissioning or maintenance of facilities.

Manufacturer/ Supplier/ Vendor

The Manufacturer/Supplier/Vendor is the party which manufactures, supplies materials / equipment or provides services to the duties specified by the Company/ Contractor

Shall

The word shall indicates mandatory requirement

Should

The word should indicates a recommendation

Sub-Contractor

The Company approved person or organization having contract with the Contractor to perform full or part of the approved work.

Specific Definitions Approval/Approved

Company’s written approval to proceed with the plan, procedure, process, welding, fabrication method, technique etc., submitted by the Contractor for review, without releasing in any way the Contractor from his obligation

Batch

Equivalent term for lot of electrode

Design Code

The code or standard specified by the Company to which the equipment/pipelines or piping shall confirm

Hold Point

Specific milestone set by Company for witnessing and beyond which the Contractor cannot advance work without Company’s approval

Inspection Release Note

A document issued by the Company or its representative to authorize shipment after fulfilling required inspection/testing/QA/QC requirements are fulfilled

Procedure Qualification Record

A record of welding variables used to produce an acceptable test weldment and the results of tests conducted on the weldment to qualifiy a welding procedure specification

Qualified Welder

A welder who has demonstrated the ability to produce welds that meets the requirements of this standard


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6.

ABBREVIATIONS

ANSI API ASME ASNT ASTM AWS Ceq CSWIP DSS EV FCAW FL GMAW GTAW HV10 HAZ ISO MT NACE NDT PCM PQR PREN PT PWHT RT SAW SDSS SMAW UT UTS WPS WPQT WQR


American National Standards Institute American Petroleum Institute American Society of Mechanical Engineers American Society for Non-Destructive Testing American Society for Testing and Materials American Welding Society Carbon Equivalent Certification Scheme for Welding Inspection Personnel Duplex Stainless Steel Essential Variable Flux Cored Arc Welding Fusion Line Gas Metal Arc Welding Gas Tungsten Arc Welding Vicker Hardness Heat Affected Zone International Organisation for Standardisation Magnetic Particle Testing National Association of Corrosion Engineers Non-Destructive Testing Material Cracking Parameter Procedure Qualification Record Pitting Resistance Exponent Number Liquid Penetrant Testing Post Weld Heat Treatment Radiographic Testing Submerged Arc Welding Super Duplex Stainless Steel Shielded Metal Arc Welding Ultrasonic Testing Ultimate Tensile testing Welding Procedure Specification Welding Procedure Qualification Test Welder Qualification Record

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7.

TECHNICAL SPECIFICATION This document contains six sections each of these referring to an international accepted welding standard based on application requirements:

General Requirements -

Section-1

Welding of Structural Steels

-

Section-2

Welding of Pressure Vessels

-

Section-3

Welding of Pressure Piping

-

Section-4

Welding of Pipelines

-

Section-5

Welding of Duplex Stainless Steel Piping

-

Section-6

Welding of Duplex Stainless Steel Pressure Vessels


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GENERAL REQUIRMENTS

The general requirements given below are applicable for all the sections of this specification and to all design codes contained in this specification.

1.0

General

Prior to start of production welding the Contractor shall submit all the relevant WPS/PQR along with weld map document, showing his reference number of the welding procedure specifications selected for use on each weld for Company Welding Engineer Review and Approval. Welding shall not commence until Company Welding Engineer review and approves all WPS / PQRs to be used in the project. Company Welding Engineer or Company QCS representative present at the fabrication site or Inspector from a Company appointed Third Party Inspection Agency will monitor all pre-qualification tests at their discretion. Contractor shall notify Company, giving seven (7) days advance notice of all the tests. Contractor shall be responsible for all PQR tests and examination. Contractor shall also engage a Third Party Certification body such as BV, Lloyds, GL, ABS, DNV etc to witness all the qualification tests. The contractor shall not be allowed to use BSP or any other Contractor’s prequalified welding procedures. The Contractor shall maintain his own welding procedure register. Sub-contractors shall not be allowed to use the main contractors qualified procedures. They should have their own qualified procedures. All the Welders employed in the project shall be qualified before start of the production welding. A welder may have 2 attempts during welder qualification. Failure of the two tests, he shall be retrained for a minimum of 1 week before any retest. Contractors shall provide a Snr. Welding Inspector to oversee all Welding procedure Qualification tests and Welder Qualification Tests. For all sites where welding/construction is carried out, the Contractor shall provide a fulltime dedicated Senior Welding Inspector qualified in accordance with BSP 12.P.10. Gas cylinders containing purging or backing gas used in the fabrication shall be free from external corrosion to avoid any untoward incidents happening at site.


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2.0

Procedural Qualification testing Positions (PQR) The production welding positions qualified by a PQR shall be as follows:

PQR test position 1F 2F 3F 4F 1G 2G 3G 4G 5G 6G 6GR+T,K,or Y MOCK UP 1G ROTATED

3.0

Qualified Welding Position 1F ONLY 1F+2F 1F+2F+3F ALL F POSITIONS 1G ONLY 1G+2G 1G+2G+3G 1G+2G+3G+4G 1G+2G+3G+4G+5G ALL POSITIONS EXCEPT T,K,&Y CONNECTIONS ALL POSITIONS 1G ROTATED ONLY

-

Welding procedures having PWHT shall require separate qualifications.

-

The thickness <5mm ≥5mm Where

-

The diameter ranges qualified shall be as follows: D < 6inch 0.5D - 2D D > 6inch 0.5D - unlimited

ranges qualified shall be as follows: t - 1.5t 0.5t – 2t ‘t’ is the thickness of the test piece.

Additional Procedure Qualification Tests Impact testing All procedural weld qualification tests shall include impact testing. The testing shall be carried out at the minimum design temperature or 0ºC, which ever is lower. For weld thickness less than or equal to 20mm the test shall be conducted on one set of three specimens taken at: -

Weld centreline Weld fusion line Weld fusion line +2mm(HAZ)

For weld thickness more than 20mm two set of specimens one set taken at 1mm below the cap and another set taken 1mm above the root shall be tested.


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If specifically not mentioned, the acceptance limit for standard 10X10 specimen shall be 27J minimum and 32J average. For reduced size samples the values shall be proportionately calculated. Hardness Testing All procedural weld tests shall require a macro and hardness survey as per ASTM E92 using a Vickers hardness tester with a 10kg maximum load.

PQR test piece 1,2,3,&4F 1,2,3,4,5G plate 5,6G,6GR pipe 1G rotated pipe

Number of Macros per test piece 2 2 3 (12,3,6 o’ clock position) 3 (12,3,6 o’ clock position)

Number of Hardness surveys 1 per macro 1 per macro 1 per macro 1 per macro

For structural steel, the maximum hardness value shall be 350HV10. For higher strength structural steels i.e. quenched and tempered a maximum value shall be agreed between the Company and fabricator. For pipelines, process piping and pressure vessels in sweet service, the maximum hardness value shall be 325 HV10. For pipelines, process piping and pressure vessels in sour service; the maximum hardness value shall be 248 HV10. Macro sections shall be prepared so that the whole cross section of the weld, HAZ and adjacent parent material be finished and etched to reveal the weld structure including the individual passes and the full extent of HAZ. The macro examination shall be carried out at 5X magnification minimum. Fillet weld macros shall show full fusion to the root of the fillet. Harness survey shall include, the weld, HAZ and the parent metal. Non-Destructive Testing All procedure qualification tests and welder test pieces shall be radiographed. Radiography of the test samples shall be done after 48 hrs. 4.0

Welding Personnel additional requirements All welders shall have a unique identification number or symbol assigned to them. This number or symbol shall appear on every production weld made by them. All welders shall carry, at all times during working hours, an identification card on their person. This identification card shall contain the following personal information: i) Name; ii) Passport Photograph; iii) I.C.Number iv) Extent/Range of Qualification and v) A BSP Verification Stamp.


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5.0

Expiration and Renewal of Qualification A welder’s certificate is valid for 6 months. After this period the certificate can be re-validated if the contractor produces inspection and NDT reports from a production weld, to show compliance with the essential variables contained within the original certificate. This evidence must be authenticated by either a BSP welding Engineer/QCS Engineer or a Third Party Certification Body such as BV, Lloyds, GL, ABS, DNV etc. If no proof is available as outlined above, then the welder shall perform a new qualification test.

6.0

Welding Consumables Only Consumables approved by Company welding engineer shall be used. Welding consumable used in production welding shall be the same as those specified in PQR. Consumables considered equivalent shall not be used. The E60XX series electrodes and Exx10 cellulose electrodes shall not be used. Only low hydrogen consumables shall be used, with diffusible hydrogen content less than 10ml/100g of weld metal. During use all electrodes shall be kept in heated quivers and shall be used within four hours of issue. Those electrodes not used within four hours shall be returned to the baking oven. Electrodes shall be baked a maximum of two times. During production welding the maximum weave width shall be 2.5 X electrode dia.

7.0

NDT Personnel Qualification All NDT personnel employed shall be qualified and meet the requirements as specified in BSP–12-P-10.


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SECTION –1 WELDING OF STRUCTURAL STEEL 1.0

INTRODUCTION This Section is applicable for the Welding of offshore and onshore structures and structural skids. ANSI/AWS D1.1 is the governing document with addenda / interpretations as outlined below be followed. In case other codes are followed the same shall be submitted for Company Welding engineer review and approval.

2.0

ADDENDA

2.1

General All materials used for fabrication and welding of offshore structures and structural skid shall meet the requirements specified in DEP: 37.19.10.30. For onshore the materials used shall be as mentioned in the design drawing or approved materials as per the design code. Otherwise weldability test shall be carried out before using non-specified materials.

3.

Amendment / Supplement to ANSI / AWS D 1.1 Clause 4.1.1.3 CVN Test requirements Impact tests shall be included in the welding procedure qualification for thickness greater than 5mm. Test shall be carried out at 0ºC or at minimum design temperature, whichever is lower. If specifically not mentioned, the acceptance criteria shall be 27 Joules minimum and 32 Joules average. Clause 4.4 Type of Qualification tests Add the following at the end of the clause: CTOD testing For base materials where CTOD testing has been specified, the same shall be carried out as part of procedure qualification for the welds. The CTOD-test with the Bx2B, through-thickness notched type specimen according to BS 7448 should be used. Three (3) test specimens shall be obtained for each test position. The tests shall be carried out at 0 Deg C or at minimum design temperature or whichever is lower. The required CTOD value has to be decided in each case, based on a fracture mechanics evaluation for the particular structure. When the minimum single CTOD-value at the required temperature exceeds 0.25 mm (0.20 mm for welds with PWHT), the test series is normally acceptable without a detailed fracture mechanics evaluation.


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Clause 4.7 Essential variables In addition to Table- 4.5, 4.6, the following changes in essential variables calls for requalification: − Weld Configuration The addition or deletion of back gouging or grinding on a WPS from the original PQR shall constitute an essential variable and a procedural qualification test shall be performed. This also applies to single sided weld configurations versus double sided welding configurations and single sided with a back weld added. - Welding process The addition or deletion of a welding process utilized in a procedural test is not permitted in the welding procedure specification sheet.

Clause 5.8 Stress Relief Heat Treatment Add the following at the start of the section: Stress relief or PWHT of welded joints in plates, tubulars and structural assemblies is required when the joint reference thickness exceeds the following values: -

40mm for tubular intersection welds 50mm for all other welds.

The soaking time for PWHT shall be minimum 1 hour per inch of weld reference thickness. However, joints with a reference thickness greater than above but less than 100mm may be exempt from PWHT if satisfactory toughness in the as welded condition can be demonstrated by means of crack tip opening displacement (CTOD) testing on the weld and heat affected zone. The toughness shall be demonstrated for the maximum weld thickness used. The design consultant should determine the required toughness with the approval of Company. If any welding is carried out on PWHT completed joint, re-post weld heat treatment shall be carried out on the repaired weld joint. However, the same shall be included in the weldability test of the base material and in WPS to prove second PWHT will not cause drop in mechanical properties.

Clause 5.8.3 Steels not recommended for PWHT Add the following at the end of the clause: For steels manufactured by Thermo-Mechanically Controlled Process (TMCP) PWHT of weld joints shall be prohibited.


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Clause 5.26 Repairs Add the following: Only using pre-qualified repair-welding procedure and employing welders having qualified for repair welding shall carry out repair welding. Before repair welding, the defect shall be completely removed. The excavated area shall have smooth transitions to the metal surface and allow good access for both NDT after excavation and subsequent repair welding. After excavation, complete removal of the defect shall be confirmed by MT or PT. After repair welding the complete weld shall be subjected at least to the same NDT as specified for the original weld. PWHT shall be performed after repair if specified for the original weld. Repair welding shall be carried out twice only on the same area. Clause 6.14 .6 Personnel Qualification Add the following UT operators employed for examining critical joints like TKY joints, and weld joints subjected to fatigue stress shall satisfy API RP 2X requirements plus requirements specified in BSP-12-P-10.

Clause 6.15 Extent of testing Add the following at the end of the section: The extent of testing for weldments in structural steel welded in accordance with this specification are tabulated below: Material Thickness =< 35 mm > 35 mm Jackets / Decks Piles Main / Skid Beam Can Sections Nodes Horizontal Bracings Diagonal bracings Conductors Legs Lifting Lugs: Main connection Stiffening Plate Shims Ring Stiffeners Stabbing Points Beam Stiffening Plates Other fillet welds Tubular fabricated at site - Long seam welds


100 % RT 100 % RT 100 % RT 100 % RT 100 % RT 100 % RT 100 % RT 50% RT

100% UT 100% UT 100% UT 100% UT 100% UT 100% UT 100% UT 50% UT

100% UT 100% MPI 100% MPI 50% MPI 10% MPI 10% MPI 10% MPI 100% RT

100% UT 100% MPI 100% MPI 50% MPI 10% MPI 10% MPI 10% MPI 100% UT

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Miscellaneous Fender Clamps Helideck structure Main Remainder Bridges End Diagonals in vertical plane Top and Bottom Chord Butt welds Drip pan Secondary Steel Fillet Welds General plates, gratings, ladder and hand rails. Equipment Skids Main beams, girders, flanges and tubular braces – Full penetration welds Partial penetration and Fillet welds Lifting pad eyes on Jacket, deck, equipment skids or other equipment Jetties Piles – Stringing or Jointing of pipe pipes at yard

For all thicknesses 100% MPI 100% UT or RT 100% MPI 100% UT or RT 100% UT or RT 10% RT 10% MPI 10% MPI 10% MPI For all thicknesses 100% UT or RT

100% MPI 100% UT & 100% MPI 100% RT/UT until welder performance is stabilised. Then can be brought down to 20% RT/UT 20% RT/UT

Jointing of piles at site for pile makeup Notes: 1) RT means radiographic testing (X-ray or Gamma ray) 2) UT means ultrasonic testing 3) MPI means Magnetic particle testing 4) 10% inspection means 1 weld tested in 10 welded joints 5) 50% inspection means 5 welds tested in 10 welded joints. 6) All welds shall be visually inspected before any NDT is carried. 4.

PRODUCTION WELDING ( Additional Requirements) Tubular members containing longitudinal seams shall be joined such that the seams shall be offset a minimum of 90°. Locations where pad eyes are to be welded shall have a UT lamination check and 100% MPI, prior to welding in position. NDT shall not be conducted until a minimum of 48 hrs has elapsed following completion of the weld. All flame cut edges shall be ground smooth prior to line up and subsequent welding. Temporary attachments may be removed by thermal cutting or grinding. If thermal cutting is employed, the attachment shall be cut off at a minimum distance of 5mm from the surface of the material then ground flush. Removal by hammering shall not be allowed. The ground surface shall have 100% MPI carried out. Flux used in the SAW process shall be recycled more than twice.


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SECTION – 2 WELDING OF PRESSURE VESSELS 1.

INTRODUCTION This Section is applicable for the Welding of Pressure vessels, ASME Sec VIII Div 1&2 or BS PD 5500 which shall be the governing document with addenda / interpretations as outlined below be followed. This part of the specification gives minimum guidelines to be followed for welding of Pressure vessels fabricated from Carbon steels, Low Alloy Steels and High Alloyed Stainless steels. ( DSS welding is covered in separate sections).

2.

ADDENDA

a.

General During fabrication of new vessels, deposition of weld metal, or weld build up, to restore the wall thickness of the base metal for strength consideration or for meeting minimum design wall thickness requirement shall be prohibited. Clause UW-38 Repair of weld Defects The clause shall be modified as follows: All weld repairs shall be performed by employing qualified repair weld procedures and welders qualified for repair welding. Repair procedures shall include: Cap repair Mid thickness repair Through thickness repair All repair welds shall be re-examined 100% employing same NDE method used for original weld. A weld with unacceptable defects may only be repaired twice at the same location. If the repair is not acceptable the complete weld shall be removed by grinding and weld surface shall be freshly prepared for new welding. Clause UW-40 Procedures for PWHT Based on process requirement or on code requirement, whenever PWHT is to done on the fabricated vessel, it is recommended to do PWHT of the full vessel in an enclosed furnace.

b.

Additional requirements In addition, based on which design code is used, all the amendments /supplements given in DEP 31.22.10.32 or DEP 31.22.20.31-Gen, shall also be applicable.


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c.

The following additional requirements with respect to ASME Sec IX shall also be met as Sec VIII refers to it.

General: For welding of small bore pipe work (DN75 and smaller) the following shall apply: The welding process to be used shall be limited to GTAW welding. The GTAW welding machine shall have the capability of surge pulse start. Clause QW 170: Notch Toughness Test Delete the clause and replace with: All welding procedure shall include impact testing .The acceptance criteria for standard 10 by 10 specimen shall be as follows: Minimum Average energy = 32J Minimum individual energy = 27J Clause QW 301.2: Qualification Tests Add the following sentence: For pressure retaining welds, for all positions only welders qualified in 6G position will be acceptable. When SAW process is used for fabrication of pressure vessels, an operator qualified in 1G position is acceptable.

Clause QW 304: Welders qualification Replace the clause as follows: All welders and welding operators performance test coupons shall be, visually examined, radiographed and mechanically tested, which include bend test. The mechanical test pieces shall be as per ASME Sec IX. Qualification of welders only by radiographic testing shall not be permitted.

3.

PRODUCTION WELDING Locations where pad eyes are to be welded shall have a UT lamination check and 100% MPI, prior to welding in position. Flux used in the SAW process shall be recycled more than twice. Temporary attachments may be removed by thermal cutting or grinding. If thermal cutting is employed, the attachment shall be cut off at a minimum distance of 5mm from the surface of the material then ground flush. Removal by hammering shall not be allowed. The ground surface shall have 100% MPI carried out.


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SECTION – 3 WELDING OF PRESSURE PIPING 1.

INTRODUCTION This Section is applicable for the Welding of Process/Utility piping, ASME/ANSI B31.3 which shall be the governing document with addenda / interpretations as outlined below be followed. This part of the specification gives minimum guidelines to be followed for welding of Carbon steels, Low Alloy Steels and Austenitic Stainless steel pipe welding. Welding requirements for Duplex Stainless Steel piping is covered under section-5.

2.

ADDENDA General During new piping fabrication deposition of weld metal, or weld build up to restore the wall thickness of the base metal for strength consideration or for meeting minimum design wall thickness requirement shall be prohibited.

3.

Amendment / Supplement to ASME / ANSI B31.3 CHAPTER: V

FABRICATION ASSEMBLY AND ERECTION

The clause numbering follows that of ASME B31.3 (2002). Where clauses of ASME B31.3 are not amended, they shall apply in entirety. Para 327 General Add the following: All welds shall be made either by SMAW, GTAW or SAW process. Use of other process shall require Company approval. For all diameters having single sided butt welded joints in C-½Mo, Cr-Mo, Stainless steel and Nickel alloy welds shall have the root pass and hot pass made by GTAW process with an appropriate backing gas shielding protection. GTAW shall be used for complete welding of all pipes, fittings and branches if the pipe outside diameter is less than 75mm. Either internal or external pipe clamps shall be utilized. Internal pipe clamps shall be used for pipe sizes DN250 and larger, for pipes less than DN250 external clamps should be used. When using external clamps at least 50% of the root shall be completed, equidistant around the pipe circumference, prior to the removal of the clamp. When using internal pipe clamps, the root run shall be 100% completed prior to removal of the clamp.


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Clause 328.2.1 Qualification Requirements Delete the clause e, use of consumable inserts or backing rings are not permitted. Clause 328.2.2 Procedure Qualification by others. Delete existing clause and replace as follows: Procedures qualified for other companies shall not be accepted. Procedures qualified by another contractor or sub-contractor shall not be accepted. Clause 328.2.3 Performance Qualification by others: Delete existing clause and replace as follows: Performance qualifications made for other companies shall not be accepted. Performance qualifications made by another contractor or sub-contractor shall not be accepted. Performance qualification of welders by Radiographic testing only is not acceptable. All welders and welding operators performance test coupons shall be, visually examined, radiographed and mechanically tested, which include bend tests. The mechanical test pieces shall be as per ASME Sec IX. Only welders qualified in 6G position shall be employed for welding of process and utility piping. Clause 328.3.1 Filler metal Add the following: Only Company approved consumables shall be used. For selection of filler materials, guidelines given in API 582, Appendix-A can be followed with final approval from Company Welding Engineer. For welding of Austenitic stainless steel piping to grades SS 304 / 316 welding consumable equivalent to SS 316L shall be used. Clause 328.3.2 and 328.3.3 Backing material and Consumable inserts Delete both the clauses. Clause 328.4.1 Cleaning Add the following: For Stainless steel, nickel and non-ferrous welds, equipments used for grinding and cleaning shall be dedicated for those works only and shall be free of sulphur or chloride containing elements. Wire brushes used for cleaning shall be of stainless steel grade.


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Clause 32.4.2 End Preparation Delete existing clause (a,1) and replace as follows: Bevelling shall normally be prepared by machining or by grinding. Cutting of pipes may be done by mechanical means, either flame cutting or plasma cutting. The following shall apply for various materials: -

For carbon and low alloy steel, flame cutting followed by oxide removal from surface by grinding to bright metal to a distance of 5mm from cut location.

-

For Stainless steel and for other high alloyed materials, only plasma cutting shall be used. The surface shall be ground to bright metal after plasma cutting.

Clause 328.4.3 Alignment Add the following: When two piping components of same nominal outer diameter having different wall thickness are welded, the internal diameter of the thicker member shall be tapered to 1:4. Wherever, possible such rectification shall be carried out by machining in shop rather than by grinding in the field. Add new subsection (e) Weld separation The toes of adjacent circumferential welds shall be separated by a minimum distance equal to the nominal outside diameter of the pipe. Where the above requirement cannot be met, the minimum distance between the toes of adjacent circumferential welds shall not be less than five times the nominal weld thickness or 50mm which ever is greater. For circumferential welds on longitudinally welded pipes, the longitudinal welds shall be so positioned that; the weld is at the upper segment of 120º of the pipe, any two adjacent longitudinal welds shall be at least 45º apart or 200mm apart, whichever is less. When it is not possible to meet the above separation requirements between two longitudinal welded joints, the minimum separation shall be greater of five times the nominal wall thickness or 50mm whichever is greater and the joint shall be radiographed. The above requirements are also applicable whenever welded fittings are welded to the pipe. Clause 328.5 Welding Requirements Add the following under clause-c Where root tacks welding is specified in WPS, for pipe upto 4” OD, a minimum of three tacks shall be deposited at eq-distance spacing. For pipe exceeding 4” OD, a minimum of four tacks shall be deposited. All WPS permitted bridge tacks, welded to the pipes shall be removed by grinding only.


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Whenever argon is used as purging or backing gas during welding it shall be of highest quality with oxygen level less than 50ppm. Use of socket welds shall be prohibited. Clause 328.6 Weld Repairs. Delete the entire section and replace as follows: Welds containing defects outside the acceptance limits of the applicable code and this specification shall be repaired and only two repairs shall be permitted on same location. All the repairs shall be carried out by employing qualified repair welding procedure and welders qualified for repair welding. The repair WPS shall be supported by appropriate PQR. The repair PQR shall be qualified by carrying out mechanical and NDT tests same as specified for the original PQR. In addition to welding details the repair WPS shall include: Method of examination of defect area Method of defect removal Under no circumstances cracks shall be repaired. When cracks were observed, the defective weld shall be cut out entirely. For partial penetration repairs, the total length of exaction shall not exceed 30% of the weld length. For full penetration repairs, the total length of excavation shall not exceed 20% of the weld length. Preheating and PWHT employed for original welds shall be employed for repair welds also. After completion of repair welding, the full extent of the repair weld shall be examined by the NDT method prescribed for original weld to a length extending 50mm beyond on either side of the repair. Should further unacceptable defects be found on re-inspection then the weld shall be cut out entirely. Clause 330.1 Preheating - General Add the following For carbon-manganese steel pre-heating is generally not required, unless condensation of moisture on the weld area is possible. For all other materials pre-heat temperatures specified in the table 330.1.1 to be followed. Preheating shall be carried out only by electric resistance heaters or by oxypropane torches fitted with rosebud pattern nozzles. Welding or cutting torches shall not be used. Clause 330.2.4 Interrupted Welding Delete existing clause and replace as follows: Interruption of welding should be avoided. In case interruption is unavoidable, a minimum of three passes or one third of joint thickness, which ever is 12-S-601.doc “Hardcopy documents are not controlled.

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greater shall have been completed. The weld shall be wrapped under thermal insulation to allow slow cooling. Upon resumption of welding, any preheat as required by approved WPS shall be applied. This is applicable for all materials irrespective of thickness. Clause 330.2.5 Interpass Temperature (new) The welding Interpass temperature shall be maintained as follows: For carbon and low alloy steels : 250-275ºC For Austenitic Stainless steel : 125-150ºC For Nickel Alloys : 150-175ºC Clause 331 Heat Treatment Add the following: Whenever Post Weld Heat Treatment (PWHT) is required based on code requirements, service/process requirement, the contractor shall submit a PWHT procedure for Company Welding engineer review and approval; this should be included in the WPS submitted for approval. All equipment used during PWHT shall be calibrated and certified by a third party inspection agency. When PWHT is required, where possible it is recommended to pre-fabricate to avoid PWHT at site. Where PWHT is specified in the WPS, it is recommended to do PWHT immediately after completion of weld. If for any reasons PWHT was not able to carryout immediately, the weld shall not be allowed to cool faster, to avoid this it shall be covered with thermal blanket to cool the weld at slower rate (post weld soaking treatment) and temperature shall not be allowed to fall below pre-heat temperature for minimum 3 hrs. Clause 331.1 Heat Treatment Requirements Add the following: All carbon steel materials with a weld through thickness of >19.5mm shall require PWHT in accordance with code (ASME B31.3). Should exemption or relaxation be sought from this clause the fabricator / contractor shall apply the principles of an Engineering Critical Assessment, on a case-by-case basis and using fracture mechanics, to demonstrate that PWHT can be waived without determent to the weld properties or performance in service. Irrespective of code requirements specified in Table 331.1.1, the following process conditions shall require PWHT for all carbon and low alloy steel welds of all thicknesses: Caustic and Ammonia service (refer fig 10.1, DEP 31.38.01.11) HF service Rich amine service irrespective of service temperature Lean amine with operating temperatures above 60 Deg C. NACE/ISO 15156 specified severe Sour service conditions High pressure, lethal Hydrogen service Alkaline Sour waters containing Carbonates 12-S-601.doc “Hardcopy documents are not controlled.

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Clause 331. 1.4 Heating and Cooling Delete use of local flame heating mentioned in the section. For in-situ PWHT, electric resistance heating bands shall be utilised. Clause 331. 1.5 Temperature Verification Delete the entire clause and add the following: Each PWHT cycle shall be verified by heat-treatment chart, which shall be identified by weld number, and shall be signed by a BSP representative present at site or the third party inspector present at site. A heat treatment certificate shall be issued for each item or batch or items heat-treated in a single cycle. This certificate shall contain the following information: Identification of the component being PWHT Actual heating and soaking rates as recorded on the temperature chart. Actual soak and withdrawal temperatures as recorded on the temperature chart. Material dimensions and specification Applicable welding procedure specification number Project description/code. If PWHT is done locally at site the minimum heated bandwidth shall be as follows:

Thermocouples shall be used for control and monitoring of PWHT temperature. Thermocouples shall be attached to pipe by capacitor discharge method and covered with thermal insulation to control heat loss. Calibration of thermocouples shall be verified via calibration certificate. The temperature measured by each thermocouple shall be recorded graphically throughout the whole PWHT cycle by means of a multi channel chart recorder. This chart shall be submitted together with PWHT report for company review and approval. 12-S-601.doc “Hardcopy documents are not controlled.

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The location and number of thermocouples required shall be as follows: For DN50 and below minimum one thermocouple shall be attached at 6o’clock position. For DN50 to DN 250 minimum two thermocouples shall be attached at 12 and 6o’ clock position. For diameter above DN250 to DN400, minimum three thermocouples shall be placed on the outside diameter at 12,6, and 9 o’clock positions, and if possible one thermocouple at 3o’clock position shall be placed on the inside diameter. For diameter DN 400 and above four thermocouples shall be placed on the outside diameter at 12, 3, 6, 9 o’clock position and if possible one thermocouple at 2o’clock position shall be placed on the inside diameter. The temperature difference between any of the two thermocouples shall not be more than 50ºC. Clause 331.1.6 Hardness tests Add the following: In addition to hardness requirements specified in table 331.1.1, the following general hardness requirements for heat-affected-zone and weld metal shall apply: 248 HV10 maximum for ferritic metals in H2, HF, caustic and sour service conditions where PWHT is mandatory. 300 HV10 maximum for ferritic materials in process and utility service (steam, air, water, non sour service). 248 HV10 maximum for High alloy ferritic steels in the PWHT condition. 350 HV10 maximum for 9% Ni steels in the as-welded condition. 290 HV10 maximum for 9Cr-1Mo modified steel (P91, T91) in the PWHT condition. For welds to be PWHT hardness measurement shall be carried out after PWHT. -

Clause 331 Bending and Forming Add the following: The requirements specified in DEP 31.38.01.31 shall be followed. Chapter VI

INSPECTION, EXAMINATION AND TESTING

Clause 340.1 General. Add the following: Before start of welding and fabrication Contractor shall prepare a test package containing Inspection and Examination procedures to be employed in the project and shall be submitted to Company QCS Engineer thro the project group for review and approval. Inspection of welds shall be carried out after final heat treatment in accordance with the inspection classes shown in (Table-1). The methods to be 12-S-601.doc “Hardcopy documents are not controlled.

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employed for inspection, the acceptance criteria for welds, and the progressive examination shall be in accordance with ASME B31.3 and as modified in this specification. Company shall have the final disposition on any weld. Any weld not accepted by the Company representative shall be rectified in accordance with ANSI 31.3 and of this specification. Clause 341.4.1(a) Visual Examination Sub-clause 2&3 shall be modified as follows: All finished welds shall be visually examined and observation shall be recorded. For Stainless steel welds, the weld acceptance shall be as per B31.3 plus DEP 30.10.60.31. Welds showing oxidation shall be acid pickled and passivated. If severe oxidation is noticed the weld shall be cut out and rewelded. (b) Other Examination Shall be modified as follows: The extent of examination and type of NDT to be employed shall be as per Table-1. Fillet welds shall be examined by MT or PT at the same frequency as specified for butt welds per fluid service and class. Branch connection welds over 25mm shall be radiographic tested where possible, if not UT examination shall be employed. If both the NDT methods are not possible MT or PT can be employed. Clause 342 .1 Personnel Qualification and Certification The Contractor shall be responsible for the undertaking of all the inspection and NDT required by this standard. All the requirements for NDT personnel and certification shall be in accordance with BSP 12.P.10 procedure. Clause 345 Testing Add the following: After all the NDT tests have been carried out successfully and to the satisfaction of Company representative present at the site, hydro-testing shall be carried out in accordance with Company standard BSP-12-S-103. Clause 346 Records Add the following: Pre-Welding Documentation Quality plan, QA/QC procedures - Weld plan/map - Approved WPS/PQR, repair procedures - List of welders and identification cards copy 12-S-601.doc “Hardcopy documents are not controlled.

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-

List of NDE operators and their qualification certificates Copies of Company approved deviations List of material certificates List of consumable batch certificates List of test equipments and calibration certificates

Post-Production Documentation - Certificate of Compliance - List of as build drawings with weld map - Copies of Company approved deviations - NDE reports - Repairs carried out - Hydrostatic test reports - Any other documents as per contract requirements.


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Table-1

MATERIAL

Extent of Non-destructive Testing

SERVICE

ASME RATING CLASS

RT 8) /UT2)

MT

DP

PMI

1)

N/A

6)

1)

N/A

Hydrogen, Very Toxic and lethal substances(5). Category –M piping with severe Cyclic conditions.

A

Hydrocarbon Process lines,

All Ratings

100 %

3),

7)

Design Temp < 0 °C Carbon & Carbon Manganese Steels, including C-½ Mo Steels

Corrosive Acids, Caustic, Ammonia and HF Design temp > 0 °C, B

6) 150, 300, 600

Corrosive Acids, Caustic, Ammonia and HF.

10 % Random4)

Design temp > 0 °C C

6) 900 and above

Corrosive Acids

100 %

3),

7)

1)

N/A

All Services & Utilities

Low Chromium – Molybdenum Steels (Ferritic Alloys)

D

All Services & Utilities (other than A, B,C)

150, 300, 600

10% Random4)

1)

N/A

E

All Services

All Ratings

100 % 7)

100 %

N/A

F

Low Pressure Utility Service, (Except Hydrogen & Very Toxic Substances5))

150, 300

10 % Random4)

6)

Austenitic Stainless Steels G Nickel & Nickel Alloys, including 5% &9% Nickel Steels Dissimilar Metal Weldments NOTES:

6)

6)

Hydrocarbon process lines, Hydrogen, Very Toxic Substances5), Low Temperature & All Services other than F

All Ratings

All Services

All Ratings

N/A

1), 3)

100% 100 %

7)

N/A 1), 3) 100%

H

6)

100 %

6)

N/A 1), 3)

I

All Services

All Ratings

100 %

100 %

100 %

6)

1)

All welds with through weld thicknesses > 25 mm shall be crack detected.

2)

Ultrasonic examination may be applied if the configuration precludes radiography and the pipe diameter > DN 100 and the nominal wall thickness > 10 mm.

3)

In the case of fillet, or reinforcement attached welds; radiography can be replaced by magnetic particle inspection or dye Penetrant inspection.

4)

The indicated minimum percentage of welds to be radiographed over the completed circumference shall cover all welders at least once every week.

5)

Hydrogen service and Very Toxic substances are defined in DEP 01.00.01.30 Gen

6)

Positive Metal Identification (PMI) shall be carried out on ferritic and high alloy steel welds and component parts, including 0.5 Mo steels, if any material identification or traceability is in doubt using portable X-ray fluorescence analyser.

7) All nozzle/branch connections, including small nipples, shall be radiographed, where possible. 12-S-601.doc “Hardcopy documents are not controlled.

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8)

9)

Radiography requirements: -

When Radiography is specified X-Ray shall be used. Gamma radiography can be used only when weld thickness exceeds 12mm or where X-ray is not practicable, e.g. site tie in welds. The type of film used shall be as per BSP work instruction document No: BSP-12.W.12.

-

An Image Quality Indicator (IQI) with sensitivity better than 2 % shall be achieved by means of source side location of the IQI. Where access only allows the use of film side IQI, the technique shall be proved by means of a representative sample with IQI set source side and film side.

In addition random hardness measurements shall be carried out where hardness restrictions are imposed due to process requirements or when welds are PWHT.


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SECTION – 4 WELDING OF PIPELINES 1. Introduction This section of the specification is applicable for welding of Carbon steel pipelines and related facilities, API Standard 1104 and DEP 61.40.20.30Gen is the governing document with modifications as detailed below. The welding work shall satisfy pipeline design codes requirements if any, which are not covered in this standard. 2.

Addenda

a.

General

specific

The Principal or Company mentioned in the governing DEP document shall be read as BSP. Deposition of weld metal, or weld build up to restore the wall thickness of the base metal for strength consideration or for meeting minimum design wall thickness requirement shall be prohibited. Only procedures qualified for BSP shall be allowed to be used for the welding of pipelines. Procedures qualified for other Companies shall not be allowed to use. Contractors shall qualify procedures on contract material. Essential variables for WPS and Welder Qualifications shall be as per DEP 61.40.20.30. Prior to start of production welding all relevant welding specification and supporting procedures shall be submitted for Company welding engineer review and approval. Branches and fittings having diameter ≤ 2” shall be welded using GTAW process. 3. Amendment/Supplement to DEP 61.40.20.30-Gen 1.5.2. Filler materials Add the following : Only low hydrogen electrodes with diffusible hydrogen content less than 10ml/100g of weld metal shall be used. 1.5.2.2 Storage and handling of filler metals and fluxes Add the following:


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Prior to the commencement of qualification or production welding, whichever is sooner, the Contractor shall submit a consumable handling procedure to the Company for review and approval. Welding qualification or production welding shall not commence until the consumable handling procedure has been approved by Company Welding Engineer. Consumable control shall be such that any basic low-hydrogen electrodes shall be used within four hours of issue to a quiver. Those electrodes not used within four hours shall be returned to the baking oven. Electrodes shall be baked a maximum of two times. The Contractor shall have a system of identification for baked electrodes. 1.5.3.2 Storage and handling Add the following: All gas cylinders present at site shall be new in condition with no visible sign of corrosion. Gas cylinders showing external corrosion shall not be permitted at the site and shall be removed immediately to the satisfaction of Company representative present at the site. 2.1. Procedure Qualification First para shall be modified as follows: Before production welding is started, WPS proposed for qualification shall be submitted to the Company Welding Engineer a minimum of two weeks prior to the proposed date of welding qualification. The WPS proposed shall be endorsed and signed by the Contractor's authorized representative prior to submission. The Company Welding Engineer shall review and indicate approval of the WPS proposed by endorsing "APPROVED FOR QUALIFICATION", the contract number, the date, and signature. Only an endorsed WPS shall be used for welding qualification. Contractor shall then conduct PQR on the contract material. 2.2 Record Add the following: The PQR submitted for Company Welding Engineer approval shall include the following Documents: -

The WPS Approved for Qualification with all the details specified in clause 2.3. The actual welding details specified in clause 2.3 Material / Consumables Certificates. Portable Arc Monitor Printout of the welding parameters. Summary of welding parameters including Heat Input calculation Pre-heat / PWHT records (as applicable) Visual Inspection Report. NDT Reports. Lab Test Report.

Welding parameters shall be recorded by means of a calibrated portable arc monitoring system with printout facility. The printouts shall be included in the PQR.


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2.6.1.1 Non-destructive testing of test welds Add the following: NDT on all Qualification welds shall only be performed using the equipment and procedures approved by Company Welding Engineer, which shall be employed for production welding. NDT of a Qualification weld shall serve as a qualification test for the NDT procedures and shall be witnessed by the Company representative present at the site. 2.6.1.2 Destructive Testing of Welds Add the following: All destructive testing shall be performed at the Company approved testing laboratory, and shall be witnessed certified by Company approved third party inspection agencies. The Contractor shall be responsible for the engagement and hiring of the inspection agency. All test reports shall be endorsed and signed by the testing organization, the Contractor, and the inspection agency that witnessed the testing. The inspection agency shall also issue a certificate of conformance which states that the testing practices and procedures were in compliance with API STD 1104 and this specification. 2.6.8.5 If the hardness result exceeds the specified maximum then three further impressions shall be made in close proximity to that which failed such that they do not mutually interfere. If all of the further tests are below the specified maximum then the test shall be accepted. 3.6.1 General Replace as follows: Qualification of welders by radiography testing only shall not be accepted under any circumstances. Full mechanical testing shall be carried out. 4.17 De-Magnetizing Add the following Contractor shall have proper de-magnetizing equipment at site at all times for use when pipe ends show magnetism not suitable for welding. 5.2.2 Radiographic examination. Add the following: For thickness less than 6mm gamma radiography is prohibited. For higher thicknesses gamma radiography can be used where X-ray is not possible with the approval from Company Welding Engineer, provided the NDT contractor can demonstrate he can achieve the required Radiographic sensitivity of 2% or better and Density without compromising the quality by conducting qualification tests. Radiography on pipe lay barges shall be by x-ray crawler. 12-S-601.doc “Hardcopy documents are not controlled.

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5.2.3 Ultrasonic examination. First Para. of this clause in DEP shall be modified as follows: In addition to 100% Radiography, 100% Ultrasonic examination shall be made in cases where GMAW or FCAW process is used in full or in combination with other process. 5.5 Extent of Inspection and Testing Add the following: The Company shall have the final disposition on any weld. Welds not accepted by the Company shall be rectified in accordance with DEP requirements and this specification. Use of Automatic UT method shall not be permitted. The NDT and QC personnel employed for Inspection and Testing shall meet the qualification requirements as mentioned in BSP procedureBSP.P.10. For all pipe lay projects minimum one Senior Welding Inspector shall always be present at all times at site/pipe lay barge and also a welding inspector shall be present at each welding station. 6.1 General Add the following: The external weld reinforcement shall merge smoothly with the adjacent surfaces of the parent material. The thickness of the external weld reinforcement or internal weld protrusion shall not exceed the following: Wall thickness (mm)

External weld reinforcement or internal weld protrusion (mm)

6.4 and under

1.6

6.4 - 12.7

2.5

Over 12.7

3.0

7.1.1 Authorization of Repair Add the following: All the repairs shall be carried out by employing Company approved repair welding procedure and welders qualified for repair welding. The repair WPS shall be supported by appropriate PQR. The repair PQR shall be qualified on contract material by carrying out mechanical and NDT tests same as for the original PQR.


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The repair welding WPS may be identical to, but separate from, the original welding procedure with the addition of the following: -

Method of defect removal NDT requirements to determine complete removal of defect Three separate qualifications shall be made, for Cap, mid thickness and Root.

Only one repair is allowed per weld. A second repair shall only be allowed with permission from the Company welding Engineer, or Company site representative, and shall only if the repair PQR is conducted (including all mechanical tests) simulating the conditions of the 2nd repair. 7.1.2. Removal of defects and repair Add the following. Repair welding shall be carried out by low Hydrogen electrode with vertical up progression, the repair shall have 150ºC pre-heat. The total repair length shall not exceed 40% of the total weld length. For partial penetration repairs, the maximum length of a single repair portion shall be 30% of the total weld length. For full penetration repairs, the maximum length of a single repair portion shall be 20% of the total weld length. Groove taper shall be included in the measurements. If post weld heat treatment is specified, this shall be applied to the whole welded joint 9.2 Procedure Qualification Add the following For online barge welding, procedure approval test shall be made on the pipe lay barge or on a simulated environment (removal of line up clamp, time lapse between passes, pipe movement, cooling etc etc..). Each pass shall be deposited at the welding station intended to be normal location for it in production welding. 11. Documentation Add the following: 11.1 General The following documentation packages shall be submitted to Company upon completion of the work. 11.2 -

Pre-Welding Documentation Quality plan, QA/QC procedures Weld plan/map Approved WPS/PQR, Repair procedures List of welders and identification cards copy List of NDE operators and their qualification certificates


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-

11.3 -

Copies of Company approved deviations List of material certificates List of consumable batch certificates List of test equipments and calibration certificates

Post-Welding Documentation Certificate of Compliance List of as build drawings with weld map Copies of Company approved deviations NDE reports Repairs carried out Hydrostatic test reports Any other documents as per contract requirements


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SECTION –5 WELDING OF DUPLEX AND SUPER DUPLEX STAINLESS STEEL PIPING 1

SCOPE This part of the specification covers circumferential welding and inspection of Duplex Stainless steel pipes, fittings and associated facilities. The scope is intended to cover both 22Cr and 25Cr Duplex/Super Duplex Stainless steel grades operating under non-sour conditions both onshore and offshore.

2.

CODES The welding of DSS piping shall be in accordance with ASME B31.3 and ASME pressure Vessel code, section IX.

3.

MATERIALS This part of the specification is applicable for welding of Duplex and Super Duplex Stainless pipe, flanges and fittings meeting piping class per BSP standard, BSP-12-Standard-102; 134XB, 334XB, 634XB, 934XB, 1534XB & 2534XB.

4.

WELDING CONSUMABLES

4.1

General Consumables shall be purchased from Company approved suppliers only. Each lot of filler materials shall be tested for deposited weld metal chemical composition, mechanical properties and corrosion properties as specified under clause 9.2. Welding consumables for Super Duplex stainless steel shall have chromium content at least 25% and the nickel content shall be minimum 9% and the nitrogen content shall be at least 0.15-0.2%. The PREN (PRE = %Cr + 3.3.MO + 16%N) of the filler material shall be higher than minimum specified for the base material. For Welding of DSS material, welding consumable of SDSS shall be used. All welding consumables shall be a low hydrogen type i.e10ml/100 g of weld metal. Inspection documents for the welding consumable materials shall be in accordance with ISO 10474 3.1.B. All welding consumables shall be identifiable to batch certificate. Unidentifiable welding consumables shall not be used.

4.2

Storage and handling Consumables shall be supplied in fully sealed packages and stored in a dry storage room in accordance with the Manufacturer's instructions. Consumables shall remain in their original containers, which shall be marked with the Manufacturer's name, the consumable trade name and the batch number. Consumables in containers that are not identifiable and traceable shall be removed from the work site. Consumables that show signs of damage or deterioration, e.g. cracked or flaked coatings, shall be disposed of. The storage room shall have a maximum relative humidity of 50%.


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All covered electrodes shall be properly identifiable up to the time of usage, each electrode being distinguishable by a coding marked near the grip end. Electrodes without a code marking shall not be used. Where necessary, covered electrodes shall be baked and issued to the work place in accordance with the Manufacturer’s instructions. Wire spools shall be stored in cabinets with the Manufacturer's wrapping in place and shall remain clearly identifiable up to the point of usage. Unidentifiable wire shall not be used. To have good traceability of all consumables used in welding of DSS/SDSS piping, Contractor should maintain a separate consumable register and good QA/QC system to the satisfaction of the Company. 4.3

Shielding gases The shielding and purge gas shall be industrial quality complying with ISO 14175, AWS 5.3.2 for purity and dew point. Generally approved shielding gas is Argon or Argon + Helium mixture with addition of 2% Nitrogen. Hydrogen shall not be added. The oxygen content in the shielding gas shall be less than 50ppm. All bottles containing shielding gas shall be identifiable and shall be new in condition without sign of external corrosion or rust on the body of the cylinder.

5

QUALITY SYSTEM The Contractor should maintain and operate a quality system in accordance with ISO 9001 or with an alternative standard if agreed by the Company. Before start of welding Contractor shall submit QA Plan, QC procedures for Company approval.

6. 6.1

QUALIFICATION OF WELDING PROCEDURES Welding Procedure Specification (WPS) Before procedure qualification welding is started a detailed WPS shall be prepared by Contractor and shall be submitted to Company Welding Engineer for review and approval. Applicable WPS shall make reference to the relevant piping classes and shall indicate the diameter and the thickness range as appropriate. The welding procedure shall be issued on ASME Sec IX form QW482. The WPS submitted shall also indicate repair-welding procedures separately. Only WPS approved by Company Welding engineer shall be used for procedure test welding. Butt welding procedures, branch welding procedures, fillet welding procedures, and repair-welding procedures shall be qualified separately. Test welding shall be performed under simulated site conditions using pipe nipples with a length of 500 mm or one OD, whichever is the greater. For flange/fitting welds, suitably sized test rings may be used. The WPS shall show the following non-technical information: -

date; revision number; contract number; project title; Contractor's name; and reference to this Specification.


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6.2

Essential Variables During Qualification welding if the essential variables are exceeded, the welding procedure shall be set as a new WPS and shall be completely re-qualified. If the essential variables are exceeded during production welding, the deposited weld metal shall be removed and the joint re-prepared. Welding A change to another welding process or a change from Process manual to automatic Base material

A change in UNS number, a change in PREN exceeding 2.5, a change in manufacturer or welding same product forms sourced from different manufacturer or welding different product forms.

Position

Any change in the angle of the axis of the pipe greater than 25º from that used for qualification

Wall thickness

Any change in wall thickness beyond the qualified ranges given below shall be considered an essential variable.

Butt Welds Fillet Welds

Test weld thickness (mm)

Qualified range (mm)

t ≤ 5

t

t > 5 a

0.75t

to 1.25t

0.75t to 1.25t 0.75a to 1.25a

‘t = nominal wall thickness a = theoretical weld throat dimension Diameter

Joint Design

Filler metal

Change in pipe diameter or branch diameter outside the following ranges: D < 323mm : 0.5D to 2D D ≥ 323mm : 0.5D to maximum to be welded A major change in joint design ( U to V groove). Minor changes in angle of bevel or land of the welding groove are not an essential variable. a change in the diameter of electrode or filler wire; a change in filler metal classification; a change of filler metal trade name/manufacturer

Direction

A change in welding direction from vertical downhill to vertical uphill or vice versa.

Shielding gas and flow rate

A change of flow rate to one beyond the range of ±10% of that qualified. Any increase in the oxygen content of the effluent backing gas beyond that qualified. A change in one shielding gas composition qualified.

Number and Sequence of pass

Any change in sequence of filling or capping passes beyond that required to accommodate the qualified range of joint dimensions. Any decrease in the number of passes before cessation of backing gas.

Electrical characteristics

Any change outside the range ±15% of the single values for volts, amps and wire feed speed determined from the WPQR.


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However, the parameters shall be controlled so that the arc energy shown in the production WPS i.e. ±10%. Preheat and Interpass temperature

A increase of more than 50ºC in the specified minimum preheat temperatures or any increase in maximum inter pass temperature

Post-weld heat treatment

The inclusion or omission of PWHT, or any change in PWHT parameters

Removal of line-up clamp

Removal of the line-up clamp at a stage earlier than stated in the agreed WPS

Repair welds

Partial penetration repairs made closer to the inside surface compared to the qualification welding

7. WELDING METHOD The first and second pass of the single sided welds shall be made by using the GTAW process. During welding the backside of welds shall be protected by gas purging. For subsequent layers the SMAW/GTAW process may be used. The use of permanent backing strip or consumable insert shall not be permitted. GTAW shall be used for complete welding of all pipes, fittings and branches if the pipe outside diameter is less than 75mm. 8. WELDING OF PQR TEST JOINTS – BUTT WELDS Sufficient test welds shall be made to extract all the destructive test specimens required for qualification testing. Test welding shall be performed under simulated site conditions using pipe nipples of 500 mm minimum. For flange/ fitting welds suitably sized test rings may be used. As much as possible all PQR’s shall be conducted on the contract material. Prior to commencement of test welding, the Contractor shall have available at the test site the following Company approved documents: - Original copy of the WPS proposal, endorsed ‘Approved for Qualification” - Original material certificates, or verified copies traceable to the items to be welded. - Batch certificates of welding Consumable. - Approved Consumable handling procedure - Written procedure to remove oxygen before welding of DSS pipes Company Welding Engineer/QCS Engineer or Company approved representative shall witness test welding. The Contractor shall give minimum 7 days notice to Company Welding Engineer/QC Engineer or Company approved third party inspector to witness the test welding. The following information shall be recorded for each pass of the test weld and shall form part of PQR. - Pass number - Welding process - Consumable diameter - Consumable trade name, classification and batch number - Electrode polarity, arc voltage, current - Gas composition, flow rate - Wire feed rate and travel speed 12-S-601.doc “Hardcopy documents are not controlled.

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- Preheat/Inter pass temperature - Pass sequence The test weld information shall be recorded on welding parameter sheets, as per QW-483 in Appendix-A of ASME Sec IX. Pass sequence shall be shown in the sketch on the ASME form. The welding records of the test welding shall be signed, dated and endorsed by the Company Welding Engineer and contractors Welding Engineer/Inspector/CA present a the time of test welding. 9.0

TESTING OF WELDED JOINTS - BUTT WELDS

9.1

Preparation Prior to removal of test specimens, the test weld shall be subjected to the NDT defined below in the presence of Company approved third party certifying authority. The NDT shall consist of the following: visual examination liquid penetrant testing; X-ray radiographic testing; and - Ultrasonic testing (for welds made by GMAW, GTAW, and/or FCAW only). The acceptance criteria shall be as stated in chapter VI of ASME B31.3 and the corresponding sections of this specification. Any weld, which fails to meet the acceptance criteria, shall not be offered for destructive testing. Visual examination of all butt welds shall include the pipe bore surfaces. The degree of oxidation present on these surfaces following welding shall be within the visual acceptance criteria of DEP 30.10.60.31-Gen. All test welds shall be sectioned at the locations shown in Figure A.

9.2

Destructive Testing of test weld Testing for procedure qualification shall be performed in accordance with ASME Sec IX and the additional requirements in paragraphs 9.2.1 to 9.2.6. All the tests shall be witnessed and certified by Company approved inspection agency. All test reports shall be endorsed and signed by testing organisation, the contractor and the third party certifying authority who witnessed the testing. All test reports shall be included in the PQR submitted to Company for review and approval.

9.2.1 Tensile Strength Test Tensile strength test shall be carried out on weld specimens as per ASTM A370 on one set of three specimens extracted at locations shown in Figure-A. 9.2.2 Macro / Microscopic examination and Hardness tests Specimens shall be extracted from the test coupon and prepared for macro and Microscopic examination in accordance with ASTM E340. The sections of the weld taken for macro, microscopic examination and hardness testing may also be used for ferrite measurement as required. The prepared sections shall be examined at a magnification of 5X for macro examination and at x400 for micro examination and photo macrographs at the same magnification shall be included in the WPQR. The microstructure of the weld shall be free from carbides, nitrides and intermetallic phases, presence of the above undesirable phases shall call for rejection


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of the weld procedure qualification sample and fresh weld sample shall be prepared. Hardness testing shall be performed in accordance with ASTM E92 using a 10 Kg load. Hardness indent locations shall be as below and shall be visible in the photo macrographs. For plate thickness less than 10mm the mid-thickness transverse may be omitted. The maximum individual hardness value shall not exceed the following: Alloy Hardness 22Cr 325 HV10 25Cr 350 HV10 9.2.3 Ferrite measurement The ferrite content shall be determined in accordance with Appendix 1 of DEP 31.40.20.34-Gen. The ferrite content shall be measured on all specimens 1 mm from both the inside and outside surfaces and be reported for the parent material, HAZ and weld metal. The ferrite content shall be in the range 40 - 60% for the parent material and 35 - 65% in the weld/HAZ regions. 9.2.4 Charpy V-notch impact testing Each procedure qualification shall include impact test unless the nominal wall thickness is less than 6mm. Testing shall be carried out in accordance with ASTM A370 at the minimum design temperature of the line if not known test shall be carried out at -40ºC. Specimens shall, wherever possible, be 10 x 10 mm full size. If these dimensions are not possible, sub-size 10 x 7.5 mm shall be extracted. If the latter are not possible, the specimens shall be 10 x 5 mm. Charpy impact testing may be omitted if a specimen at least 5 mm thick cannot be extracted. One set of three specimens shall be taken from the locations shown in (Figure A) shall be notched at each of the following positions: root weld centre line; root fusion line (50% intersection of notch); and - root fusion line + 2 mm. If the wall thickness exceeds 20 mm, an additional set of three specimens shall be prepared from the same location for each of the following positions: cap weld centre line; cap fusion line (50% intersection of notch); and - cap fusion line + 2 mm. These requirements are summarized in (Figure B). The acceptance criteria are detailed in table below: Each set of three specimens shall meet the following requirements: Specimen Size Charpy Energy mm Joules Minimum Average Minimum Single 10 x 10 50 40 10 x 7.5 38 32 10 x 5 25 20


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9.2.5 Corrosion test As part of procedure qualification a pitting corrosion test shall be carried out in accordance with ASTM G48 Method A using Ferric Chloride solution. The test shall be carried out for 24 hrs immersion at 25±1ºC for Duplex steel and 40±1ºC for Super Duplex steel. The test specimen shall be machined perpendicular to the weld axis. The specimen dimensions shall be full wall thickness by 10mm along the weld and 50mm across the weld. The test shall expose the external and internal surface and a cross section surface including the weld zone in full wall thickness. No flattening of the coupon material shall be carried out. Before the start of the testing the specimen shall be degreased, dried weighed to three decimal places and the weight recorded. On completion of the test period the specimen shall be rinsed, cleaned dried and re-weighed using the procedures specified in ASTM G-48A. The test acceptance criteria shall be: - No evidence of pitting examined at a magnification of X20. - Weight loss shall not exceed 10g/m2 (~0.1mm/yr) All samples shall be photographed and made available with PQR submitted for Company approval. 9.2.6 Chemical Analysis Chemical analysis shall be conducted on the root run of the weld metal. The elements required for calculation of the PRE shall be determined. The PRE value shall exceed the minimum specified for the base material to be welded. 9.2.7 Retests 9.2.7.1General If the results of destructive testing are unsatisfactory owing to defective specimen preparation or a localized weld defect, the Contractor shall inform the Company and obtain agreement to proceed with retests. 9.2.7.2 Tensile tests If a maximum of one tensile specimen does not meet the acceptance criteria, two additional specimens shall be tested. Both of the additional specimens shall meet the acceptance criteria. 9.2.7.3 Charpy V-notch impact tests For Charpy tests, if the specified minimum average value has been achieved and more than one specimen is below the specified average value, or one specimen is below the specified minimum individual value, a retest of three further specimens shall be made. All three individual retest values shall equal or exceed the specified minimum average value. 9.2.7.4Hardness test For hardness test, if only one hardness result exceeds the specified maximum then a minimum of three further indentations shall be made in close proximity to that which failed such that they do not mutually interfere. If all the further tests are below the maximum specified hardness the retest shall be accepted.


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9.2.7.5Corrosion tests Retesting shall be permitted only if failure can be reasonably attributed to test conditions or sample preparation. When testing is agreed, two further specimens shall be prepared and tested. Both the retest specimens shall meet the acceptance criteria. 9.2.7.6New WPS requirement If the test joint fails to meet the minimum requirements of this specification, a new WPS shall be established and qualification welding and testing shall be repeated. 10.

APPROVAL OF WPS/PQR After successful completion of NDT and destructive testing, Contractor shall submit the original WPS/PQR to be used for production welding along with supporting test results for review and approval by the Company Welding Engineer. Production welding shall not commence until the WPS/PQR has been endorsed ‘Approved for Fabrication’ with the date and contract number and signed by the Company Welding Engineer. Only those WPS/PQR shown on the approved WPS register shall be used in production.

11.

QUALIFICATION OF FILLET WELD JOINTS Qualification of fillet weld joints shall be carried out on separate PQR same as butt weld joints, except the following NDT & destructive tests shall only be applicable. NDT Tests - Visual Examination - Liquid Penetrant Test Destructive Tests - Macroscopic examination - Hardness measurement - Ferrite Measurement

12.

QUALIFICATION OF REPAIR WELD PROCEDURE The repair welding procedure shall be qualified in accordance with sections 6 to 11. A separate WPS shall be produced for qualification by simulated repairs to an appropriate test weld except that repairs to fillet welds may be qualified by a suitable butt weld repair PQR. Each type of repair shall be separately qualified, including, partial penetration and cap repair. Through thickness repairs are not permitted. In addition to the items required for normal PQR, the WPS for repair shall show the following: the method of excavation the NDE techniques applied to ensure removal of defects. Following NDE testing of repair test weld, destructive testing shall be carried out in accordance with the methods and acceptance criteria of section 9 &11. 1 transverse tensile 1 macro/micro examination and hardness testing ferrite measurement for partial penetration repairs, which shall include measurements, made in the new HAZ formed in the original weld;


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-

Charpy impact testing samples notched in the new HAZ formed in the original weld. Corrosion testing for full penetration repairs to include the junction of new and original weld metal. The acceptance criteria shall be as for the original welding procedure qualification. 13.

QUALIFICATION OF WELDERS Welding and welding operators shall be qualified in accordance with ASME section IX and of this specification in presence of Company Welding Engineer/QC Engineer or Company recognised Inspection authority using previously qualified welding procedures. For qualification of welder’s tests as per requirements specified for PQR needs to be carried out. For butt welds, welders shall be qualified by visual examination, radiographic testing mechanical testing and macro examination. For branch welds and fillet welds, welders shall be qualified by visual examination, liquid penetrant testing, macro examination and hardness testing. All welders and welding operators are qualified for single position through single qualification test. For welder qualification of welding branch connections or welds of special configurations shall be qualified by separate qualifications. Only welders qualified for groove welds can be submitted to particular qualification for welded branch connections. The limits of welder qualification should be the essential variables of the WPS as required in 6.2. Any change which necessitates requalification of the WPS should require requalification of welders to the new, qualified WPS unless the Company agrees that the variable that has changed has no effect on a welder's performance. During qualification of the welder, if the test weld does not meet the specified acceptance criteria, the welder may carry out two repeat tests provided that the failure can be attributed to unavoidable conditions and not to lack of training. Both of the repeat welds shall meet the specified acceptance criteria. Failure of one or both repeat welds shall result in disqualification of the welder until such time as the Contractor can demonstrate to the Company Welding Engineer that satisfactory training has been received. After agreement by the Company welding engineer the welder may then be presented for further qualification testing. Once the welder passes the qualification test, the Contractor shall assign each welder a unique identification number, letter or symbol to ensure traceability to specific welds. If a welder ceases to work for the Contractor, the unique identification shall not be reassigned to another welder. A welder qualification shall be valid for a period of six months. If it can be shown by means of the results of non-destructive testing carried out in accordance with the requirements of this specification, that during this period he has successfully produced welds in accordance with the approved welding procedure, the period will be automatically extended by another six months. After this period the welder shall be freshly re-qualified. Contractors shall engage Third party Certification body such as BV, Lloyds, GL, ABS, and DNV etc to verify and endorse the renewals.


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14.0

PRODUCTION WELDING

14.1

General No production welding shall be carried out before the WPS/PQR and welder qualification has been completed and approved by Company Welding Engineer. In addition project specific QA/QC plans and procedures shall be prepared and submitted for Company QCS Engineer approval. Before start of welding all the materials, consumables, shielding gas shall be made traceable with identification numbers to their material certificates. The preparation and welding of pipe components shall be in accordance with the qualified and approved WPS/PQR. The approved WPS/PQR shall be available at the construction site. Welding shall not be done when unfavourable weather conditions prevail. In those cases windshields may be used where practicable. For identification welds shall be marked to maintain traceability of welders to specific welds or parts of welds. The contractor shall maintain records of weld number and the welder identification for each weld for inclusion in documentation package.

14.2

Preparation for Welding All material shall be visually inspected upon arrival on the construction site for damage, corrosion, proper protection and marking. Any defects deviations shall be reported to the Company representative present at the site for review. DSS materials shall not be stacked together with other items of carbon steel or other stainless steel alloys. Any contact between stainless and carbon steel components shall be avoided. DSS items shall be stacked properly and shielded against adverse weather conditions. Fusion faces and the surrounding surfaces within a minimum of 25 mm of the joint shall be free from scale, moisture, oil, paint or any other substance, which may have a deleterious effect on the weld quality or progress. Prior to welding, the end preparation shall be degreased with a non-chlorinated solvent such as acetone. Care shall be taken to avoid contamination of prepared bevel surface and surrounding area with low melting point metals such as copper, zinc or paint and markers containing Zinc or chloride. For Bevel preparation either machining or grinding shall be used, plasma cutting is acceptable followed by removal of HAZ by grinding. Grinding wheels used shall not have been used on other materials. Arcs shall be struck only on fusion faces or on striking plates provided as an aid to arc starting. Stray arc strikes shall be removed by grinding. The ground area shall be liquid-penetrant tested and thickness-checked. Where the thickness is below the specified minimum, this section of pipe shall be removed. The Contractor shall ensure a good earth connection and periodically examine the condition of the earth cables and attachments. Any arcing from a poor connection shall be treated as a stray arc strike. Connections shall be made to the work by stainless steel clamps. Earth cables shall not be welded to piping components. The open ends of the pipe shall be capped when interruptions to work expected to last two or more hours occur. All open ends of pipe strings shall be capped off and sealed when welding is completed.


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14.3

ALIGNMENT The piping components shall be firmly supported in both the vertical and horizontal plane and no welding shall be carried out until the alignment specified in the approved WPS has been achieved. Any misalignment shall be reduced to a minimum by rotation of the pipe to achieve the best fit. Hammering or heating of the pipe shall not be permitted. If the offset exceeds 1.6 mm, provided that it is caused by dimensional variations within the specified tolerances, or if alignment of two pipeline components of different nominal thickness and the same outside diameter is required, joint design shall be in accordance with ASME 31.3. Any taper shall not be steeper than 1 in 4. If a pipe with one longitudinal seam is used, this seam shall be within the top 120º of the circumference. The longitudinal seams of consecutive pipes shall be offset by at least 100 mm or 45º apart.

14.4

USE OF LINE-UP CLAMP FOR BUTT WELDS Internal line-up clamps shall be used wherever possible and their design shall be such as to allow the introduction and containment of purging gases. These clamps shall have stainless steel inserts or shall be clad with a suitable material to prevent contact between the DSS pipe and CS clamp. External line-up clamps may be used for line pipe 150 NPS and below, for tie-in welds, and for special welds, such as connections to valves, flanges and fittings. Pipe shall not be moved or lowered off until the second pass has been completed. Where an internal or external line-up clamp cannot be used, alignment may be achieved using tack welds. Tack welds shall be temporary bar tacks using suitable duplex stainless steel material. Welding parameters shall be in accordance with the appropriate fill pass. Tack welding shall be performed only by welders qualified to weld with the WPS. The tack welds shall be removed by grinding as welding progresses around the joint. Fully penetrating root tacks shall not be allowed.

14.5

Preheating and Inter-pass Temperature Preheating is usually not required, unless welding is required to be performed below 15ºC or condensation of moisture on the weld area is possible, then a minimum preheat of 50ºC shall be applied to a bandwidth of at least 75mm either side of the joint. It shall be applied using electrical resistance heaters, hot air blowers or oxy-propane rose bud torches. Welding or cutting torches shall not be used. During welding a maximum inter-pass temperature of 150ºC shall be maintained. Temperature measurement shall be by thermocouple, thermo melt crayon or contact pyrometers. Thermo-melt crayon shall not be applied within the bevel area.

14.6

Welding Welding shall be carried out by processes as approved in the WPS/PQR, using approved consumables, shielding and backing gases. Before start of welding pipes shall be flushed with backing gas. The oxygen content of the exit gas shall be monitored using suitable oxygen measuring equipment and welding shall not commence until a level of 50ppm (0.005%) is attained. During welding of the


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root run 50ppm oxygen level in backing gas shall be ensured. For subsequent runs an oxygen level may be increased to 500ppm and maintained. If the oxygen level reaches above 500ppm welding must be stopped. The level of less than 50 ppm must then be re-established before further welding takes place, and slowly increased to 500ppm max as welding progress. Each run of weld metal shall be cleaned before further run is deposited. During welding of DSS the heat input shall be maintained at 2.5Kj/mm max and for SDSS a lower heat input of 1.5Kj/mm max is preferred. All welds shall be continuous and multipass. They shall be properly sized to develop the full strength of the thinner of the two components joined. The weld reinforcement at the cap for thickness 6.4mm and below shall not exceed 1.6mm. For wall thickness greater than 6.4mm the weld reinforcement at the cap shall not exceed 3.2mm. The toes of adjacent circumferential welds shall be separated by a minimum distance equal to the nominal outside diameter of the pipe. Where the above requirement cannot be met, the minimum distance between adjacent welds, other than two circumferential welds, shall be not less than 5 times the nominal wall thickness or 50mm whichever is greater. Welds of branch connections and attachments should not overlap main seam welds nor interfere with welds of other attachments and shall be at least 45º apart. Longitudinal welds shall be positioned that the welds are in upper segment of the pipe, between ten and two o’ clock. Any two adjacent longitudinal welds are staggered to a minimum distance of 100mm. Interruption of welding should be avoided. If interruption is unavoidable, a minimum of three passes or one-third of the joint thickness, whichever is greater, shall have been deposited. On resumption of welding any preheat requirements specified in the approved WPS shall be applied. Welds shall be left as welded and shall not be treated with a flame torch or other mechanical means to change their appearance other than cleaning and dressing operations specified in the WPS. Welds shall not be peened. A circular tight cap, of a design which will not damage pipe ends shall be used to cover the open ends of the pipe and shall be placed on the line at the end of each day’s work to prevent entry of foreign material. Caps shall not be removed until commencement of the following day’s work. When fabrication is completed, all surfaces adjacent to the welds shall be cleaned of spatter, burrs and other imperfections which could interfere with radiographic or ultrasonic inspection. 15

INSPECTION AND TESTING OF PRODUCTION WELDS

15.1

General The Contractor shall be responsible for undertaking of all the inspection and NDT required by this inspection. The primary NDT method shall be X-ray radiography. Ultrasonic and liquid penetrant examination may supplement radiography and shall be used to interpret doubtful indications in the radiographs or for welds inaccessible for radiography. Welding and NDT inspection personnel shall be qualified in accordance with BSP.12.P.10 specification. Additionally the qualification requirements for radiographic interpretation shall be CSWIP and qualified for DSS/Austenitic stainless steels.


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15.2

Extent of Inspection and Testing Prior to welding, the Contractor shall examine free-issue materials for damage and compliance with the relevant materials specification. All damage and discrepancies shall be reported immediately to the Company representative present at the site. Before start of examination all NDE procedures shall be submitted to Company Welding Engineer/QC engineer for review and approval. All the NDT personnel qualifications and approvals shall be in line with BSP.12.P.10 procedure. Acceptance rejection of weld defects shall be as per B31.3.

15.3

Visual Examination All welds shall be 100% visually examined in accordance with ASME B31.3; where accessible the extent of oxidation on the root and HAZ surfaces of single sided welds shall be assessed for comparison with the visual acceptance criteria of DEP 30.10.60.31.Gen. If excess oxidation is noticed the pipe weld section shall be acid pickled and passivated in accordance with DEP 30.10.60.31.Gen both internally and externally. Detail for pickling and passivation to be agreed with the Company. Indications showing physical damages next to weld (e.g. Arc burns, damage of a sharp nature, weld beads etc) shall call for rejection of welds.

15.4

Radiographic Testing All butt welds including branch welds shall be radiographic tested in accordance with ASME B31.3; the extent of testing shall be 100% using X-rays. The film used for radiographic testing shall be of fine grain Class-II, for weld thickness more than 12mm and Class-1 film, shall be used for weld thickness less than 12mm. Image quality indicators used shall be of DIN wire type. The radiographic density of the exposed film shall be 2% minimum and 3.5% maximum. The radiographic sensitivity shall be 2% or better. Use of Gamma radiography is permitted only when wall thickness exceeds 25mm and Class-1 film shall be used. Cobalt-60 isotope shall not be used for gamma radiography. Additionally, NDT contractors shall prove by NDT procedure qualification using DSS material that they can produce a radiographic sensitivity of 2% or better. This shall be carried out afresh for each new project. The number of exposures for both X-ray and gamma radiography shall be as per Appendix-A.

15.5

Ultrasonic Testing If the physical configuration prevents radiographic testing, all those welds shall be tested by Ultrasonic testing in accordance with ASME B31.3. Calibration shall be done using specially prepared DSS calibration blocks. In addition 100% dye penetrant test shall also be carried out.


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15.6

Fillet Welds Fillet and branch welds where radiography/ultrasonic testing is not feasible shall be subjected to 100% visual and liquid Penetrant test in accordance with ASME B31.3.

15.7

Ferrite Measurement and Hardness Check Ferrite content and hardness check shall be conducted on 20% of production welds. On each test weld an average of three measurements shall be done on the weld metal and HAZ. For random check on welder’s quality assurance, contractors shall ensure that a minimum of 2% of the welds made by each welder is included in the overall percentage examined. The acceptance criteria shall be same as for the WPS/PQR. This results of the test shall be recorded in the fabrication dossier. In case if the ferrite content measured exceeds the acceptance limit, those welds shall be rejected. Further, ferrite measurement of all the untested welds carried out by the same welder shall be carried out.

16.0

REPAIR AND REMOVAL OF DEFECTS Welds containing defects shall be repaired only if approved by the Company. A weld with defects shall be repaired only once. Root repairs and cracks shall not be repaired, those welds shall be cut entirely. After further NDT, if the repair is unacceptable then the complete weld and HAZ should be removed. Full penetration repairs shall not be repeated. All weld repairs shall be carried out by using, qualified repair procedures employing welders qualified for repair welding. The removal of weld metal, or portions of the parent material, shall be by machining or grinding. Thermal gouging methods shall not be used. Repair excavations shall be smoothly contoured and tapered, having a minimum included groove angle of 50º. Visual and liquid-Penetrant testing of the repair weld grooves shall be carried out prior to re-welding to confirm complete removal of the defects. The total repair length shall not exceed 40% of the total weld length. The maximum length of a single repair portion shall be 30% of the total weld length. Groove taper shall be included in the measurements. All repairs, which require excavation and re-welding, shall be re-radiographed. The radiograph shall extend for a minimum distance of 50 mm beyond either end of the repaired area measured on the face of the weld. If any defects are identified and found unacceptable then the complete weld and HAZ shall be cut entirely and re-welded newly. Welds on fittings shall be cutout a maximum of twice, and then the entire fitting has to be replaced.

17.0

HYDROTESTING After all the NDT tests have been carried out successfully and to the satisfaction of Company representative present at the site, hydro-testing shall be carried out in accordance with Company standard BSP-12-S-103.


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18.0

DOCUMENTATION

18.1

General The following documentation packages shall be submitted to Company upon completion of the work.

18.2

18.3

Pre-Welding Documentation Quality plan, QA/QC procedures - Weld plan/map - Approved WPS/PQR, repair procedures - List of welders and identification cards copy - List of NDE operators and their qualification certificates - Copies of Company approved deviations - List of material certificates - List of consumable batch certificates - List of test equipments and calibration certificates Post-Production Documentation - Certificate of Compliance - List of as build drawings with weld map - NDE reports - Repairs carried out - Hydrostatic test reports - Any other documents as per contract requirements


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FIGURE A Location of sampling for macro section and impact test specimens procedure qualification of butt welds


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Figure B

Location of impact test specimens for procedure qualification of butt welds


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SECTION-6 SPECIAL REQUIREMENTS FOR PRESSURE VESSLES FABRICATED FROM DUPLEX AND SUPER DUPLEX STAINLESS STEEL 1.0

General This section specifies special requirements for pressure vessels and its internals fabricated from Duplex and Super Duplex stainless steel material. This is in addition to the requirements specified under section “Welding of Pressure Vessels”.

2.0

Codes The welding of pressure vessel fabricated from SDSS and DSS shall be in accordance with ASME pressure vessel code Sec VIII Div-1 or BS PD-5500 and ASME Pressure vessel code Sec IX as specified in the design data book or in the purchase requisition.

3.0

Welding Consumables Details of specific consumables to be used and suppliers shall be submitted to COMPANY Welding Engineer review and approval prior to qualification testing. All welding consumables shall be identifiable to batch certificate. Unidentifiable welding consumables shall not be used. Welding consumables for Super Duplex stainless steel shall have chromium content at least 25% and the nickel content shall be minimum 9% and the nitrogen content shall be at least 0.15-0.2%. The PREN (PRE = %Cr + 3.3.MO + 16%N) of the filler material shall be higher than minimum specified for the base material. For Welding of DSS material, welding consumable of SDSS shall be used. Each lot welding consumable shall be tested for deposited all weld metal chemical composition, mechanical properties and corrosion properties as mention in this part of the specification. Welding consumables shall be selected to deposit weld metal with a controlled ferrite content, the weld metal shall have a ferrite content of 35% min. to 65% max. Only low hydrogen consumables shall be used. When DSS is required to be welded to ferritic steel, the ferritic steel shall be buttered with a transition layer of type, AWS E 309Mo/E309MoL or use Inconel 625 welding consumable.

4.0

Shielding and Purging Gases The shielding and purge gas shall be industrial quality complying with ISO 14175, AWS 5.3.2 for purity and dew point. Generally approved shielding gas is Argon or Argon + Helium mixture with addition of 2% Nitrogen. Hydrogen shall not be added. The oxygen content in the shielding gas shall be less than 50ppm.

5.0

Welding Processes Welding of DSS and SDSS shall be carried out using, Shielded Metal Arc Welding (SMAW), Gas Tungsten Arc Welding (GTAW), Submerged Arc Welding (SAW). Other methods may be used when approved by the COMPANY.


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The GTAW shall be used for the root pass on all single sided welds with purge gas. The purge gas shall be maintained so that the subsequent weld passes do not result in oxidation. Attachment welds like branches and fitting having diameters ≤ 2” shall be welded fully with GTAW process. 6.0

Qualification of Welding Procedures

6.1

Welding Procedure Specification All welding shall be performed in accordance with approved welding procedure specifications (WPS). The welding procedure shall be issued on ASME Sec IX form QW-482. The WPS submitted shall also indicate repair-welding procedures separately. Separate procedures shall be developed for butt welds, branch welds and fillet welds.

6.2

Essential Variables Essential variables and supplementary variables shall be in accordance with ASME Sec-IX or equivalent and modifications as specified below. During Qualification welding if the essential variables are exceeded, the welding procedure shall be set as a new WPS and shall be completely re-qualified. If the essential variables are exceeded during production welding, the deposited weld metal shall be removed and the joint be re-prepared. Welding Process

A change to another welding process or a change from manual to automatic

Base material

A change in UNS number, a change in PREN exceeding – 2.5, a change in manufacturer or welding same product forms sourced from different manufacturer or welding different product forms.

Position

Any change in the angle of the axis greater than 25º from that used for qualification.

Wall thickness

Shall be in line with ASME Sec IX requirements

Diameter

Shall be in line with ASME Sec IX requirements

Joint Design

A major change in joint design (U to V groove). Minor changes in angle of bevel or land of the welding groove are not an essential variable.

Filler metal

a change in the diameter of electrode or filler wire; a change in filler metal classification; a change of filler metal trade name.

Direction

A change in welding direction from vertical downhill to vertical uphill or vice versa.

Shielding gas and flow rate

A change of flow rate to one beyond the range of ±10% of that qualified. Any increase in the oxygen content of the effluent backing gas beyond that qualified. A change in one shielding gas composition qualified.

Number and Sequence of pass

Any change in sequence of filling or capping passes beyond that required to accommodate the qualified range of joint dimensions. Any decrease in the number of passes before


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cessation of backing gas.

6.3

Electrical characteristics

Any change outside the range ±15% of the single values for volts, amps and wire feed speed determined from the WPQR. However, the parameters shall be controlled so that the arc energy shown in the production WPS i.e. ±10%.

Preheat and Interpass temperature

A increase of more than 50ºC in the specified minimum preheat temperatures or any increase in maximum inter pass temperature

Post-weld heat treatment

The inclusion or omission of PWHT, or any change in PWHT parameters

Repair welds

Partial penetration repairs made closer to the inside surface compared to the qualification welding

Procedure Qualification Record All welding procedures shall be qualified in accordance with ASME Sec IX, QW 482 or equivalent. Previously qualified procedures can be employed with the approval of the Company Welding Engineer provided the Essential variables mention in A6.2 are met and all the PQR tests mentioned in A6.4 are met. Welding procedures qualified with Duplex Stainless steel base metal does not qualify welding Super Duplex Stainless steel and vice-versa. For fresh qualifications, test coupon welding shall be witnessed by Company Welding Engineer/QCS engineer or Qualified Inspector from Company approved third party agency.

6.4

Testing of PQR Test Coupons – Butt Welds

6.4.1

Preparation Prior to removal of test specimens, the test weld shall be subjected to the NDT defined below in the presence of Company approved third party inspector. The NDT shall consist of the following: Visual examination Liquid penetrant testing; X-ray radiographic testing; and Ultrasonic testing (for welds made by GMAW, GTAW and /or FCAW only)) The acceptance criteria shall be in accordance with ASME Sec VIII Div-1 or equivalent. Any weld, which fails to meet the acceptance criteria, shall not be offered for destructive testing. If pipes are used as test sample, Visual examination of all butt welds shall include the pipe bore surfaces. The degree of oxidation present on these surfaces following welding shall be within the visual acceptance criteria of DEP 30.10.60.31-Gen. All test welds shall be sectioned from the test coupon at the locations shown in Figure QW-463, ASME Sec IX.

6.4.2

Destructive Testing of Weld Destructive Testing for procedure qualification shall be performed in accordance with ASME Sec IX and the additional requirements in paragraphs A6.4.3 to A6.4.7 All the tests shall be witnessed and certified by Company approved inspection agency. All test reports shall be endorsed and signed by testing


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organization, the contractor and the third party inspector who witnessed the testing. All test reports shall be included in the PQR submitted to Company for review and approval. 6.4.3

Macro, Micro examination and hardness tests Specimens shall be extracted from the test coupon and prepared for macro and Microscopic examination in accordance with ASTM E340. The sections of the weld taken for macro, microscopic examination and hardness testing may also be used for ferrite measurement as required. The prepared sections shall be examined at a magnification of 5X for macro examination and at x400 for micro examination and photo macrographs at the same magnification shall be included in the WPQR. The microstructure of the weld shall be free from carbides, nitrides and inter-metallic phases, presence of the above undesirable phases shall call for rejection of the weld procedure qualification sample and fresh weld sample shall be prepared. Hardness testing shall be performed in accordance with ASTM E92 using a 10 Kg load. Hardness indent locations shall be as below and shall be visible in the photo macrographs. For plate thickness less than 10mm the mid-thickness transverse may be omitted. The maximum individual hardness value shall not exceed the following: Alloy 22Cr 25Cr

Hardness 325 HV10 350 HV10

1 .5 ± 0 .5 m m x x

x

x x

x

x x

x

x xxx

x x x

x x

x

0 .5 t

x x 1 .5 ± 0 .5 m m

F ig u r e -1 H a r d n e s s I n d e n t L o c a tio n

6.4.4 Ferrite measurement The ferrite content shall be determined in accordance with Appendix 1 of DEP 31.40.20.34-Gen. The ferrite content shall be measured on the specimens 1 mm from both the inside and outside surfaces and be reported for the parent material, HAZ and weld metal. The ferrite content shall be in the range 40 - 60% for the parent material and 35 - 65% in the weld/HAZ regions. 6.4.5 Impact Testing Each procedure qualification shall include impact test unless the plate thickness is less than 6mm. Testing shall be carried out in accordance with ASTM A370 at the minimum design temperature of the pressure vessel if not known test shall be carried out at -40ºC. Specimens shall, wherever possible, be 10 x 10 mm full 12-S-601.doc “Hardcopy documents are not controlled.

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size. If these dimensions are not possible, sub-size 10 x 7.5 mm shall be extracted. If the latter are not possible, the specimens shall be 10 x 5 mm. Charpy impact testing may be omitted if a specimen at least 5 mm thick cannot be extracted. One set of three specimens shall be taken from the test coupon at location as shown in ASME Sec IX, fig- QW-463 and shall be notched at each of the following positions: -

root weld centre line; root fusion line (50% intersection of notch); and root fusion line + 2 mm.

If the wall thickness exceeds 20 mm, an additional set of three specimens shall be prepared from the same location for each of the following positions: -

cap weld centre line; cap fusion line (50% intersection of notch); and cap fusion line + 2 mm.

The requirements are summarised on figure shown below:


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The acceptance criteria are detailed in table below: Each set of three specimens shall meet the following requirements: Specimen Size mm 10 x 10 10 x 7.5 10 x 5

Charpy Energy Joules Minimum Average Minimum Single 50 40 38 32 25 20

6.4.6 Corrosion test As part of procedure qualification a pitting corrosion test shall be carried out in accordance with ASTM G48 Method A using Ferric Chloride solution. The test shall be carried out for 24 hrs immersion at 25±1ºC for Duplex steel and 40±1ºC for Super Duplex steel. The test specimen shall be machined perpendicular to the weld axis. The specimen dimensions shall be full wall thickness by 10mm along the weld and 50mm across the weld. The test shall expose the external and internal surface and a cross section surface including the weld zone in full wall thickness. No flattening of the coupon material shall be carried out. Before the start of the testing the specimen shall be degreased, dried, weighed to three decimal places and the weight recorded. On completion of the test period the specimen shall be rinsed, cleaned dried and re-weighed using the procedures specified in ASTM G48A. The test acceptance criteria shall be: - No evidence of pitting examined at a magnification of X20. - Weight loss shall not exceed 10g/m2 (~0.1mm/yr) All samples shall be photographed and made available with PQR submitted for Company approval. 6.4.7 Chemical Analysis Chemical analysis shall be conducted on the root run of the weld metal. The elements required for calculation of the PRE shall be determined. The PRE value shall exceed the minimum specified for the base material to be welded. 7.0

QUALIFICATION OF FILLET WELD JOINTS Qualification of fillet weld joints shall be carried out same as butt weld joints, except the following NDT & destructive tests shall only be applicable. NDT Tests - Visual Examination - Liquid Penetrant Test Destructive Tests - Macro and microscopic examination - Hardness measurement - Ferrite Measurement

8.0

QUALIFICATION OF REPAIR WELD PROCEDURE The repair welding procedure shall be qualified in accordance with section A6 & A7. A separate WPS shall be produced for qualification by simulated repairs to an appropriate test weld except that repairs to fillet welds may be qualified by a suitable butt weld repair PQR.


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Each type of repair shall be separately qualified, including full penetration, partial repair and cap repair. In addition to the items required for normal PQR, the WPS for repair shall show the following: the method of excavation the NDE techniques applied to ensure removal of defects. Following NDE testing of repair test weld, destructive testing shall be carried out in accordance with the methods and acceptance criteria of section 6 & 7. 1 transverse tensile 1 macro examination and hardness testing Ferrite measurement for partial penetration repairs, which shall include measurements, made in the new HAZ formed in the original weld, Charpy impact testing samples notched in the new HAZ formed in the original weld. Corrosion testing for full penetration repairs to include the junction of new and original weld metal. The acceptance criteria shall be as for the original welding procedure qualification. 9.0

QUALIFICATION OF WELDERS Welding and welding operators shall be qualified in accordance with ASME section IX and of this specification in presence of Company Welding Engineer/QC engineer or Company recognized Inspection authority using previously qualified welding procedures. For qualification of welder’s tests as per requirements specified for PQR needs to be carried out. For butt welds, welders shall be qualified by visual examination, radiographic testing, mechanical tests, macro/micro examination and hardness testing. For branch welds and fillet welds, welders shall be qualified by visual examination, liquid penetrant testing, mechanical testing, macro/micro examination and hardness testing. The limits of welder qualification should be the essential variables of the WPS. Any change which necessitates requalification of the WPS should require requalification of welders to the new, qualified WPS unless the Company agrees that the variable that has changed has no effect on a welder's performance.

10.0

Production Welding

10.1

General The pressure vessel vendor shall not start his production welding before Company Welding engineer reviews and approve the proposed WPS/PQR. In addition project specific QA/QC plans procedures and ITP shall be prepared and submitted for Company review and approval. Along with actual production welding, fabricator shall prepare a production test coupon, which comprises of one long seam, one circ seam and one nozzle welding. The material for production coupon shall be the actual used for fabrication of the vessel. These production coupons shall be tested for all the weld qualification tests specified above. If any hot forming or cold forming is involved with PWHT / solution annealing, the same shall be included in the production coupon production sequence.


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10.2

Preparation and Fit-up Preparation of weld bevels shall preferably be carried out by mechanical methods. Plasma arc cutting may be used when followed by grinding. All edges on Duplex stainless steel formed by power cutting shall be ground off at least 1 mm. Cutting, grinding and welding of Duplex stainless steel material shall be carried out in exclusive bay/shop. Grinding discs and wire brushes shall be reserved for use on Duplex stainless steel only. Only double sided welding is preferred, unless internal access does not permit welding from both sides. Care shall be taken to ensure that the weld preparations are correctly profiled and to clean metal prior to welding. Visual examination shall confirm that the preparation is smooth and uniform, free from tears, cracks, gouges and other discontinuities, which might affect the weld quality. The weld bevel and the adjacent areas shall be free of moisture and oxides. The fit-up tolerances shall be specified in the welding procedure specifications (WPS).

10.3

Forming Dished heads and shells shall be either cold formed and solution heat-treated or hot formed and solution heat-treated. Solution heat treatment shall consist of heating the head rapidly to a temperature in excess of 1020°C, a hold period followed by rapid cooling in air or water. Solution heat treatment may be deleted if either: 1)

Cold deformation does not exceed 5%. Consideration shall be given to localized cold deformation in the knuckle region in assessing the need for solution heat treatment.

2)

Hot forming is completed at a temperature above 1020°C followed by rapid cooling in air or water.

In the cold forming of heads by spinning; consideration shall be given to the need for intermediate and final solution heat treatment. The allowable level of cold deformation prior to intermediate heat treatment shall be agreed with the Purchaser. Full details of intermediate and final solution heat treatment procedures shall be submitted to and approved by the Company Welding Engineer. In order to remove oxide scale produced in heat treatment the complete dished heads shall be subject to a pickling and passivating treatment. Detail for pickling and passivation to be agreed with the Company. The inside and outside surfaces of the knuckle area shall be inspected 100% with liquid penetrant examination. In order to confirm the properties of Duplex stainless steel heads, test samples shall be subject to similar cold work levels and heat treatments. These samples shall be subject to the following tests: a) Tensile b) Impact c) Macro for hardness and micro examination.


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In forming the cylindrical shell the rolls shall be covered with a suitable buffer material such as to avoid contamination of the Duplex stainless steel. The forming tool shall be clean and free of surface imperfections or swarf. Carbon or sulfur containing lubricants shall not be used. Straightening with gas flames is not permitted. 10.4

Tack Welds Tack weld shall be carried out by qualified welders. Tack welds for single sided welding shall be completely removed. Tack welds for double sided welding may be incorporated into the main weld provided their ends are ground and feathered. They shall be of same size as root pass.

10.5

Preheat and Interpass Temperatures Preheating is not required. The bevel shall only be dried free of moisture. The inter pass temperature shall not exceed 150°C. Temperature measurement shall be by thermocouple or thermo melt crayons (Tempil sticks).

10.6

Welding Only qualified welders shall be used, and the welding shall be according to an approved WPS/PQR, approved consumables, shielding and backing gas damming procedure. The heat input shall not exceed the specified values in the WPS/WPQ and shall not exceed 2.5 KJ/mm max for DSS and 1.5KJ/mm max for SDSS. The inter pass cleaning of the DSS weld deposits shall be carried out with stainless steel wire brushes only. Weaving shall be 2.5 times the electrode dia. Temporary attachments shall be of same material type as that to which they will be attached. The attachments shall be completely removed and ground flush. The rectified area shall be subjected to dye penetrant inspection. All fillet welds shall be continuous. Post weld heat treatment (PWHT) shall normally not be carried out. When required the PWHT shall be in accordance with the code and the steel manufacturers recommendations. After heat treatment the internal surfaces shall be cleaned free of scale and oxides. On the completion of the welding the adjacent surfaces shall be cleaned free of all spatter, slag, flux and other carbonized material. If any oxidation is noticed the vessel shall be acid pickled and passivated in accordance with DEP 30.10.60.31.Gen both internally and externally. Detail for pickling and passivation to be agreed with the Company.


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11.0

Inspection and Testing The methods and extent of testing shall be in accordance with the data sheets and AFC drawings. All welds shall be 100% visually examined in accordance with the respective design code. All the welds shall be visually examined for extent of oxidation with the visual acceptance criteria of DEP 30.10.60.31.Gen. Radiography shall be used on all full penetration butt welds, branch welds and category-1 welds. . The film used for radiographic testing shall be of fine grain Class-II, for weld thickness more than 12mm and Class-1 film, shall be used for weld thickness less than 12mm. Image quality indicators used shall be of DIN wire type. The radiographic density of the exposed film shall be 2% minimum and 3.5% maximum. The radiographic sensitivity shall be 2% or better. Where radiography is not possible due to weld location Ultrasonic testing (UT) shall be carried out. For Branch and fillet welds where radiography or Ultrasonic testing is not feasible, dye penetrant examination shall be required. Gamma radiography is permitted only when weld thickness exceeds 25mm and class-1 film shall be used. Cobalt-60 isotope shall not be used for gamma radiography. Additionally, contractor shall prove by NDT procedure qualification using DSS material that they can produce a radiographic sensitivity of 2% or better. This shall be carried out afresh for each new project. The number of exposures for both X-ray and gamma radiography shall be as per Appendix-A. The acceptance criteria stated in ASME VIII div. 1, shall apply. Any defects found unacceptable shall be repaired using qualified weld repair procedure.

12.0

Hydrotesting After all the NDT tests have been carried out successfully the hydrotest can be carried out. For hydro testing the water used shall be of potable water grade with chloride content less than 250ppm. Seawater shall not be used. After successful completion of hydrotest the test water shall be drained off immediately and shall be dried off by using hot air to the satisfaction of vessel certifying inspector. A pneumatic test with soap suds shall be performed on each reinforcing pad at vessel openings (nozzles, manway’s, etc.), doubling plates on vessel supports and pads for lugs, etc. at 0.33 barg and shall be witnessed by the vessel certifying inspector. After testing the tell-tale holes shall be packed with grease. After final pressure testing all dimensions shall be measured and an "As built dimensional survey report" issued and countersigned by the inspector.

13.0

Painting Painting of Austenitic and Duplex Stainless steel surfaces is generally not required, unless the vessel is to be insulated.


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APPENDIX –A MINIMUM NUMBER OF EXPOSURES FOR X-RAY EXAMINATION OF CIRCUMFERENTIAL WELDS IN DUPLEX STAINLESS STEEL

For diameters < 90 mm and thickness < 8 mm the Double Wall - Double Image technique is applied (above the bold line in the table), the remainder Double Wall - Single Image. Code 2/3 means 2 exposures with ellipse projection or 3 exposures (optional if ellipse is not useful). * It may be practical to apply the Double Wall - Single Image technique also for 3" (88.9 mm) diameter welds. The minimum amount of exposures for this application is 6. Pipe Schedule " ½ ¾ 1 1¼ 1½ 2 2½ 3 *3 3½ 4 5 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36

mm 21.34 26.67 33.40 42.16 48.26 60.32 73.02 88.90 88.90 101.60 114.30 141.30 168.27 219.07 273.05 323.85 355.60 406.40 457.20 508.00 558.80 609.60 660.40 711.20 762.00 812.80 863.60 914.40

5S 2/3 2/3 2/3 2/3 2/3 2/3 2/3 2/3 6 6 6 6 6 6 6 6 6 6 5 5 5 5

10S 2/3 2/3 2/3 2/3 2/3 2/3 2/3 2/3 6 6 6 6 6 6 6 6 6 6 5 5 5 5

6

6

10

20

30

2/3 2/3 2/3 2/3 2/3 2/3 2/3 6 6 6 6

6 6 5 5 5 5 5 5 6 5 5 5

6 6 6 6 6 5 5 5 5 5 5 6 5 5 5

6 6 6 6 6 5 5 5 5 5 6 5 5 5


40S 3 2/3 2/3 2/3 2/3 2/3 2/3 2/3 7 7 7 8 6 6 6 6

S 3 2/3 2/3 2/3 2/3 2/3 2/3 2/3 7 7 7 8 6 6 6 6 6 6 5 5 5 5 5 5 6 5 5 5

40 3 2/3 2/3 2/3 2/3 2/3 2/3 2/3 7 7 7 8 6 6 6 6 6 6 5 5 5 5

60

6 8 8 6 6 5 5 5

80S 3 3 3 2/3 2/3 2/3 2/3 2/3 7 7 7 8 6 6 6 6

5 5 5

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XS 3 3 3 2/3 2/3 2/3 2/3 2/3 7 7 7 8 6 6 6 6 6 6 5 5 5 5 5 5 6 6 6 6

80 3 3 3 2/3 2/3 2/3 2/3 2/3 7 7 7 8 6 6 6 6 6

100

120

8 6

7 7 6 6 6

140

160 3 3 3 3 3 6 6 6 7 7 7 6

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XXS 3 3 10 8 8 8 8 8 7 7 7 7 7

" ½ ¾ 1 1¼ 1½ 2 2½ 3 *3 3½ 4 5 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36


APPENDIX- A MINIMUM NUMBER OF EXPOSURES FOR GAMMA-RAY EXAMINATION OF CIRCUMFERENTIAL WELDS IN DUPLEX STAINLESS STEEL

For diameters < 90 mm and thickness < 8 mm the Double Wall - Double Image technique is applied (above the bold line in the table), the remainder Double Wall - Single Image. Code 2/3 means 2 exposures with ellipse projection or 3 exposures (optional if ellipse is not useful). * It may be practical to apply the Double Wall - Single Image technique also for 3" (88.9 mm) diameter welds. The minimum amount of exposures for this application is 5. Pipe Schedule " ½ ¾ 1 1¼ 1½ 2 2½ 3 *3 3½ 4 5 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36

mm 21.34 26.67 33.40 42.16 48.26 60.32 73.02 88.90 88.90 101.60 114.30 141.30 168.27 219.07 273.05 323.85 355.60 406.40 457.20 508.00 558.80 609.60 660.40 711.20 762.00 812.80 863.60 914.40

5S 2/3 2/3 2/3 2/3 2/3 2/3 2/3 2/3 6 6 4 4 4 4 4 4 4 4 4 4 4 4

10S 2/3 2/3 2/3 2/3 2/3 2/3 2/3 2/3 6 5 4 4 4 4 4 4 4 4 4 4 4 4

4

4

10

20

30

2/3 2/3 2/3 2/3 2/3 2/3 2/3 5 5 4 4

4 4 4 4 4 4 4 4 4 4 4 4

4 4 4 4 4 4 4 4 4 4 4 4 4 4 4

4 4 4 4 4 4 4 4 4 4 4 4 4 4

40S 3 2/3 2/3 2/3 2/3 2/3 2/3 2/3 6 5 4 4 4 4 4 4

S 3 2/3 2/3 2/3 2/3 2/3 2/3 2/3 6 5 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4

40 3 2/3 2/3 2/3 2/3 2/3 2/3 2/3 6 5 4 4 4 4 4 4 4 4 4 4 4 4

60

4 4 4 4 4 4 4 4 4

80S 3 3 3 2/3 2/3 2/3 2/3 2/3 5 5 5 4 4 4 4 4

4 4 4

XS 3 3 3 2/3 2/3 2/3 2/3 2/3 5 5 6 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4

80 3 3 3 2/3 2/3 2/3 2/3 2/3 6 6 8 4 4 4 4 4 4 4 4 4 4 4

100

120

4 4 4 4 4 4 4 4 4

6 5 6 5 5 6 5 5 5 6 6 6

140

5 5 6 5 5 5 6 5 5

160 3 3 3 3 3 6 8 6 7 6 5 6 5 5 6 5 5 5 6 5 6

XXS 3 3 8 7 7 7 8 6 8 6 6 5 6 5 5 6

" ½ ¾ 1 1¼ 1½ 2 2½ 3 *3 3½ 4 5 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36

Application of this part of the table is not in accordance with the specification and requires BSP-approval


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REFERENCES: In this standard, reference is made to the following publications: BSP STANDARDS Document control procedure Piping classes Pressure testing of pipe work to ASME B31.3 for facilities design, construction and maintenance QA/QC in Facility Design, Construction & Maintenance Non-Destructive Testing Procedures

BSP-02-PRO-001 BSP-12-STD-102 BSP-12-STD-103 BSP-12-P-10 BSP-12-W-14

SHELL STANDARDS Index to DEP publications and standard specifications Definition of temperature, pressure and toxicity levels Welding of Metals (amendments/supplements to API RP 582) Acceptance criteria for oxidation of stainless steel weldments Pressure vessels (amendments/supplements to PD 5500) Pressure vessels (amendments/supplements to ASME VIII, Div 1&2) Piping general requirements Shop and field fabrication of steel piping Welded and seamless duplex and super duplex stainless steel line pipe Weldable structural steels for fixed offshore structures (amendments / supplements to BS 7191) Welding of pipelines and related facilities (amendments/supplements to ANSI/API STD 1104)

DEP DEP DEP DEP DEP DEP

00.00.05.05-Gen 01.00.01.30-Gen 30.10.60.18-Gen 30.10.60.31-Gen 31.22.10.32-Gen 31.22.20.31-Gen

DEP 31.38.01.11-Gen DEP 31.38.01.31-Gen DEP 31.40.20.34-Gen DEP 37.19.10.30-Gen DEP 61.40.20.30-Gen

AMERICAN STANDARDS Recommended practices for ultrasonic examination of offshore structural fabrication and guidelines for qualification of ultrasonic technicians Welding Guidelines for the chemical, oil and gas industries Welding of pipelines and related facilities Chemical plant and petroleum refinery piping Pipeline transportation systems for liquid hydrocarbons and other liquids Gas transmission and distribution piping systems Rules for construction of pressure vessels Qualification standard for welding and brazing Personnel Qualification and Certification in Non-Destructive Testing Mechanical testing of steel products Test method for Vickers hardness of metallic materials Macro-etching metals and alloys Test method for pitting and crevice corrosion resistance of stainless steel Structural Welding Code - Steel Specification for welding shielding gases


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API RP 2X

API 582 ANSI/API Std 1104 ANSI/ASME B31.3 ANSI/ASME B31.4 ANSI/ASME B31.8 ASME Sec VIII Div 1&2 ASME Sec IX ASNT RP SNT-TC-LA ASTM ASTM ASTM ASTM

A370 E92 E340 G48

AWS D1.1 AWS 5.3.2

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BRITISH STANDARDS Welding of steel pipelines on land and offshore Unfired fusion welded pressure vessels Fracture Mechanics toughness tests

BS 4515 BS PD 5500 BS 7448

INTERNATIONAL STANDARDS Quality systems-Model for quality assurance in production, installations and servicing Non-destructive testing – qualification and certification of personnel Steel and steel products – inspection documents Welding consumables – shielding gases for arc welding and cutting Petroleum and natural gas industries – Materials for use in H2S containing environments in oil and gas production.


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ISO 9001/9002 ISO 9712 ISO 10474 ISO 14175 ISO 15156

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APPENDIX B – Notice for Post-Weld Heat Treatment of Carbon Steel Piping -NOTEPost-weld Heat Treatment of Carbon Steel Piping Rev 0, 14 Jan 2009

INTRODUCTION This note gives notice of changes to document BSP-12-S-601, The Welding of Metals, with regards to the maximum permitted wall thickness for as-welded materials used for piping systems.

Post weld heat treatment (PWHT) is applied to steel assemblies primarily to reduce the risk of brittle fracture by reducing the level of tensile residual stresses and by tempering hard, potentially brittle, microstructural regions. Whether PWHT is necessary depends on the fracture toughness, the stress levels and the size of any flaws which may be present.

MATERIALS The revised conditions given herein are applicable for carbon steel materials complying with ASME IX groups P1 or A1. All other materials shall require PWHT as per ASME B31.3.

CURRENT LIMITATIONS As per BSP-12-S-601 and under clause 331.1 of ASME B31.3, the following statement is made:

“If the parent material conforms to Group P1 or A1 and has a certified restricted Carbon content of less than 0.23% and a carbon Equivalent of less than 0.42% then a PWHT shall not be required when the weldment has a through thickness of less than 35mm. This statement is only valid if the minimum design temperature is equal to or greater than 0 degrees centigrade. If the design criterion is not fulfilled, then the code requirements (19.5mm) shall be utilised in determining whether PWHT is required or not”.

REVSIED LIMITATIONS For the reasons given below the above statement is no longer supported. From the date of this note the following statement shall be true and replace the above statement in BSP-12-S-601.

All carbon steel materials with a weld through thickness of >19.5mm shall require PWHT in accordance with code (ASME B31.3). Should exemption or relaxation be sought from this clause the fabricator / contractor shall apply the principles of an Engineering Critical Assessment, on a case-by-case basis and using fracture mechanics, to demonstrate that PWHT can be waived without determent to the weld properties or performance in service.


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DISCUSSION The current statement made in BSP-12-S-601 originates from a the superseded revision of API 582 which was amended by DEP 30.10.60.18-Gen. The latest revision of this DEP does not make such a statement. In addition to aligning BSP practices with that of the wider Shell Group, the following technical points support the revised limitations given above.

The limitations placed on the chemical composition of piping components is an attempt to avoid the formation of hard brittle zones or cracks which could act as initiation sites for fracture. There is no explicit link to fracture toughness.

The generalisation of the material groups implied under the current clause i.e. all P1 materials is not justified. Under ASME IX, the P1 group has in the region of 175 different material grades all with slightly different chemical composition limits and toughness properties. Of course our MESC codes limit some of this variability but not enough to allow the current relaxation.

The somewhat lower threshold thickness of ASME B31.3 compared to other similar codes, for example EEMUA 158, can in some way be linked to the greater likelihood of defects going undetected when only a % of welds are subject to NDT like is the case for piping fabricated in accordance with ASME B31.3. The maximum permitted defect is directly linked to the fracture toughness.

During design of piping systems for BSP projects the general approach is to assume that PWHT is carried out above 19.5mm as per code requirements and hence residual stresses reduced.

Bruce Cowe SEN/641 14/01/2009.

References: 1.

TWI report 791A/2004: Towards exemption from post weld heat treatment of C-Mn and low alloy steels, October 2004.

2.

BSP-12-601, rev 2.0: The Welding of Metals.

3.

API RP 582: Welding Guidelines for the Chemical, oil and Gas Industries, First Edition, March 2001.

4.

DEP 30.10.60.18-Gen: Welding of Metals (Amendments/Supplements to API RP582), May 2004.

5.

ASME B31.3: Process Piping.

-END-


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174701442 BSP 12 Standard 601 Rev 3 0 the Welding of Metals PDF

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