Welding of Duplex Stainless Steel Pipelines

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Specification Specification for Welding of Duplex Stainless Steel Piping

Contents 1. Introduction ..................................................... ........................................................... ......... 1 1.1 Purpose................................................................ ......................................................... .... 1 1.2 Changes to the Specification................ ...................................................................... ...... 1 1.3 Effective Period .............................................................. ................................................. 1 1.4 Review and Improvement ........................................................... ..................................... 1 1.5 Process Owner's Responsibility ............................................................. .......................... 1 2. Specification for Welding Duplex Stainless Steel.............................................................. 2 2.1 Specification Requirements ........................................................ ..................................... 2 2.2 Process Deliverables ........................................................... ............................................. 2 2.3 Performance Levels / Indicators ............................................................ .......................... 2 2.4 Performance Monitoring ............................................................ ...................................... 2 Appendix A Glossary of Definitions, Terms and Abbreviations........... ............................... 3 Appendix B Amendments/Supplements to ASME B31.3 ..................................................... 6 Chapter V Fabrication, Assembly and Erection ................................................................. .. 6 328 Welding ....................................................... ................................................................ .... 6 328.2 Welding Qualifications ...................................................................... ................... 6 328.2.1 Qualification Requirements............................................................................. 6 328.2.1.1 General......................................... ........................................................ 6 328.2.1.2 Welding Procedure Specification ........................................................ 6 328.2.1.3 Essential Variables......................................... ...................................... 7 328.2.1.4 Test Welding................ ................................................................ ........ 8 328.2.1.5 Examination of the Test Weld ........................................................... 10 328.2.1.6 Destructive Testing of the Test Test Weld Weld ................................................ 10 328.2.1.7 Retests.................................................................. Retests... ............................................................... .............................. 13 328.2.1.8 Approval of the WPS..................... .................................................... 13 328.2.1.9 Performance Qualification ................................................................. 13 328.2.2 Procedure Qualification by Others...... Others................................................................ .......................................................... 14 328.2.3 Performance Qualification by Others............................................................ 14 328.2.4 Qualification Records............................................................................. ....... 14 328.3 Welding Materials ................................................................ .............................. 15 328.3.1 Filller Metal...................................................... ............................................. 15 328.3.1.1 Storage and Handling of Filler Metals Metals and Fluxes ............................ 15 328.3.1.2 Shielding Gases......................................................................... ......... 16 328.3.2 Weld Backing Material .................................................................. ............... 16 328.3.3 Consumable Inserts .............................................................. ......................... 16 328.4 Preparation for Welding ............................................................ ......................... 16 328.4.1 Cleaning ......................................................... ............................................... 16 328.4.2 End Preparation......................... ........................................................... ......... 16 328.4.3 Alignment................................................................... ................................... 17 328.5 Welding Requirements ........................................................... ............................ 18 328.5.1 General.................................................... General .................................................... ...................................................... 18 328.5.2 Fillet and Socket Welds ........................................................ ........................ 20 328.5.4 Welded Branch Connections..................... .................................................... 21 328.6 Weld Repair ......................................................... ............................................... 21 328.6.1 General.................................................... General .................................................... ...................................................... 21 328.6.2 Welding of Test Repair Welds...................................................................... Welds.... .................................................................. 22 328.6.3 Testing of Repair Welds ................................................................ ............... 22 330 Preheating .............................................................. ....................................................... 22 330.1 General.......................................................... ...................................................... 22

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330.1.1 Requirements and Recommendations............................................................22 330.1.4 Preheat Zone..................................................................................................22 330.2 Specific Requirements ................................................................ ........................ 23 330.2.4 Interrupted Welding ........................................................ .............................. 23 331

Heat Treatment ........................................................ .................................................... 23

332 Bending and Forming ............. ................... ............. ............. ............. .............. ............. ............. ............. ............. ............. ............. ............. .............23 .......23 332.1 General................................................................................................................23 333

Brazing and Soldering..................................................................................................23

336 Handling and Storage ............. .................... ............. ............. .............. ............. ............. .............. ............. ............. .............. .............. ............. ...........23 .....23 336.1 General................................................................................................................23 336.2 Storage .................................................... ............................................................ 24 336.3 Pipe Handling......................................................................................................24 Chapter VI Inspection, Examination and Testing ............................................................... 25 340 Inspection......... tion............ ...... ....... ....... ...... ....... ....... ...... ....... ....... ...... ....... ....... ...... ...... ....... ....... ...... ....... ...... .. Error! Bookmark not defined. 340.4 Qualifications of the Owner’s Inspector ............. Error! Bookmark not defined. 341 Examination............... ination...................... ............. ............. .............. ............. ............. .............. ............. ............. .............. ............. ............. .............. ............. ............25 ......25 341.2 Responsibility for Examination...........................................................................25 341.3 Examination Requirements .................................................................... ............. 25 341.3.1 General ........................................................ .................................................. 25 341.3.2 Acceptance Criteria ................................................................ ....................... 25 341.4 Extent of Required Examination.........................................................................25 341.4.1 Examination Normally Required...................................................................25 342 Examination Personnel Personnel ............. .................... ............. ............. .............. ............. ............. ............. ............. .............. ............. ............. .............. ..........26 ...26 342.1 Personnel Qualification and Certification Certification ........................................................... 26 343

Examination Procedures..............................................................................................26

344 Types of Examination Examination ............. .................... .............. ............. ............. .............. ............. ............. ............. ............. .............. ............. ............. ............27 .....27 344.2 Visual Examination.............................................................................................27 344.2.2 Method...........................................................................................................27 344.3 Magnetic Particle Examination .............................................................. ............. 27 344.4 Liquid Penetrant Examination.............................................................................27 344.5 Radiographic Examination..................................................................................27 344.5.3 Method...........................................................................................................27 344.6 Ultrasonic Examination.......................................................................................28 345 Testing ............. ................... ............. .............. ............. ............. .............. ............. ............. ............. ............. .............. ............. ............. .............. ............. ............. ...........28 ....28 345.1 Required Leak Test ......................................................... .................................... 28 346 Records.................. ds......................... ............. ............. .............. ............. ............. .............. .............. ............. ............. .............. ............. ............. .............. ............. ..........28 ....28 346.1 Documentation ............................................................ ........................................ 28

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Specification Specification for Welding of Duplex Stainless Steel Piping

Certificate of Conformity ........................................................ .................................... 29

Table 1 Extent of Non-Destructive Testing for Welds ........................................................ 30 Figure 1

Hardness Indent Locations .................................................................. ............ 32

Figure 2

Orientation Orientation and Location Location of Charpy Impact Specimens Specimens ............. ................... ............. ........... .... 33

Appendix C References.............................................................................. ............................ 34 Appendix D Determination of the Volume Fraction of Ferrite in Duplex Duplex Stainless Steel by Systematic Point Count ......................................................... ............................................ 36 Appendix E Certificate of Compliance.............. ................................................................ ... 40 User Comment Form ....................................................... ....................................................... 41

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1.

Introduction

1.1

Purpose

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This specification is a revision of SP-1096 version 1.0, Specification for Welding of Duplex Stainless Steel Piping, issued issued in July 1999. The purpose of this document is to define define the minimum technical requirements for the welding of duplex stainless steel (DSS) pipework. This specification is intended to be used where the applicable code has been designated by the Company as ASME B31.3, 2002. Chemical Plant and Petroleum Company Piping, (normally on-plot locations). This document is not applicable to the welding of DSS pipelines, where the applicable code has been designated as ASME B31.4 or ASME B31.8 (off-plot locations) or to the manufacture of welded DSS pipe

1.2

Changes to the Specification This Specification shall not be changed without approval from the Custodian, the Material and Corrosion Functional Functional Discipline Head Head (CFDH) (CFDH) who owns this Specification. If you think the Specification is not correct, write your comments on a copy of the User Comments Form. The form is included as the last page of this Specification. Specification. Send the copy with your comments and personal details to DCS.

1.3

Effective Period The requirements of this specification shall remain in force indefinitely unless superseded by an authorised revision.

1.4

Review and Improvement This specification will be reviewed reviewed and updated once every three years. The review authority will be CFDH Materials and Corrosion.

1.5

Process Owner's Responsibility The owner of this specification is CFDH Materials and Corrosion, is responsible for authorising all proposed deviations or amendments to the specification and for the instigation of periodic reviews and updates in accordance with Clauses 1.2 and 1.4.

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2.


Specification for Welding Duplex Stainless Steel This specification gives the minimum requirements for the welding, fabrication and inspection of duplex stainless steel on-plot pipework. The scope is intended to cover all commercially available compositions (MESC), including 22Cr and 25Cr duplex/superduplex grades. The specification is restricted to piping for service in non-sour environments where the applicable Code for pressure piping is designated by the Company as ASME B31.3, Chemical Plant and Petroleum Refinery Piping. The use of duplex stainless materials in environments containing H2S shall be subject to approval by the Company.

2.1

Specification Requirements Welding, fabrication and inspection shall be in accordance with the requirements of ASME B31.3, 2002 Edition, as amended and supplemented by Appendix B of this specification. The amendments and supplements given in Appendix B are considered necessary to ensure integrity of the fabricated pipework in accordance with PDO and Shell Group requirements. The Clause numbering in Appendix B follows that of ASME B31.3. Where clauses of ASME B31.3 are not amended or supplemented by Appendix B, they shall apply in their entirety.

2.2

Process Deliverables Process deliverables comprise shop or field welded duplex stainless steel pipework and related welded fabrications designed to ASME B31.3 and normally intended for on-plot oil, gas or water service.

2.3

Performance Levels / Indicators See relevant ASME B31.3 weld inspection and testing acceptance criteria and the amendments given in Appendix B of this specification.

2.4

Performance Monitoring Requirements for monitoring welding process variables, welder performance and weld quality are detailed in relevant sections of ASME B31.3/ASME IX as amended by Appendix B of this specification.

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Appendix A Glossary of Definitions, Terms and Abbreviations Certain terms and abbreviations used in this document are defined below. The listed definitions shall be considered to supplement those given in ASME B31.3.

General Definitions Contractor

Manufacturer/ Supplier

The party which carries out all or part of the design, engineering, procurement, construction, commissioning or management of a project, or operation or maintenance of a facility. The Company may undertake all or part of the duties of the Contractor. The party which manufactures or supplies equipment and services to perform the duties specified by the Contractor.

Company

Petroleum Developmant Oman LLC. The Company will generally specify the technical requirements. The Company may also include an agent or consultant authorised to act for, and on behalf of, the Company.

User

The Company, Consultant or Contractor who uses this document.

Corporate Functional Discipline Head

The person within the Company responsible for the discipline to which the standard belongs.

shall

Indicates a requirement. Any deviation to a requirement shall be approved by the CFDH.

should

Indicates a recommendation. A deviation to a recommendation shall be approved by the welding (TA-2).

may

Indicates a possible course of action.

Specific Definitions Batch or Lot (see App. B, 328.3.1)

As defined in AWS A5.01, Clause 5 (Classification) and Clause 6 (Testing)

Duplex Stainless Steel

A chromium-nickel-molybdenum stainless steel containing a balance of austenite and ferrite stabilising alloying elements such that the microstructure at room temperature consists of approximately equal proportions of austenite and ferrite.

Nominal Thickness

Nominal thickness t shall have the following meanings: - butt joint; parent metal thickness, which for joints between dissimilar thicknesses is that of the thinner material. - fillet weld; parent metal thickness, which for joints between dissimilar thicknesses is that of the thicker material. - set-on branch connection; thickness of branch pipe - set-through branch connection; thickness of main pi pe.

Owner

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Term used in ASME B31.3 that shall be understood to mean the Company.

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Verified copy

Welding Co-ordinator

A photocopy of an original document which has been reendorsed and signed by the organisation producing the photocopy to verify that none of the information has been adulterated. The Contractor nominated authority on the quality aspects of welding. The Welding co-ordinator shall be a Welding Engineer meeting the recommendations for European Welding Engineer (refer ISO 14731). However, other national/ international qualifications may be considered at the discretion of the Company. The Welding Co-ordinator shall be approved by the Company TA-2 (Welding).

Abbreviations a

Throat Thickness of Fillet Weld

ASNT

American Society for Non-destructive Testing

CFDH

Corporate Functional Discipline Head

AWS

American Welding Society

CSWIP

Certification Scheme for Welding Inspection Personnel

D

Nominal Outside Diameter

DSS

Duplex Stainless Steel

DNV

Det Norske Veritas

GTAW

Gas Tungsten Arc Welding

IQI

Image Quality Indicator

HAZ

Heat Affected Zone

HV

Vickers Hardness

NDE

Non-destructive Examination

PAMS

Portable arc monitoring system

PQR

Procedure Qualification Record

PRE

Pitting Resistance Equivalent

PT

Penetrant Testing

PWHT

Post Weld Heat Treatment

RT

Radiographic Testing

SAW

Submerged Arc Welding

SMAW

Shielded Metal Arc Welding

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T

Nominal Thickness

TA

Technical Authority, as defined in ERD-00-02 and PDO GU-272.

TWI

The Welding Institute

WPS

Welding Procedure Specification

WFS

Wire Feed Speed

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Appendix B Amendments/Supplements to ASME B31.3 Chapter V Fabrication, Assembly and Erection 328

Welding Delete introductory paragraph and replace as follows: Welding shall be performed in accordance with the requirements of ASME B31.3 and the amendments and additions of this specification. The work shall be undertaken only by Contractors that have been approved by the Company specifically for the on-plot welding of duplex stainless steel, (Work Category CE6421). Approval of Contractors shall be based on Company document GU-225. The welding Contractor shall maintain and operate a quality system that shall be in accordance with ISO 9001:2000, and SP-1171. A quality system based on alternative standards to of ISO 9001 may be considered for agreement by the Company. All welding and related activities shall satisfy the requirements of ISO 3834-2. It is recommended to follow the guidelines given in PD CR 13576.

328.2

Welding Qualifications

328.2.1 Qualification Requirements Delete entire section and replace as follows:

328.2.1.1

General

Where the Contractor is unable to provide satisfactory records to demonstrate the suitability of the proposed welding procedure specification and compliance with ASME B31.3 and this specification, welding procedure qualification shall be undertaken prior to the commencement of production welding. The Contractor shall submit WPS proposals to the Company for review and approval a minimum of two weeks prior to undertaking qualification welding. The WPS proposals shall be endorsed by the Contractor's Welding Engineer. A Welding Procedure Register shall accompany the package. This shall list and identify all WPS/PQRs intended to be used for the contract, detailing as a tabulated summary welding processes, materials and qualified dimensional ranges. The qualification of dissimilar welds, between duplex stainless steel and other material groups, shall be in general accordance with this specification, except that welding consumables and specific test requirements will be agreed by the Company Welding TA - 2 (or higher) for each application. Note: Any welding procedure qualified to meet project specific requirements for which the Company has paid/reimbursed the cost of qualification shall be owned by the Company. The Company will keep original PQR copies.

328.2.1.2

Welding Procedure Specification

The format of the WPS shall be equivalent to form E00006, shown as QW-482 in Appendix A of ASME IX, and shall contain the following applicable parameters, including explanatory details where necessary. •

Material specification of base metals.

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• • • • • • • • • • • • • •

• • • • • •

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Welding process and whether manual or automatic. Wall thickness and diameter range for which the procedure is valid, (see 328.2.1.3 (c) and (d)). Geometry of the welding groove showing allowable tolerances. Root gap showing allowable tolerances. Welding position and direction. Filler metal specification and diameter. Filler metal classification and coating type. Specification of flux. Tungsten electrode type and specification. Gas shielding flow and composition. Gas backing flow and composition Number of weld passes for which gas backing is required. Number and sequence of all passes, indicating stringer or weave beads. For automatic welding the weave amplitude, weave frequency and dwell time shall also be included. Welding current range, voltage range and polarity. If pulse welding is used, the background current and range of pulse parameters or unique program reference to be included. Where applicable, electrode stick-out and WFS range. Travel speed range for each pass. Heat input range. Preheat and interpass temperatures. Methods of joint preparation interpass cleaning and weld finishing. Method of clamping/tacking, including details of removal

Test welding shall not commence until the WPS proposal has been stamped 'Approved for Qualification' with the date and the contract number, and signed by a Company welding TA-2.

328.2.1.3

Essential Variables

When changes in any of the parameters listed below are made beyond the indicated limits, the welding procedure shall be set up as a new WPS and shall be completely re-qualified. (a) Welding process

A change to another welding process or a change from manual to automatic operation or vice versa.

(b) Base materials

Any change in UNS number. A change in the PREN exceeding –1.5 or +2.5. For super-duplex grades any change in manufacturer or product form shall be considered an essential variable. A procedure qualified by welding together products from different manufacturers or different product forms shall qualify both the combination and welds between each product..

(c) Thickness

For t > 5mm, a change in thickness at the joint outside the range 0.75t to 1.5t, but not < 5mm. For t < 5mm,a change outside the range t to 1.5t. For a fillet weld, in addition to material thickness, a change in throat thickness outside the range 0.75a to 1.5a. (See Appendix A of this specification for definitions of t).

(d) Diameter (D)

Change in pipe or branch diameter outside the following ranges: D <323mm; 0.5D to 2D D ≥ 323mm; 0.5D to maximum to be welded.

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(e) Joint design (f) Welding position

Any change in joint configuration outside the specified tolerance. Any change, except that, subject to the approval of the Company Welding TA-2, qualification of a joint in the fixed 45° inclined (6G) position shall qualify for all positions.

(g) Welding progression

A change from uphill to downhill or vice versa.

(h) Filler metal/electrode

Any change in electrode/filler metal classification or trade name, except that for solid filler wire, a change to a different trade name may be accepted without requalification subject to the approval of the Company Welding TA-2. Any change in electrode or filler wire diameter.

(i) Flux

Any change in size, classification or trade name.

(j) Shielding or backing gas

A change in nominal flow rate of more than ±20%. Any change in nominal composition of shielding or backing gas. Any increase in maximum oxygen content of effluent backing gas.

(k) Number and sequence of passes

Any change in the 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.

(l) Electrical characteristics

A change of more than ±15% in the individual values for volts, amps and wire feed speed determined from the PQR. Changes in individual parameters and of welding speed, (clause (m)), shall be controlled such that heat input is maintained within the permitted range of clause (n). A change of electrode polarity or current type, including the addition or deletion of pulsating current.

(m) Speed of travel

Any change greater than ±15%.

(n) Heat input

Any change in average welding heat input per pass outside the range ±10% of that qualified.

(o) Preheat or interpass temperature

An increase of more than 50°C in the specified minimum preheat temperatures or any increase in maximum interpass temperature.

(p) Post-weld heat treatment

The inclusion or deletion of PWHT or any change in PWHT parameters.

328.2.1.4

Test Welding

Sufficient test welds shall be made to extract all the destructive test specimens required for qualification testing. Test welding shall be witnessed by the Company Welding TA-3. The Contractor shall give the Company a minimum of 48 hours notice of the intention to proceed with test welding.

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The Contractor shall have a minimum of one Company-approved calibrated portable arc monitoring system with hard copy facility available at the test site to record welding parameters. No test welding is permissible without recording the welding parameters using a calibrated portable arc monitor . Prior to the commencement of test welding, the Contractor shall have available at the test site the following documents for verification by the Company: • • • •

Original copy of the WPS proposal, endorsed ‘Approved for Qualification’ Material certificates or verified copies, traceable to the items to be welded. Batch certificates or verified copies, traceable to the welding consumables, (see 328.3.1). Approved consumable handling procedure.

Test welding shall not commence until the Company has reviewed and accepted the documentation. All test welding shall be witnessed by a Company representative having a Welding Technical Authority level 3 or higher. The Contractor’s Welding Coordinator who is approved by the Company shall supervise the entire welding procedure qualification process. The Contractor shall be responsible for examination and shall have a Company approved welding examiner (Welding Inspector) present throughout test welding and NDE of the welds. NDE shall be performed only by Company registered NDE subcontractors in accordance with SP-1176. The test weld shall simulate as closely as possible the actual production environment and welding set-up used, including as applicable, clamping, support and back purging arrangements. The longest length of internal purge tubing expected to be required for use with the procedure should be included in the test set-up to confirm that the required purging conditions can always be attained and monitored without affecting weld quality. Set-up details shall be recorded in the test welding record. In order that root oxidation can be assessed under ‘worst case’ conditions, welding should commence as soon as the maximum specified back purge oxygen level is reached. The following information shall be recorded for each pass of the test weld and shall form part of the PQR: • • • • • • • • • • • • • •

Pass number Welding process Consumable diameter Consumable trade name and classification (including flux for SAW) Electrode polarity Gas composition Gas flow rate Arc voltage Current Wire feed speed Travel speed Preheat temperature Interpass temperature Pass sequence

The test weld information shall be recorded on welding parameter sheets which shall be attached to the completed form E00007, shown as QW-483 in Appendix A of ASME IX. Pass sequence shall be shown in the sketch on the ASME form. The Approved for Qualification WPS, original or verified copies of the test coupon material and consumable batch test certificates and the original PAMS unit printout shall be included as part of the PQR. The welding records of the test welding shall be signed, dated, and endorsed by the Contractor's welding examiner (Welding Inspector) and the Company welding TA-3 present at the time of test welding.

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If post weld heat treatment is required, a heat treatment record chart shall be produced and shall be endorsed by the Contractor, the heat treatment sub-contractor (if applicable), and the Company Welding TA-3 present during heat treatment. The chart shall be included in the PQR.

328.2.1.5

Examination of the Test Weld

NDE shall be witnessed by a Company Welding TA-3 (or higher) or by a Third Party Inspector nominated by the Company. The NDE shall consist of the following: • • •

Visual examination Liquid penetrant testing Radiographic testing

NDE on all test welds shall be performed with the weld at ambient temperature using equipment and Company-approved procedures that will be employed for production. NDE of a test weld may serve as a qualification test for the NDE procedures. The acceptance criteria shall be as stated in Chapter VI of ASME B31.3 and the corresponding sections of this specification. Any weld that 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. The radiographic report shall be signed by the technician and th e Contractor's welding examiner prior to presenting the radiographs to the Company Welding TA-3 with interpretation qualification for viewing. After viewing, the Company Welding TA-3 shall sign and endorse the radiographic report and it shall be incorporated into the PQR.

328.2.1.6

Destructive Testing of the Test Weld

Testing for procedure qualification shall be performed in accordance with ASME IX and the additional requirements in Paragraphs (a) to (f), following. The Contractor shall appoint a Company-approved agency to witness the destructive testing. This agency shall certify that all tests are made in accordance with the controlling specifications. The Company shall have the option to witness the destructive testing or to appoint an agency to act on its behalf. All test reports shall be endorsed and signed by the testing o rganisation, the Contractor, and the third party inspector who witnessed the testing. The test reports shall be included in the PQR. (a) Macro-examination Two macro-sections shall be taken from a butt weld in pipe at the 12-1 o'clock and the 6-7 o'clock positions. Where two welders have made the joint, the macro specimens shall be taken from the specified positions such that each welder's portion is sampled. For branch welds, four macro-sections shall be taken at 90° intervals through the centre of the joint, in line with the longitudinal or transverse axis of the run pipe. Specimens shall be prepared for macroscopic examination by grinding or other suitable method to a 600 grit paper finish. The prepared surfaces shall be etched using a suitable etchant to reveal the pass sequence, HAZ, defects etc. Metallographic examination of representative sections shall also be performed to confirm the microstructure of the weld/HAZ and the absence of deleterious phases. Observations shall be included with the macroscopic examination report Macro-examination shall be carried out at a minimum magnification of x5. The acceptance criteria shall be as detailed in chapter VI of ASME B31.3 and shall include

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measurements for height of reinforcement and internal protrusion. Following the hardness measurements detailed below in paragraph 328.2.1.6(b), macrophotographs shall be produced for inclusion in the PQR. (b) Hardness survey For pipe, a hardness survey shall be performed on each macrosection. The hardness, shall be measured in accordance with ASTM E92 using a 10 Kg load. For pipe butt welds, the hardness indentations shall be as shown in Figure 1 of this specification and shall be clearly visible in the macrophotographs. For pipe of t less than 10 millimetres, the mid-thickness traverse may be omitted. One indent of each HAZ set of three shall be as close to the fusion line as possible but shall not intercept it. The sections of the weld taken for macroscopic examination and hardness testing shall also be used for the ferrite measurements required in the following clause, 328.2.1. 6(c). The maximum hardness values from each traverse shall not exceed 325 HV10. (c) Ferrite measurement The ferrite content shall be determined by microscopic point counting in accordance with ASTM E562 and Appendix D of this specification, For DSS, a magnetic measurement technique using an instrument calibrated to AWS 4.2 may be used. Ferrite determinations shall be made in the weld metal and both HAZ areas at a depth of 1mm from the inside and from the outside surfaces, or for magnetic techniques, as close to the surface as is practicable. Additional checks shall be made in the centre of the unaffected base material on each side of the weld. Ferrite content determined by microscopic point counting shall be in the range 40 - 6 0% for the parent material and 35 - 65% in the weld/HAZ regions. The ferrite range for magnetic measurements shall be between 30 – 70 FN. In the event that borderline unacceptable or otherwise doubtful results are obtained using magnetic measurement, a check point-counting determination may be made if agreed by the Company Welding TA-2. If the results of these repeat tests are satisfactory, the ferrite content shall be considered to be acceptable. (d) Charpy V-notch impact tests Each procedure qualification shall include impact testing unless the nominal pipe wall thickness is less than 4.8 mm. The sampling area of the weld shall be as shown in Figure QW-463.1(f) of ASME IX. One set of three specimens shall be taken at each of the following positions: • root weld centre line • root fusion line (50% intersection of notch) • root fusion line + 2 millimetres

When the wall thickness exceeds 20 millimetres, an additional set of three specimens shall be taken at each of the following positions: • cap weld centre line • cap fusion line (50% intersection of notch) • cap fusion line + 2 millimetres

These requirements are summarised in Figure 2 of this specification.

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Specimens shall be 10 x 10 millimetres full size wherever possible. Where these dimensions are not possible, the largest obtainable standard sub-size specimens shall be extracted. Testing in accordance with ASTM A370 and this specification shall be conducted at minus 20°C or at the minimum design temperature, whichever is the lower. The test temperature shall remain the same for all specimen thicknesses. For each set of three specimens, only one of the individual values may be below the minimum average energy requirement with an absolute minimum as defined by the minimum individual acceptance criterion. The acceptance criteria are detailed in the Table below. For other standard specimen dimensions, the acceptance criteria shall be applied pro rata.

Specimen size, mm

10 x 10 10 x 7.5

Charpy Energy, Joules Minimum Average 40 30

10 x 5

Minimum Single 30 23

20

15

(e) Corrosion testing A pitting corrosion resistance test shall be conducted in accordance with ASTM G48, Method A, using the total immersion ferric chloride test. A coupon specimen of dimensions 5 cm x 5 cm x full wall thickness shall be prepared to the requirements of ASTM G48, Section 5. No flattening of the coupon material shall be carried out. The weld seam shall be located centrally and parallel to one axis. The edges of the specimen shall be rounded to minimise edge effects and the sides ground to 600 grit finish. Other surfaces shall be in the "as-finished" condition. The specimen shall be degreased, dried, weighed to three decimal places and the weight recorded. The specimen shall be held in the solution at an angle of 45°, with inside surface uppermost. Unless otherwise directed, the test shall be conducted for a period of 24 hours at a temperature of 22°C ± 2°C. For the higher alloyed 25Cr duplex/superduplex grades the test temperature shall be 3 5-37ºC unless otherwise specified On completion of the test period the specimen shall be rinsed, cleaned, dried and reweighed using the procedures specified in ASTM G48A. The specimen shall be examined at a magnification of x20. No pitting shall be visible. Weight loss shall be expressed as total weight loss and weight loss per unit area. The latter shall not exceed 8g/m2. All samples shall be made available for in spection by the Company. (f) Chemical analysis Chemical analysis shall be conducted of the root run weld metal. The weld metal sample shall be taken from an adjacent or equivalent location to that shown for the impact test specimens in Figure A. The elements required for calculation of the PRE (see Section 328.3.1) shall be determined. The PRE value shall exceed the minimum specified for the base material to be welded.

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328.2.1.7

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Retests

With the exception of Charpy tests and hardness tests, if any one mechanical test specimen fails to meet the minimum requirements, two additional test specimens shall be extracted and tested. The Contractor shall notify the Company of the test failure and obtain written Company approval to proceed with retests. If both of the retests are acceptable that particular test shall be deemed as acceptable. Should one or both of the retests fail then the procedure shall be rejected immediately. For hardness tests, 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 of the further tests are below the maximum specified hardness the test shall be accepted. The Contractor shall notify the Company of the test failure and obtain written Company approval to proceed with retests 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. Retesting of any corrosion specimen which fails to meet the pitting and/or weight loss acceptance criteria in the ASTM G48A corrosion test shall be permitted only if failure can be reasonably attributed to test conditions or sample preparation. Where retesting is agreed by the Company, two further specimens shall be prepared and tested. Both of the additional specimens shall meet the acceptance criteria. If the test joint fails to meet the minimum requirements, a new WPS proposal shall be established and qualification welding and testing repeated.

328.2.1.8

Approval of the WPS

Subsequent to successful non-destructive and destructive testing, the Contractor shall submit the original PQR showing endorsement and signatures of the Contractor, the testing subcontractor, and the Company. The Contractor shall also submit a copy of the WPS to be used for production welding and, if necessary, a revised welding procedure register for review and approval by a Company Welding TA level 2 or higher. Production welding shall not commence until the WPS has been endorsed 'Approved for Fabrication' with the date and the contract number, and signed by a Company welding Technical Authority level 2. Only those WPSs shown on the approved WPS register shall be used in production.

328.2.1.9

Performance Qualification

Welders and welding operators shall be qualified in accordance with the requirements of ASME IX and of this specification. For Super DSS any change which necessitates requalification of the WPS shall also require requalification of the welder. For DSS, the following essential variables shall be applied for welder qualification: (a) A change in joint thickness to more than twice the thickness of the test joint. (b) A change in pipe or branch diameter outside the range 0.5D to 2 D, where D is the test pipe diameter. (c) A major change in joint configuration, e.g. ‘U’ to ‘V’ preparation (d) A change in welding progression from uphill to downhill or vice versa. (e) For manual welding electrodes, a change from one coating type to another (f) Any change in the nominal composition of the shielding gas.

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Welders shall have a valid Company qualification within the validity defined in this specification or they shall be qualified on contract materials using a WPS endorsed ‘Approved For Fabrication’. A calibrated portable arc monitor shall be used to record welding parameters. Qualification shall be valid for a period of six months. This period may be extended by a further six months when it can be shown by NDT from production welding that the welder has produced satisfactory welds using the approved for construction WPS. After 12 months the welder shall be re-qualified, unless otherwise agreed by th e Company Welding TA-2. The Company reserve the right to disqualify any welder whose performance during production welding is not satisfactory. The Company shall be given a minimum of 48 hours notice of intention to perform welder qualification in order to witness the test welding. Welding and testing shall be witnessed by a Company Welding TA-3. Butt weld test pieces shall be subjected to visual examination, radiography, bend testing and macroscopic examination to the requirements of ASME IX, QW-302 and this specification. A welder who fails to meet the acceptance criteria shall be allowed an immediate retest. A welder who fails to meet the acceptance criteria after the first retest shall not be allowed a second retest within seven days. The Contractor shall demonstrate that the welder has undergone training in that period. Failure to demonstrate training shall prevent the welder from being retested. Should the second retest fail then that welder shall be disqualified for the duration of the contract. Performance qualification data shall be recorded by the Contractor on ASME form E00008 (QW-484) or other format agreed by the Company. The ASME form shall then be endorsed and signed by the Contractor and the Company Welding TA-3 who witnessed the test welding. The completed record forms shall be submitted to the Company Welding TA-3 who shall issue a welder's card which shall show the WPS for which the welder is qualified, the welder's unique identification, and the Company TA-3 signature and endorsement. The welder shall maintain the card in his possession at the job site and shall produce it upon request by the Company. Failure to produce the card shall prevent the welder from welding until such time as it is produced. The card shall be the property of the Company and shall be revocable by the Company. The Contractor shall assign an identifying number, letter, or symbol to the qualified welder which shall be used 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.

328.2.2 Procedure Qualification by Others Delete section and replace as follows: Procedure qualification by others, as defined in ASME B31.3 shall not be permitted.

328.2.3 Performance Qualification by Others Delete section and replace as follows: Performance qualifications made for another employer shall not be accepted.

328.2.4 Qualification Records Delete section and replace as follows: See sections 328.2.1.2, 328.2.1.4 and 346.1 of this specification.

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Welding Materials

328.3.1 Filller Metal Add the following, including new sub-sections 328.3.1.1 and 328.3.1.2: Only consumables from Company approved suppliers shall be used. Approval shall include the manufacturing plant and shall be verified by a third party inspection agency. Each batch of consumables shall be tested in accordance with the AWS procedures specified for the consumable classification. The tests shall be conducted with third party witness and verification at a Company approved facility. Batch testing is required, irrespective of whether the consumables are supplied with a verified copy of the Supplier’s/Manufacturer's batch certificate. The definition of a batch is given in Appendix A of this specification. All filler metals shall have classification society, (e.g., Lloyd's, DNV), type approval. Filler metals should be of matching specification to the base material to be welded with the exception of the following: • •

The chromium and nickel contents of each batch should be equal to or higher than those of the filler used in the corresponding procedure qualification test. The PRE of the filler metal, as calculated from the batch test certification on the basis defined below, should be at least 2 units higher than the minimum specified PRE of the base material to be welded. PRE = (%Cr) + 3.3(%Mo + 0.5%W) + 16(%N)

NOTE: Tungsten (W) analysis need be considered only if specified as an alloying addition.

328.3.1.1

Storage and Handling of Filler Metals and Fluxes

Electrodes, filler wires and fluxes shall be 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 job site to the satisfaction of the Company. The storage room should be maintained at a maximum relative humidity of 50%, which shall be monitored in accordance with an agreed procedure. Consumables delivered in containers that exhibit physical damage, shall be examined for damage. Consumables that show signs of damage or deterioration shall be disposed of to the satisfaction of the Company. All manual 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. Wire spools shall be stored in cabinets with the supplier's wrapping in place and shall remain clearly identifiable up to the point of usage. Unidentifiable wire shall not be used. Flux shall be handled and stored in accordance with the flux manufacturer's recommendations. The Contractor shall furnish the Company with datasheets for the flux prior to its arrival at site. Flux shall remain identifiable and traceable. Recycling shall not be permitted. Wherever available, basic coated electrodes should be supplied in sealed vacuum packs having a guaranteed hydrogen content. Electrodes not supplied in such vacuum packs shall be removed from the containers and baked in ovens in accordance with the manufacturer's instructions. The electrodes shall be transferred to holding ovens set at 150°C after baking, from where they shall be issued to heated quivers maintained at a minimum temperature of

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70°C. Duplex stainless steel electrodes shall not be stored in the same heated cabinets as electrodes of other materials. The maximum stacking height shall be four layers. The baking ovens and the holding ovens shall have automatic heat controls and a temperature read-out display. A ‘map’ or other acceptable method shall be employed so as to identify the contents and their location in the baking and holding ovens. Oven internal storage arrangements shall not allow intermixing of different electrodes (manufacturers and/or sizes). Consumable control shall be such that any basic coated electrodes shall be used within four hours of issue to a quiver. Where this is not possible due to operational reasons, vacuum seal packed electrodes shall be used, (for which the requirement for issue into a heated quiver shall still apply). Those electrodes not used within four hours shall be returned to the baking oven. Electrodes shall be baked a maximum of two times, i.e. one initial bake and one re-bake. The Contractor shall have a system for identification of re-baked electrodes. 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. Test welding or production welding shall not commence until the consumable handling procedure has been approved by the Company Welding TA - 2.

328.3.1.2

Shielding Gases

The shielding and purge gas shall be certified as complying with ISO 14175, AWS 5.32 or equivalent. Hydrogen shall not be added. The purity or component concentrations of the gas shall be as specified on the WPS and shall be the same for procedure qualification and production welding. Gases in containers that are unidentifiable shall not be used.

328.3.2 Weld Backing Material Delete existing section and replace as follows: Backing rings shall not be used.

328.3.3 Consumable Inserts Delete existing section and replace as follows: Consumable inserts shall not be used.

328.4

Preparation for Welding

328.4.1

Cleaning Delete existing section and replace as follows: Fusion faces and the surrounding surfaces within a minimum of 25 mm of the joint shall be free from heavy scale, moisture, oil, paint, or any other substance which may have a deleterious effect on the weld quality or progress. Before welding, the end preparation shall be degreased with a non-chlorinated solvent such as acetone.

328.4.2 End Preparation (a) General Delete existing clause (1) and replace as follows:

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(1) Bevels shall normally be machined or prepared by grinding. Preparation of weld edges by plasma cutting is permissible provided a mechanically guided torch is used. Prepared edges shall meet the cleanliness requirements of clause 328.4.1 of this specification. Equipment/consumables used for grinding and cleaning of edge preparations shall be dedicated for stainless steel work and identified by colour coding or other suitable means. Wire brushes shall be of stainless steel. Add the following new clauses (3) to (5): (3) The cut surface shall be ground to a smooth, bright uniform finish by removing approximately 0.5 mm of metal. After grinding, the weld edges and surrounding material shall be cleaned and visually examined to ensure freedom from cracks, notches or other defects which may affect weld quality. Any bevelled edge that has been damaged shall be restored by machining or grinding within the tolerances required by the welding procedure to be applied. Restoration involving welding shall not be permitted. (4) All preparations in pipe of 273 mm OD and above and/or wall thickness of 12.7 mm and above and all cut-backs made to rectify defective end preparation, irrespective of pipe size, shall be inspected as follows: •

• •

The pipe shall be ultrasonically examined for laminations over a zone of 50 mm back from the new bevel edge. The acceptance criteria shall be that the maximum dimension of the minor axis of the lamination shall not exceed 6.3 mm and the maximum product of the major and minor axes shall not exceed 50 mm2. The new bevel shall be liquid penetrant examined and shall be free from relevant linear indications. All examinations shall be in accordance with Company approved procedures.

(5) Prior to a cut-out for a branch connection, a zone 50 mm wide around the outside diameter of the proposed hole shall be utrasonically checked for laminations. The completed bevel shall be liquid penetrant examined. The procedures and acceptance criteria shall be those specified for cut-backs in the preceding paragraph. (b) Circumferential welds Delete existing clause (4) and replace as follows: (4) The deposition of weld metal to rectify internal misalignment shall not be permitted. 328.4.3 Alignment (a) Circumferential welds Add the following to clau se (1): Misalignment is permitted to a maximum of 1 mm provided it is distributed equally around the circumference. If the misalignment exceeds the above value, provided it is caused by dimensional variations within the specified tolerance or the use of two piping components of different nominal thickness and the same out side diameter, trimming at the internal diameter of the thicker member to a taper of 1:4 may be carried out. Wherever possible, such rectification should be carried out by machining in a shop rather than by grinding in the field. Add the following new clause, (3):

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(3) Line-up clamps shall be employed where possible. These shall have stainless steel inserts or shall be clad with a suitable material to prevent contact between the duplex stainless steel pipe and carbon steel. Stainless steel spacing tools shall be used in conjunction with the line-up clamp to ensure proper joint spacing. Root bead segments used with external line-up clamps shall be cleaned, feathered at each end, and visually inspected prior to completion of the root pass. Add the following new sub-section (e): (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 wall thickness or 50 mm whichever is greater. And both joints shall be subjected to RT and PT checks. When circumferential welds are to be made in pipe of welded manufacture, the longitudinal welds shall be so positioned that: • •

the weld is at the upper segment of 120° of the pipe line any two adjacent longitudinal welds shall be at least 45° apart.

328.5

Welding Requirements

328.5.1

General The material certificates shall be verified and approved by the contractor Quality Assurance Engineer and made available for review to the Company before the commencement of welding / fabrication. (a) WPS Add the following: All welding shall be in accordance with the ‘Approved for Fabrication’ WPS. (b) Weld identification Delete the last sentence and replace as follows: The Contractor shall maintain records of the weld number and the welder identification for each weld for inclusion in the document package. The production records shall also include the results of monitoring and verification of the welding parameters (volts, amps, travel speed and heat input) representing one pass per WPS, per welder, per day (excluding the capping runs) unless agreed otherwise with Company Welding TA-2 authority. A calibrated portable arc monitor shall be used to record welding parameters. (c) Tack welding Delete existing sub-section and replace as follows: Root tack welding shall not be permitted. Where tack welding is necessary, only bridge or bar tacks may be used. These shall be welded using the electrodes and parameters shown in the approved WPS for the fill passes. Welding shall not encroach on the root area. The bridge or bar material shall match the composition of the parent material. The tack welds shall be removed by grinding as welding progresses around the joint. (d) Weld Finishing

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Delete existing sub-section and replace as follows: 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 the cleaning and dressing operations specified in the WPS. Welds shall not be peened. When fabrication is completed, all surfaces adjacent to the welds shall be cleaned of spatter, burrs, and other imperfections that could interfere with radiographic or ultrasonic inspection. (e) Weather protection Delete existing sub-section and replace as follows: Work shall not be performed when the weather and/or degree of protection does not permit satisfactory workmanship. For site welding, shelters giving adequate protection at all times to the weld area from wind, rain and moisture shall be provided. In windy conditions the pipe ends shall be sealed to prevent through draughts Weld surfaces shall be thoroughly cleaned and dried before welding. Moisture shall be removed by means of blowers, or in exceptional cases a torch may be used in accordance with Section 330.1.1 of this specification. Add new sub-sections, (g) to (k): (g) Application of welding processes (1) Gas Tungsten Arc Welding (GTAW) Manual or automatic GTAW with filler metal addition shall be used for the root and second pass of all single sided butt welds. These processes may also be used for filling and capping passes. Automatic GTAW may be used in uphill and downhill progression. The manual GTAW process shall be restricted to uphill progression. U-groove preparation without root gap should be used for automatic welding. The tungsten electrode shall be AWS class EWTh-2 or EWCe-2. The GTAW power source shall have a high frequency starting circuit, slope-out control and gas delay facility as a minimum. Argon, Helium or Argon/Helium mixtures of at least 99.99% purity shall be used as shielding and backing gas. The use of argon containing an addition of up to 2% nitrogen is also permissible. Hydrogen additions are not permitted. Flushing with backing gas shall be carried out before welding. The oxygen content of the exit gas shall be monitored using suitable oxygen measuring equipment and welding shall not commence until a level of 0.2% or less is attained. Monitoring shall be continued during welding to ensure that this limit is not exceeded. Unless otherwise approved, gas back purge shall be maintained during the welding of all full penetration butt joints until a minimum of 6 mm. thickness of weld metal has been deposited. Continuation of back purging for further layers may be necessary, subject to the root weld inner surface meeting the specified visual acceptance criteria, as determined in procedure qualification. The same criteria shall be applied to confirm the acceptable maximum depth of partial penetration repair welds. (2) Submerged Arc Welding (SAW)

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SAW shall be used only for filling and capping in the flat position with the pipe rotated. Wire and flux shall be from the same manufacturer. (3) Shielded Metal Arc Welding (SMAW) The SMAW process shall be used only for filling and capping and only in the positions recommended by the consumable manufacturer. Welding shall not be performed in the downhill direction. (4) Other welding processes Welding shall normally be restricted to the processes listed in (1) to (3) above. Proposals to use other processes may be submitted to the Company Welding TA-2 for consideration in exceptional cases. (h) Arc strikes Arc strikes shall be ground out to a smooth profile. The ground area shall be examined by liquid penetrant examination and thickness checked. The area shall be free from cracks. Where the thickness is below the specified minimum that 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 an arc strike. Connections of current return cables shall be made directly to the work using clamps having stainless steel contact surfaces. (i) Inter-run cleaning Each run of weld metal shall be cleaned before a further run is deposited. Visible defects such as cracks, cavities, and other deposition faults shall be removed by grinding prior to deposition of further weld metal. (j) Temporary attachments Temporary attachments shall not be used. (k) Transition joints between dissimilar metals The Contractor shall consult with the Company and agree the WPS and qualification requirements.

328.5.2 Fillet and Socket Welds From 1st sentence, delete”(including socket welds)”. Add to sub-section (a), the following:: Socket welding shall not be permitted. Delete existing sub-section (b) and replace as follows (b) Where the use of slip-on flanges is agreed by the Company, attachment shall be by continuous double fillet welds. Add following new sub-section:

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(c) A specific WPS shall be prepared for each fillet weld attachment detail. Subject to review and acceptance by the Company Welding TA-2, qualification of these details may be supported by appropriate butt weld qualifications. Otherwise separate qualification in accordance with ASME IX and this specification shall be required.

328.5.4 Welded Branch Connections Add following new sub-section: (i) A specific WPS s hall be prepared for each type of branch weld detail. Separate qualification of branch welds shall be carried out in accordance with ASME B31.3 and this specification.

328.6

Weld Repair Delete entire sect ion and replace as follows:

328.6.1 General All repairs shall be executed by welders qualified in accordance with ASME B31.3 and this specification. The Contractor shall maintain records of repair work. Repair welding procedures shall be prepared and qualified for each type of repair to be performed in accordance with Section 328.2 of this specification. A separate WPS shall be produced for repair welding and shall be approved by the Company Welding TA-2. The WPS shall be qualified using simulated repairs to an appropriate test weld, except that repairs to fillet welds may be qualified by a suitable butt weld repair PQR. In addition to the items required by this specification, the WPS shall show the following: • •

The method of excavation The NDE technique employed to ensure removal of defects

Cracks shall not be repaired. When cracking is observed in the completed weld, the weld shall be cut out entirely. For partial penetration repairs, the total length of excavation 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. Each type of repair shall be separately qualified, including full penetration, partial penetration and cap welds. Excavation shall be by machining or grinding. After excavation, visual and liquid penetrant inspection shall be performed to confirm defect removal. At the ends and the sides of the excavation there shall be a gradual taper from the base of the excavation to the surface of the weld metal. The profile shall be such that adequate access for welding is achieved. Undersize welds shall be rectified by the deposition of additional weld metal, using the same procedures as for the original weld. Surfaces shall be thoroughly cleaned before depositing further weld metal. Back welding to repair a root mismatch (Hi-Lo) is only permissible if covered by a PQR. After completion of repair welding, the full extent of the repair shall be inspected by the method prescribed for the original weld to a length extending 50 mm beyond each end of the repair. Should further unacceptable defects be found on re-inspection then the weld shall be cut out entirely.

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328.6.2


Welding of Test Repair Welds The initial butt weld shall be welded to the appropriate qualified WPS. The maximum depth of partial penetration repair welds shall the lesser of 0.5t or t-6 mm. Where the execution of single run repairs has been agreed, separate qualification shall be made. Generally, test repair weld excavations should be centred at the fusion line so as to include weld metal and parent material. The location shall be shown on the WPS and agreed by the Company. Each repair shall be of sufficient length to provide the specified number of specimens for destructive testing.

328.6.3

Testing of Repair Welds Non-destructive testing of the repair test weld shall be performed as specified for the original weld. Provided the repair weld procedure is representative of the original weld qualification, the following destructive tests shall be performed on butt weld repairs, (cap repairs should be tested as fillet welds). Otherwise, full procedure qualification tests shall apply. Destructive testing shall be in accordance with the methods and acceptance criteria of Section 328.2.6: -

1 transverse tensile bend test 1 macroexamination and hardness test ferrite measurements, which shall include measurements made in the new HAZ formed in the original weld. - Charpy testing which, where appropriate, shall include samples notched in the new HAZ formed in the original weld. - corrosion testing, to include the junction of new and original weld metal

330

Preheating

330.1

General

330.1.1

Requirements and Recommendations Delete existing section and replace as follows: Preheat will not normally be required by the WPS. If welding is likely to be performed below 15°C or condensation of moisture on the weld area is possible, a minimum preheat of 50°C shall be applied to a bandwidth of at least 75mm either side of the joint. A limited preheat may also be applied in highly constrained conditions provided that this does not contravene the essential variables of the qualified WPS, (see 328.2.1.3(p)). Acceptable methods of pre-heating are electrical resistance heaters or oxy-propane torches fitted with rosebud pattern nozzles. Welding or cutting torches shall not be used. The maximum interpass temperature shall be 150oC, unless a lower value is specified on the approved WPS. Temperature measurement shall be by thermocouple, thermomelt crayon, contact pyrometer or a combination of these. Thermomelt crayons shall not be applied within the bevel area.

330.1.4

Preheat Zone Delete existing section and replace as follows: The heated area shall extend for a minimum of 75mm either side of the joint and shall be maintained over the full length of the joint until the weld is completed. A period of

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equalisation shall be allowed, based on two minutes per 25mm thickness, prior to confirmation that the specified temperature has been attained.

330.2

Specific Requirements

330.2.4 Interrupted Welding Delete existing section and replace as follows: Interruption of welding should be avoided. Where interruption is unavoidable, a minimum of three passes or one third of the joint thickness, whichever is greater, shall have been deposited.

331

Heat Treatment Delete existing section and replace as follows: Post weld heat treatment will be specified only in exceptional circumstances. Individual requirements and procedures shall be agreed with the Company as necessary.

332

Bending and Forming Delete existing section entirely and replace as follows:

332.1

General Field bending of duplex stainless steel pipework shall not be permitted. Maximum use shall be made of factory produced components. Where shop fabrication of bends or any other shop forming operations becomes necessary, this shall be restricted to cold working techniques. Contact faces of forming equipment shall be of stainless steel or lined with suitable material to prevent contamination of the work by carbon steel. Detailed fabrication and heat treatment procedures shall be approved by the Company prior to commencement of work.

333

Brazing and Soldering Delete the existing section entirely. Brazing and soldering processes are outside the scope of this specification.

Add the following new section:

336

Handling and Storage

336.1

General All necessary precautions shall be taken throughout fabrication to minimise contamination of duplex stainless steel materials resulting from direct contact with carbon steels, exposure to ferrous dust, swarf or other debris and from residual deposits on or near fusion faces during welding. Specific requirements to prevent contamination during edge preparation, joint alignment or site fabrication, for cleaning fusion faces and welds beads and for preventing oxidation during welding, are included in Sections 328.4, 328.5.1 and 332.1 of this specification. General precautions to be applied during the handling and storage of duplex stainless steels are outlined in clauses 336.2 - 3, following.

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Surface oxidation or metallic contamination that does not respond to washing or degreasing treatments shall be removed using power tools or by a pickling treatment. Pickling procedures shall be subject to prior approved by the Company. The Contractor shall ensure the safe use and disposal of chemical solutions and the thorough cleaning and drying of pipework. Washing shall be performed with potable water.

336.2

Storage (a) Components stored in an open site or within a fabrication workshop shall be protected from environmental contamination. (b) Duplex stainless steels shall be clearly identified and segregated from other stored materials.

336.3

Pipe Handling (a) Supports, rollers and other pipe handling equipment shall be of compatible material or shall be suitably lined to prevent damage or contamination of the duplex pipework. (b) Slings and supports for lifting duplex stainless steel pipe and assem blies shall be of Nylon or similar compatible material. (c) Pipe handling by means of hooks in pipe ends shall not be permitted.

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Chapter VI Inspection, Examination and Testing 341

Examination

341.2

Responsibility for Examination Add the following new sub-sections (d) and (e): (d) The Contractor shall supply all labour, materials, and equipment necessary to perform the required examinations. (e) The Company shall have the final disposition on any weld. Those welds not accepted by the Company shall be rectified in accordance with ASME B31.3 and this specification.

341.3

Examination Requirements

341.3.1 General Insert the following in front of the first paragraph: Before commencing production, the Contractor shall examine free-issue materials for damage and compliance with the relevant materials specification. This examination shall include a review of the materials certificates. Items supplied without materials certificates shall not be used. All damage and discrepancies shall be reported immediately to the Company. After signed acceptance by the Contractor, any discovered damage shall be the responsibility of the Contractor.

341.3.2

Acceptance Criteria Delete existing section and replace as follows: The acceptance criteria shall be as stated in ASME B31.3 and this specification. Limits on imperfections shall be assessed in accordance with Table 341.3.2 with the exception that Incomplete Penetration shall not be permitted, (symbol ‘A’ to be designated for girth/mitre groove welds and branch connections).

341.4

Extent of Required Examination

341.4.1 Examination Normally Required (a) Visual Examination Delete all clauses of existing sub-section and replace as follows: Visual examination prior to welding shall be in accordance with the provisions of sections 328.4 and 341.3 of ASME B31.3 and this specification. All completed welds shall be visually examined. Wherever 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. (b) Other examination Delete all clauses of existing sub-section and replace as follows: The extent of examination for all butt welds shall be in accordance with Table 1. Ultrasonic examination may supplement radiography and shall be used to interpret

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doubtful indications in the radiographs. Fillet welds shall be subjected to visual, and liquid penetrant examination at the same frequency as radiography for butt welds per fluid service and class. Branch connection welds shall be radiographically examined where possible. Where radiography is not possible, ultrasonic examination shall be employed. Where ultrasonic examination is not possible, liquid penetrant examination shall be performed on the final weld. The Contractor shall inform the Company of cases where neither radiography nor ultrasonic examination can be performed and o btain written Company approval for liquid penetrant examination to be used alone. When random non-destructive examination is s pecified, the Contractor shall ensure that a minimum of 2% of the welds made by each welder is included in the overall percentage examined. In-process examination shall not substitute for the specified NDE.

342

Examination Personnel

342.1

Personnel Qualification and Certification Delete existing section and replace as follows: Welding examination personnel shall hold a valid qualification of one of the following listed below and should have previous experience of duplex stainless steel welding or have received a period of specialised training satisfactory to the Company welding TA-2. Acceptable qualifications for welding examiners are as follows: • • •

CSWIP 3.1 with 10 years experience AWS CWI with 10 years experience Other qualification agreed by the Com pany as equivalent to the above.

Non-destructive examination personnel shall be qualified and certificated for the method of NDE to be carried out in accordance with ISO 9712. The roles and responsibilities of NDE personnel shall be as defined in the levels of competence in ISO 9712. Personnel certified to ASNT Level II in accordance with ASNT-TC-1A by examination are acceptable provided that the certifying Level III NDE Engineer has been approved by the Company. The Company approved Level III NDE Engineer (full time employee of NDE Company) shall continuously (monthly) monitor the performance of NDE Personnel certified to ASNT Level II and shall take corrective measures whenever the performance of ASNT Level II technicians is not satisfactory. If, in the opinion of the Company, welding examination or non-destructive examination personnel fail to perform to a satisfactory standard they shall be disqualified from the works until such time that it can be demonstrated by the Contractor that they have achieved a satisfactory standard by undertaking, at the Contractor's expense, a test by a third party agency approved by the Company.

343

Examination Procedur es Delete existing section and replace as follows: Written NDE procedures covering each type of specified examination shall be prepared by the Contractor and submitted for Company approval (by an Inspection TA-2) a minimum of

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two weeks prior to test or production welding as applicable. The procedures shall be project specific and shall show the project name and contract number. Company approval shall be based on qualification tests, which may be conducted as part of the Welding Procedure Qualification testing. The procedures shall incorporate the requirements of SP-1176.

344

Types of Examination

344.2

Visual Examination

344.2.2

Method Delete exist ing section and replace as follows: Visual examination shall be performed in accordance with a documented procedure complying with Article 9 of ASME BPV Code Section V. The examiner shall maintain and sign records of in-process examination. The acceptance criteria shall be as stated in Chapter VI of ASME B31.3 and this specification. The weld shall be at ambient temperature prior to examination.

344.3

Magnetic Particle Examination Delete this section.

344.4

Liquid Penetrant Examination Delete existing section and replace as follow s: Liquid penetrant examination shall be performed in accordance with a documented procedure complying with Article 6 of ASME BPV Code Section V and incorporating the requirements of SP-1176. The acceptance criteria shall be as stated in Chapter VI of ASME B31.3 and this specification. The technician and the Contractor's Welding Co-ordinator shall sign and endorse the report form before presenting it to the Company. When approved by the Company, the Company representative shall sign and endorse the report form. PT shall be performed with the weld at ambient temperature.

344.5

Radiographic Examination

344.5.3

Method Delete exist ing section and replace as follows: Radiographic examination shall be performed in accordance with a documented procedure complying with Article 2 of ASME BPV Code Section V and incorporating the requirements of SP-1176. The primary method of radiography shall be by X-ray. Gamma radiography shall not be used for wall thicknesses less than 10mm. Where the use of X-radiography is agreed by the Company to be impracticable, a gamma source may be considered subject to meeting the specified minimum sensitivity requirements. Only Class 1 film (D4 or equivalent) shall be used for radiography performed to this specification. Sensitivity shall be 2% or better. IQIs shall be wire type, of stainless steel or equivalent.

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The Contractor shall qualify the radiographic testing procedure prior to testing production welds by producing radiographs that comply with this specification. These shall be retained for reference during production and should be suitable bo th for confirmation of radiographic quality and for assessment of questionable root profile features (weld protrusion, concavity etc.) from density measurements. Radiographic testing procedure qualification may be undertaken on test welds produced for welding procedure qualification. The acceptance criteria shall be as stated in Chapter VI of ASME B31.3 and section 341.3.2 of this specification. The technician and the Contractor's Welding Examiner shall sign and endorse the report form prior to presenting it and the radiographs to the Company. When approved by the Company, the Company representative who interpreted the radiographs shall sign and endorse the report form. Radiography shall be performed with the weld at ambient temperature.

344.6

Ultrasonic Examination Delete existing section entirely and replace as follows: Ultrasonic examination for laminations and weld discontinuities shall be performed in accordance with documented procedures complying with Article 5 of ASME BPV Code Section V and incorporating t he requirements of SP-1176. The acceptance criteria shall be as stated in Chapter VI and 344.6.2 of ASME B31.3 for welds and 328.4.2(a)(4) of this specification for laminations. The technician and the Contractor's Welding Examiner shall sign and endorse the report form before presenting it to the Company. When approved by the Company, the Company representative shall sign and endorse the report form. Ultrasonic examination shall be performed with the weld at ambient temperature. Add the following new section:

345 Testing 345.1 Required Leak Test Add the following: Before hydro-test relevant pi pe spool weld history records stating all the information as detailed in 346.1 shall be verified by the Contractor Quality Assurance Engineer and approved by the company TA-3. Clearance to proceed with testing shall be obtained from the Company TA-3 before hydro-test.

346

Records

346.1

Documentation The Contractor shall be responsible for compiling the following document packages which shall be submitted to the Company upon completion of the works: (a) Pre-production • •

•

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Copy of approved Welding Procedure Register Weld plan/map Copies of approved WPSs Copies of approved repair WPSs Copies of all supporting PQRs List of approved welders and their identification

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List of PDO welders' cards Copies of the PDO welders' cards List of approved NDE operators Copies of NDE operator qualification certificates List of company approved deviations to ASME B31.3 and this specification Copies of Company approved deviations to ASME B31.3 and this specification List of consumable batch certificates Copies of consumable batch certificates List of materials certificates Copies of materials certificates List of test equipment Copies of calibration certificates

• • • • • • • • •

(b) Post-production • • • • •

• • • • •

Certificate of Compliance List of as built drawings As built drawings showing unique weld numbers List of weld history sheets, weld map Copies of weld history sheets which shall show for each weld; - Weld number - Isometric and line number - Material specifications and identification - The WPS employed - Welders' identity symbols - Date welded - Visual inspection disposition - NDE reports where ap plicable (to be attached to weld history sheet) - Type of repair, if applicable, and WPS - NDE reports for repairs (to be attached to weld history sheet) - PWHT if applicable (chart to be attached to weld history sheet) - Batch number of consumables employed Radiographs - indexed and stored in a fireproof container List of site test records Copies of site test records List of non-conformances/corrective actions issued during external or internal audits. Copies of non-conformances/corrective actions issued during external or internal audits.

Add the following new section:

347

Certificate of Conformity On satisfactory completion of the piping work, the Contractor (or Manufacturer) shall issue a declaration of compliance with this specification. The format of “Declaration of Compliance” is shown in appendix E. The “Declaration of Compliance” shall be signed by the Contractor‘s QA/QC In-charge who is approved by the Company for the contract.

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Table 1 Extent of Non-Destructive Testing for Welds

Fluid Service

Category M, Liquid Gas, Hydrogen Service (>7 bar) All other services

December 2004

ANSI Class

Type of Examination

All

Visual 100%

RT 100%

PT 100%

150 - 300 ≥ 600

100% 100%

100% 100%

10% 100%

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SP-1096

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Figure 1

Hardness Indent Locations

1.5 +- 0.5 mm X

X

XXX

X

X

X

XXX

X

X

0.5t X X

X X

XXX

X

X

X

XXX

XXX X

X

X XXX

X

X

X

X

1.5+- 0.5 mm

Hardness indentations in the HAZ spaced at 0.5m m One indentation of every set of 3 shall be as close to the fusion line as possible but shall not intersect it

1.5 +- 0.5 mm

0.5 X LEG LENGTH

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Figure 2

Version 2.0

Orientation and Location of Charpy Impact Specimens

t _ < 20mm

Notch t

2mm

Weld metal specimen

C/L Specimen axis t _ < 20mm

Notch 2mm

FL

FL + 2

Heat affected zone specimens

C/L 2mm t > 20mm

2mm Weld metal specimens

C/L

FL

FL + 2

2mm

t > 20mm

FL

FL + 2

2mm

Heat affected zone specimens

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Appendix C References In this specification, reference is made to the following publications: Note:

Unless specifically designated by date, the latest edition of each publication shall be used together with any amendments.

PDO Standards Technical Authorities System

ERD-00-02

Guidelines for the Approval of Contractors for the Fabrication of Duplex Stainless Steel

GU-225

Guideline for Granting Technical Authority System

GU-272

Quality Assurance Specification for Engineering Works

SP-1171

Methods for Non-Destructive Examination

SP-1176

Shell Group Standards Oxidation of Stainless Steel Weldments

DEP 30.10.60.31-Gen

Welded and seamless duplex and super duplex stainless steel line pipe (Amendments/supplements to API Spec. 5LC)

DEP 31.40.20.34-Gen

American Standards Chemical Plant and Petroleum Refinery Piping, 2002 Editio n

ASME B31.3

Boiler and Pressure Vessel Code, Section V, Non-Destructive Examination

ASME V

Boiler and Pressure Vessel Code, Section IX, Welding And Brazing Qualifications

ASME IX

Recommended Practice for Non-Destructive Testing Personnel Qualification and Certification

ASNT SNT-TC-1A

Standard Test Methods and Definitions for Mechanical Testing of Steel Products

ASTM A370

Methods of Preparation of Metallographic Specimens

ASTM E3

Standard Test Method for Vickers Hardness of Metallic Materials

ASTM E92

Standard Test Method for Determining Volume Fraction by Systematic Manual Point Count

ASTM E562

Standard Test Methods for Pitting and Crevice Corrosion Resistance of Stainless Steels and Related Alloys b y the Use of Ferric Chloride Solution

ASTM G48

Standard Procedures for Calibrating Magnetic Instruments

AWS 4.2

Filler Metal Procurement Guidelines

AWS 5.01

Specification for Welding Shielding Gases

AWS 5.32

Sulphide Stress Cracking Resistant Metallic Materials for Oilfield Equipment

NACE MR0175

International Standards

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Quality requirements for welding - Fusion welding of metallic materials - Part 2: Comprehensive quality requirements

ISO 3834-2 (Note 2)

Quality systems - Model for quality assurance in design, development, production, installation and servicing.

ISO 9001:2000

Non-destructive testing - Qualification and certification of personnel

ISO 9712

Welding consumables - Shielding gases for arc welding and cutting

ISO 14175

Welding Co-ordination - Tasks and Responsibilities

ISO 14731 (Note 1)

Note 1 Also published as EN 719 Note 2 Also published as EN 729

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Appendix D Determination of the Volume Fraction of Ferrite in Duplex Stainless Steel by Systematic Point Count 1.

Scope This Appendix is taken from Appendix 2 of DEP 31.40.20.34-Gen and specifies the requirements for estimating the volume fraction of delta ferrite in duplex stainless steel by systematic point counting on transverse metallographic sections. The procedure is a specific interpretation of ASTM E562, which should be referenced for additional background and definition of detail as noted.

2.

Basis of Method The method involves the superimposition of a test grid over an image, produced by an optical light microscope, of the appropriate microstructural area. The number of grid points falling within delta ferrite are counted and divided by the total number of grid points, to yield a point fraction which represents an estimate of the volume fraction of delta ferrite present within the field of view. The average point fraction taken over a number of appropriately selected fields gives an estimate of the volume fraction within the region sampled.

3.

4.

Terminology i.

Point count - the number of grid points which lie within areas of a specific phase (in this case delta ferrite).

ii.

Point fraction (P p) - the point count divided by the total number of points in the test grid.

iii.

Volume fraction (Vv) - the volume of a specific phase per unit volume, expressed as a fraction.

Test Piece Preparation Planar sections shall be taken through the parent material or the weldment, as relevant. Sections shall be perpendicular to the material surface and transverse to the welding direction, when relevant, from the locations specified in Part II - 5.1 of this DEP. Each weld sample shall section the whole of the weldment and HAZ and an area of parent material on either side of the weld. Preparation of the test pieces shall be in accordance with standard metallographic techniques, such as described in ASTM E3. It is recommended that the last grinding stage should be with 600 grit, or finer, abrasive and the final polish should be with 1µm, or finer, abrasive, e.g. diamond paste. The test piece shall be etched electrolytically in 40% KOH solution, i.e. 400 g KOH in 1000 ml of solution made with distilled water. Etching shall be carried out in a container of sufficient size to allow immersion of the test piece in the etch at a distance of ≤100 mm from the platinum cathode. Electrical contact between the test piece and power source may be made by means of a suitably shaped conducting probe. Acceptable contrast may be obtained at an anode/cathode voltage that generates a current density of 1 amp/cm2 for a period of 2-5 seconds, but trials may be necessary to determine the most appropriate conditions for a particular test piece. It may be noted that the contrast between the delta ferrite and austenite phases will probably vary through the weldment.

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5.

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Area Selection The areas in which measurements have been made shall be specified precisely, as should the exact measurement locations. The weld pass shall be stated, e.g. root, cap, fill - preferably with a number, as shall the area which has been measured, i.e. weld metal, HAZ or parent material. Where possible it should be indicated whether the area has been re-heated or is asdeposited. Any uncertainty shall be noted. The location of measurements shall be recorded on a sketch or photograph of th e section.

6.

Apparatus An optical light microscope which projects an image of the magnified micro-structure onto a viewing screen shall be used, preferably with graduated x and y translation controls. The magnification shall be selected such t hat the ferrite particles have an average dimension approximately one half of the grid point spacing. This should be judged visually in more than one field of view, before measurements are made. NOTE:

For many weldment microstructures, particularly in re-heated areas, a magnification in the range x 500 - x 1000 is suitable.

The test grid shall be marked on a transparent sheet which shall be superimposed on the magnified image of the microstructure. The grid shall consist of a square array o f equally spaced points, produced by the intersection of fine parallel lines (maximum width 0.3 mm), and shall have 16 or 25 points. It is recommended that the spacing of the points should be 10 mm along both directions parallel to the edges of the square grid, e.g. as in Figure. D2.1. At a magnification of x 1000 this corresponds to a point spacing on the actual microstructure of 10 µm.

7.

Procedure Superimpose the test grid on the magnified image of the microstructure in the chosen area of the parent material or weldment. Count the number of points which lie within the delta ferrite phase; any points which cannot be assigned positively to either phase shall be counted as one half. Delta ferrite is the phase which is stained dark by the etch, although its colour may vary significantly throughout the weldment. The austenite phase remains light coloured in all areas after etching. The test piece shall then be moved by a small amount in x and/or y so that another field is chosen. A second point count shall b e performed in the new field, provided that this field of view still falls within the specified region of the parent material or weldment. If the field of view falls outside the area of interest the specimen shall be moved back, without rotating, to an appropriate position within the specified area. Where possible the test piece should be moved without looking at the micro-structure in order to avoid bias in the choice of fields. It is recommended that the use of overlapping fields be avoided. This process shall be continued until a minimum of 400 points have been counted. When measurements are being made within the coarse grained HAZ, the operator shall first assess whether the test grid can be superimposed over an area which is entirely within the coarse grained HAZ. This can be done simply by attempting to fit the grid within a single coarse grain. If the grid size is less than the grain size, th en the technique described above shall be used. If the whole grid is to o large, a smaller area of the grid shall be used, by ignoring one or more whole rows of grid points. The area chosen may be either square or rectangular. If a rectangular grid is used, the specimen shall be rotated so that the lon g axis of the rectangle is kept parallel to the fusion boundary. Measurements in the coarse grained HAZ shall be made within 0.2 mm of the fusion line.

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The volume fraction, as defined by ASTM E 562, of delta ferrite shall be estimated by taking an average of the point fractions counted in each of the n fields as follows:

1

VV = Pp =

n

∑ Pp (i)

(equation 1)

where (i) is the field number. The 95% confidence interval (CI), as defined by ASTM E 562, shall be calculated as follows:

95%CI =

2.0s (equation 2)

n−1

where s = (

1

(equation 3)

2 0 .5

∑ [Pp (i)−Pp ] )

n −1

The accuracy of the technique shall comply with the allowable errors specified in Table D2.1 where the error is as defined in ASTM E 562.

8.

Reporting The following details shall be included in the point counting report: i. ii. iii. iv. v. vi. vii.

viii. ix. x. xi. xii. xiii. xiv.

The number of sections taken from the weld. The locations of sections taken along the weld. The polishing procedure and etching conditions. The magnification used. The number of points and shape of the grid. Whether the fields were chosen randomly or at regular intervals. If regular intervals were employed, report the spacings used. The location of the areas in which measurements were made, preferably on sketch or photograph and in words, specifying parent metal or the weld pass, the region of the weld pass (i.e. weld metal or HAZ) and, where practical, whether the area was reheated or not. Any uncertainty should be indicated. A list of the point fractions of delta ferrite in each field. An estimate of the volume fraction of delta ferrite, calculated as the average of the point fractions. The calculated value of the 95% CI. Stage of manufacture, i.e. procedure qualification, production test, etc. Location of sample and heat number. Statement of conformance with specified ferrite content. Signature of operator responsible for ferrite determination.

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Figure D2.1

Table D2.1

Two grid types suitable for systematic manual point counting of delta ferrite in duplex stainless steel

+

+

+

+

+











+

+

+

+

+











+

+

+

+

+











+

+

+

+

+











+

+

+

+

+











Allowable error in ferrite/austenite determination Volume %

Error

45-50

± 10%

40-45

± 11%

35-40

± 12%

0-35

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± 14%

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Appendix E Certificate of Compliance DECLARATION/CERTIFICATE OF COMPLIANCE FOR PIPING FABRICATION AND INSTALLATION

Description of piping

Identification no./Drawing No. Installed by: For: Design conditions: Design temperature: Medium contained: Designed by: We hereby declare that above piping work has been fabricated, installed, examined and tested in accordance with this SP-1096

Company:

Signature (Name, position, date) PROJECT QA/QC IN-CHARGE

Specimen of declaration/certificate of compliance for piping work fabrication and i nstallation

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Welding of Duplex Stainless Steel Pipelines

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