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{{Adams
{{Adams
| number = ML13211A485
| number = ML003739986
| issue date = 10/03/2013
| issue date = 04/30/1978
| title = Control of Ferrite Content in Stainless Steel Weld Metal
| title = Control of Ferrite Content in Statinless Steel Weld Metal
| author name =  
| author name =  
| author affiliation = NRC/RES
| author affiliation = NRC/RES
Line 9: Line 9:
| docket =  
| docket =  
| license number =  
| license number =  
| contact person = Karagiannis H
| contact person =  
| case reference number = DG-1279
| document report number = RG-1.031, Rev 3
| document report number = RG-1.031, Rev. 4
| package number = ML13211A479
| document type = Regulatory Guide
| document type = Regulatory Guide
| page count = 8
| page count = 5
| revision = 0
}}
}}
{{#Wiki_filter:U.S. NUCLEAR REGULATORY COMMISSION October 2013OFFICE OF NUCLEAR REGULATORY RESEARCH Revision 4REGULATORY GUIDE Technical Lead Michael Benson Written suggestions regarding this guide or development of new guides may be submitted through the NRC's public Web site under the Regulatory Guides document collection of the NRC Library at http://www.nrc.gov/reading-rm/doc-collections/reg-guides/contactus.htm Electronic copies of this regulatory guide, previous versions of this guide, and other recently issued guides are available through the NRC's public Web site under the Regulatory Guides document collection of the NRC Library at http://www.nrc.gov/reading-rm/doc-collections/. The regulatory guide is also available through the NRC's Agencywide Documents Access and Management System (ADAMS) at http://www.nrc.gov/reading-rm/adams.html, under ADAMS Accession No. ML13211A48 The regulatory analysis may be found in ADAMS under Accession No. ML13211A490 and the staff responses to the public comments on DG-1279 may be found under ADAMS Accession No. ML13211A48 REGULATORY GUIDE 1.31 (Draft was issued as DG-1279, dated October 2012) CONTROL OF FERRITE CONTENT IN STAINLESS STEEL WELD METAL INTRODUCTION
{{#Wiki_filter:Revision        3 April 1978 U.S. NUCLEAR REGULATORY COMMISSION
                                  REGULATORY GUIDE
                                    OFFICE OF STANDARDS DEVELOPMENT
                                                                      REGULATORY GUIDE 1.31 CONTROL OF FERRITE CONTENT IN
                                                              STAINLESS STEEL WELD METAL
                                                                                            presence of microfissures. Further investigations re


==Purpose==
==A. INTRODUCTION==
This guide describes a method that the staff of the U.S. Nuclear Regulatory Commission (NRC) considers acceptable for controlling ferrite content in stainless steel weld meta Applicable Rules and Regulations Title 10 of the Code of Federal Regulations, Part 50, "Domestic Licensing of Production and Utilization Facilities" (10 CFR Part 50) (Ref. 1), Appendix A, "General Design Criteria for Nuclear Power Plants," General Design Criterion (GDC) 1, "Quality Standards and Records," requires that components important to safety be designed, fabricated, erected, and tested to quality standards commensurate with the importance of the safety function to be performe GDC 14, "Reactor Coolant Pressure Boundary," requires that the reactor coolant pressure boundary be designed, fabricated, erected, and tested so that it has an extremely low probability of abnormal leakage, rapidly propagating failure, or gross ruptur Appendix B, "Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants," to 10 CFR Part 50 requires that a quality assurance program be applied to the design, construction, operation, and testing of structures, systems, and component Appendix B also requires that measures be established to ensure that special processes, including welding, are controlled and accomplished by qualified personnel using qualified procedures and that proper process monitoring is performe
lated the presence of the microfissures to the low General Design Criterion 1, "Quality Standards                                         delta ferrite content of the deposited weld metal.


==Purpose==
and Records," of Appendix A, "General Design                                              Since microfissures in austenitic welds may have an Criteria for Nuclear Power Plants," to 10 CFR Part                                        adverse effect on the integrity of components, the
of Regulatory Guides The NRC issues regulatory guides to describe to the public methods that the staff considers acceptable for use in implementing specific parts of the agency's regulations, to explain techniques that the staff uses in evaluating specific problems or postulated accidents, and to provide guidance to applicant Regulatory guides are not substitutes for regulations, and compliance with them is not require Methods and solutions that differ from those set forth in regulatory guides will be deemed acceptable if they provide a basis for the findings required for the issuance or continuance of a permit or license by the Commissio Rev. 4 of RG 1.31, Page 2 Paperwork Reduction Act This regulatory guide contains information collection requirements covered by 10 CFR Part 50 that the Office of Management and Budget (OMB) approved under OMB control number 3150-001 The NRC may neither conduct nor sponsor, and a person is not required to respond to, an information collection request or requirement unless the requesting document displays a currently valid OMB control numbe DISCUSSION Reason for Revision To achieve control of ferrite content in stainless steel welds, the original version of this guide, Safety Guide 31, "Control of Stainless Steel Welding," issued August 1972 (Ref. 2), provided guidance to test production weld This guidance was retained in Revision 1 of the Safety Guide, which was issued June 1973 as Regulatory Guide 1.31, "Control of Ferrite Content in Stainless Steel Weld Metal" (Ref. 3). Revision 2 (issued May 1977) and Revision 3 (issued April 1978) to this guide were based on recommendations from an NRC/industry study grou Revision 2 of this guide replaced the guidance for testing production welds in Revision 1 with guidance for process control through testing weld test pad These changes considerably reduced the testing effort needed to control delta ferrite in weld This revision (Revision 4) references the latest consensus standard It supplements the American Society of Mechanical Engineers (ASME) Code requirements to ensure control of delta ferrite in welds in austenitic stainless steel core support structures, reactor internals, and Class 1, 2, and 3 component Also, the Appendix of the previous version has been removed and incorporated into the relevant specifications that are referenced in this guid Background Inspection of some welds in austenitic stainless steel components of nuclear reactors has revealed the presence of microfissure Further investigations related the presence of the microfissures to the low delta ferrite content of the deposited weld meta Since microfissures in austenitic welds may have an adverse effect on the integrity of components, the control of weld deposits to ensure the presence of delta ferrite in these welds is advisabl Because licensees and other representatives of the nuclear industry believed that adequate control of filler metal ferrite content would consistently provide sound weld deposits with an absence of microfissures, ASME, the American National Standards Institute (ANSI), and the NRC formed a cooperative study group to investigate the problem and the alternatives that would ensure adequate control of ferrite conten The study group analyzed data from welds prepared by eight different procedure The group analyzed about 1,500 test results and made recommendations to both ASME and the NRC on how testing of production welds could be reduced without sacrificing control of the ferrite conten Welding Research Council (WRC) Bulletin Number 318 (Ref. 4) provides a summary of the work performed, round robin test results including statistical analysis of the reproducibility of ferrite number measurements, and the study group's recommendation The provisions of the ASME Boiler and Pressure Vessel Code (ASME Code), Section III (Ref. 5), incorporated by reference into the NRC regulations, require compliance with one of two alternative methods (either a chemical analysis method or a magnetic measurement method) to control delta ferrite in weld metal filler material The NRC staff does not consider the use of the chemical analysis method for every welding process adequate by itself to ensure control of delta ferrite in production weld The staff Rev. 4 of RG 1.31, Page 3 positions in this guide are intended to supplement the ASME Code requirements to ensure control of delta ferrite in welds in austenitic stainless steel core support structures, reactor internals, and Class 1, 2, and 3 component The staff concludes that ferrite content in the weld metal, as depicted by a ferrite number, should be between 5 and 2 This lower limit provides sufficient ferrite to avoid microfissuring in welds, whereas the upper limit provides a ferrite content adequate to offset dilution and reduce thermal aging effect Harmonization with International Standards The NRC has an interest in facilitating the harmonization of standards used domestically and internationall This regulatory guide endorses standards from the American Welding Society (AWS) and ASME, which publish standards that are used internationally for a wide range of materials, products, systems, and service The NRC staff reviewed guidance from the International Atomic Energy Agency (IAEA), but did not identify any standards related to this regulatory guide that provided useful information to NRC staff, applicants, or licensee Documents Discussed in Staff Regulatory Guidance This regulatory guide endorses, in part, the use of one or more codes or standards developed by external organizations, and other third party guidance document These codes, standards and third party guidance documents may contain references to other codes, standards or third party guidance documents ("secondary references"). If a secondary reference has itself been incorporated by reference into NRC regulations as a requirement, then licensees and applicants must comply with that standard as set forth in the regulatio If the secondary reference has been endorsed in a regulatory guide as an acceptable approach for meeting an NRC requirement, then the standard constitutes a method acceptable to the NRC staff for meeting that regulatory requirement as described in the specific regulatory guid If the secondary reference has neither been incorporated by reference into NRC regulations nor endorsed in a regulatory guide, then the secondary reference is neither a legally-binding requirement nor a "generic" NRC approval as an acceptable approach for meeting an NRC requiremen However, licensees and applicants may consider and use the information in the secondary reference, if appropriately justified and consistent with current regulatory practice, consistent with applicable NRC requirements such as 10 CFR 50.5 STAFF REGULATORY GUIDANCE 1. Verification of Delta Ferrite Content of Filler Materials Prior to production usage, the delta ferrite content of test weld deposits from each lot and each heat of weld filler metal procured for the welding of austenitic stainless steel core support structures, reactor internals, and Class 1, 2, and 3 components should be verified for each process to be used in productio The definition of heat and lot of material in ASME Code, Section III, NB-2420 can be use For all processes, delta ferrite verification should be performed through tests using magnetic measuring devices on undiluted weld deposit For submerged arc welding processes, the verification tests for each wire and flux combination may be made on a production weld or simulated production wel All other delta ferrite weld filler verification tests should be made on weld pads that contain undiluted layers of weld meta Rev. 4 of RG 1.31, Page 4 Delta ferrite determinations are not necessary for type 16-8-2 filler metal in ASME Code Section II filler metal specifications SFA-5.4, "Specification for Stainless Steel Electrodes for Shielded Metal Arc Welding," SFA-5.9, "Specification for Bare Stainless Steel Welding Electrodes and Rods" and SFA-5.22, "Specification for Stainless Steel Electrodes for Flux Cored Arc Welding and Stainless Steel Flux Cored Rods for Gas Tungsten Arc Welding," or for filler metal used for weld metal cladding (Ref. 6). Alternatively, delta ferrite determinations for consumable inserts, electrodes, rod, or wire filler metal used with the gas tungsten arc welding process, and deposits made with the plasma arc welding process, may be predicted from their chemical composition of the undiluted weld deposit by using a constitutional diagram in the applicable filler metal specification (e.g., WRC-1992 diagram for stainless steel weld metal in ASME Code Section III, Figure NB-2433.1.1). Use of the magnetic test method is also acceptable to the staff for determining delta ferrite content in welds fabricated with gas tungsten arc welding and plasma arc welding. 2. Ferrite Measurement The NRC staff considers the procedures for pad preparation and ferrite measurement in SFA-5.4 of Section II of the ASME Code acceptable. 3. Instrumentation The weld pad should be examined for ferrite content by using a magnetic measuring instrument that has been calibrated against a Magnegage in accordance with AWS A4.2, "Standard Procedures for Calibrating Magnetic Instruments to Measure the Delta Ferrite Content of Austenitic and Duplex Ferritic-Austenitic Stainless Steel Weld Metal" (Ref. 7). The Magnegage should have been previously calibrated in accordance with AWS A4.2 using primary standards as defined therein. 4. Acceptability of Test Results Weld pad test results showing an average ferrite number from 5 to 20 indicate that the filler metal is acceptable for the production welding of Class 1, 2, and 3 austenitic stainless steel components, reactor internals, and core support structure . Quality Assurance The applicable provisions of Appendix B to 10 CFR Part 50 should be used to verify compliance with requirements for delta ferrite of each lot and each heat of weld filler metal as described herei Rev. 4 of RG 1.31, Page 5 IMPLEMENTATION The purpose of this section is to provide information on how applicants and licensees1 may use this guide and information regarding the NRC's plans for using this regulatory guid In addition, it describes how the NRC staff complies with 10 CFR 50.109, "Backfitting," and any applicable finality provisions in 10 CFR Part 52, "Licenses, Certifications, and Approvals for Nuclear Power Plants." Use by Applicants and Licensees Applicants and licensees may voluntarily2 use the guidance in this document to demonstrate compliance with the underlying NRC regulation Methods or solutions that differ from those described in this regulatory guide may be deemed acceptable if they provide sufficient basis and information for the NRC staff to verify that the proposed alternative demonstrates compliance with the appropriate NRC regulation Current licensees may continue to use guidance the NRC found acceptable for complying with the identified regulations as long as their current licensing basis remains unchange Licensees may use the information in this regulatory guide for actions that do not require NRC review and approval, such as changes to a facility design under 10 CFR 50.59, "Changes, Tests, and Experiments." Licensees may use the information in this regulatory guide or applicable parts to resolve regulatory or inspection issue Use by NRC Staff The NRC staff does not intend or approve any imposition or backfitting of the guidance in this regulatory guid The NRC staff does not expect any existing licensee to use or commit to using the guidance in this regulatory guide, unless the licensee makes a change to its licensing basi The NRC staff does not expect or plan to request licensees to voluntarily adopt this regulatory guide to resolve a generic regulatory issu The NRC staff does not expect or plan to initiate NRC regulatory action that would require the use of this regulatory guid Examples of such unplanned NRC regulatory actions include issuance of an order requiring the use of the regulatory guide, requests for information under 10 CFR 50.54(f) as to whether a licensee intends to commit to use of this regulatory guide, generic communication, or promulgation of a rule requiring the use of this regulatory guide without further backfit consideratio During regulatory discussions on plant specific operational issues, the staff may discuss with licensees various actions consistent with staff positions in this regulatory guide, as one acceptable means of meeting the underlying NRC regulatory requiremen Such discussions would not ordinarily be considered backfitting even if prior versions of this regulatory guide are part of the licensing basis of the facilit However, unless this regulatory guide is part of the licensing basis for a facility, the staff may not represent to the licensee that the licensee's failure to comply with the positions in this regulatory guide constitutes a violatio In this section, "licensees" refers to licensees of nuclear power plants under 10 CFR Parts 50 and 52, and "applicants" refers to applicants for licenses and permits for (or relating to) nuclear power plants under 10 CFR Parts 50 and 52, and applicants for standard design approvals and standard design certifications under 10 CFR Part 5 In this section, "voluntary" and "voluntarily" mean that the licensee is seeking the action of its own accord, without the force of a legally binding requirement or an NRC representation of further licensing or enforcement actio Rev. 4 of RG 1.31, Page 6 If an existing licensee voluntarily seeks a license amendment or change and (1) the NRC staff's consideration of the request involves a regulatory issue directly relevant to this new or revised regulatory guide and (2) the specific subject matter of this regulatory guide is an essential consideration in the staff's determination of the acceptability of the licensee's request, then the staff may request that the licensee either follow the guidance in this regulatory guide or provide an equivalent alternative process that demonstrates compliance with the underlying NRC regulatory requirement This is not considered backfitting as defined in 10 CFR 50.109(a)(1) or a violation of any of the issue finality provisions in 10 CFR Part 5 Additionally, an existing applicant may be required to comply with new rules, orders, or guidance if 10 CFR 50.109(a) (3) applie If a licensee believes that the NRC is either using this regulatory guide or requesting or requiring the licensee to implement the methods or processes in this regulatory guide in a manner inconsistent with the discussion in this Implementation section, then the licensee may file a backfit appeal with the NRC in accordance with the guidance in NUREG-1409, "Backfitting Guidelines," (Ref. 8) and the NRC Management Directive 8.4, "Management of Facility-Specific Backfitting and Information Collection" (Ref. 9).
  50 requires that components- important to safety be                                       control of weld deposits to ensure the presence of designed, fabricated, erected, and tested to quality                                      delta ferrite in these welds is advisable.


Rev. 4 of RG 1.31, Page 7 REFERENCES3 1. U.S. Code of Federal Regulations (CFR) "Domestic Licensing of Production and Utilization Facilities," Part 50, Chapter 1, Title 10, "Energy" 2. Safety Guide 31, "Control of Stainless Steel Welding," U.S. Nuclear Regulatory Commission, Washington, D . Regulatory Guide 1.31, "Control of Ferrite Content in Stainless Steel Weld Metal," U.S. Nuclear Regulatory Commission, Washington, D . Welding Research Council (WRC) Bulletin Number 318, "Factors Influencing the Measurement of Ferrite Content in Austenitic Stainless Steel Weld Metal Using Magnetic Instruments," W. W. Pickering, E. S. Robitz, and D. M. Vandergriff, September 1986 (ISBN#1-58145-317-5).4 5. American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code, Section III, "Rules for Construction of Nuclear Facility Components," American Society of Mechanical Engineers (as incorporated by reference in 10 CFR 50.55a). 5 6. ASME Boiler and Pressure Vessel Code, Section II, Part C, "Specifications for Welding Rods, Electrodes, and Filler Metals," American Society of Mechanical Engineers, (as approved by the ASME in those Editions and Addenda of the ASME Boiler and Pressure Vessel Code, Section III, Subsection NCA-1140 which are incorporated by reference into 10 CFR 50.55a). 7. Welding Society (AWS) A4.2, "Standard Procedures for Calibrating Magnetic Instruments to Measure the Delta Ferrite Content of Austenitic and Duplex Ferritic-Austenitic Stainless Steel Weld Metal," AWS, (as approved by the ASME in those Editions and Addenda of the ASME Boiler and Pressure Vessel Code, Section III, which are incorporated by reference into 10 CFR 50.55a.). 6 8. NUREG 1409, "Backfitting Guidelines," U.S. Nuclear Regulatory Commission, Washington, D Publicly available NRC published documents are available electronically through the NRC Library on the NRC's public Web site at http://www.nrc.gov/reading-rm/doc-collections/ and also available through the NRC's Agencywide Documents Access and Management System (ADAMS) at http://www.nrc.gov/reading-rm/adams.html The documents can also be viewed online or printed for a fee in the NRC's Public Document Room (PDR) at 11555 Rockville Pike, Rockville, MD. For problems with ADAMS, contact the PDR staff at 301-415-4737 or (800) 397-4209; fax (301) 415-3548; or e-mail pdr.resource@nrc.go This reference is available for purchase at the Welding Research Council (WRC) website at http://www.forengineers.org/wrc/ or by contacting WRC at P.O. Box 201547, Shaker Heights, OH 4412 Copies of American Society of Mechanical Engineers (ASME) standards may be purchased from ASME, Three Park Avenue, New York, NY 10016-5990; telephone (800) 843-276 Purchase information is available through the ASME Web-based store at http://www.asme.org/Codes/Publications/. 6 Publications of the American Welding Society (AWS) may be obtained through the AWS Website at http://www.aws.org/w/a or by contacting the AWS at 8669 Doral Boulevard, Suite 130 Doral, F Rev. 4 of RG 1.31, Page 8 9. Management Directive 8.4, "Management of Facility-Specific Backfitting and Information Collection," U.S. Nuclear Regulatory Commission, Washington, DC.}}
standards commensurate with the importance of the                                              As part of achieving this control, recommendations
* safety function to be performed. Criterion 14, "Reac                                      to test production welds were made in the original tor Coolant Pressure Boundary," of Appendix A re                                          version of this guide (Safety Guide 31, "Control of quires that the reactor coolant pressure boundary be                                      Stainless Steel Welding"), and these recommenda designed, fabricated, erected, and tested so as to have                                  tions were retained in Revision 1. Because licensees an extremely low probability of abnormal leakage, of                                      and other representatives of the nuclear industry be rapidly propagating failure, and of gross rupture. Ap                                    lieved that adequate control of filler metal ferrite con
  "pendix B, "Quality Assurance Criteria for Nuclear                                       tent would consistently provide sound weld deposits Power Plants and Fuel Processing Plants," to 10 CFR                                      with an absence of microfissures, a cooperative study Part 50 requires that a quality assurance program be                                      group was formed by ASME, ANSI, and NRC to in applied to the design, construction, and operation of                                     vestigate the problem and the alternatives that would structures, systems, and components. Appendix B                                          ensure adequate control of ferrite content. The study also requires that measures be established to ensure                                      group analyzed data from welds prepared by eight that special processes, including welding, are con                                        different procedures. About 1500 test results were trolled and accomplished by qualified personnel                                            analyzed, and recommendations were made to both using qualified procedures and that proper process                                        ASME and NRC on how testing of production welds monitoring be performed.                                                                  could be reduced without sacrifice of ferrite content This guide describes a method acceptable to the                                        control. Revision 2 and this Revision 3 are based on NRC staff for implementing these requirements with                                        those recommendations. At present, the ASME
  regard to the control of welding in fabricating and                                        Code* provisions incorporated by reference into the joining safety-related austenitic stainless steel com                                      NRC regulations require compliance with one of two ponents and systems in light-water-cooled nuclear                                        alternative methods for control of delta ferrite in weld power plants. The Advisory Committee on Reactor                                          metal filler materials; either a chemical analysis Safeguards has been consulted concerning this guide                                      method or a magnetic measurement method. The and has concurred in the regulatory position.                                             NRC staff does not consider either method adequate
 
==B. DISCUSSION==
Inspection of some welds in austenitic stainless                                   
* Winter 1976 Addenda, Section III, "Nuclear Power Plant steel components of nuclear reactors has revealed the                                    Components," ASME Boiler and Pressure Vessel Code. Copies may be obtained from the American Society of Mechanical En gineers, United Engineering Center, 345 East 47th Street, New York. New York 10017.
 
* Lines indicate substantive changes from previous issue.
 
Comments should be sent to the Secretary      of the Commission, U.S. Nuclear Regu.
 
USNRC REGULATORY GUIDES                                            latory Commission. Washington. D.C.      20555. Attention Docketing and Service Regulatory Guides are issued to describe and make available to the public methods        Branch.
 
acceptable to the NRC staff of implementing specific parts of the Commission's regulations. to delineate techniques used by the staff in evaluating specific problems  The guides are issued in the following ten broad divisions or postulated accidents, or to provide guidance to applicants. Regulatory Guides                                                     
 
===6. Products===
                                                                                              1.  Power Reactors are not substitutes for regulations. and compliance with them is not require
 
====d.      ====
 
===7. Transportation===
                                                                                              2.  Research and Test Reactors Methods and solutions different from those set out in the guides will be accept.        3.  Fuelsand Materials Facilities            8.  Occupational Health able if they provide a basis for the findings requisite to the issuance or continuance  4. Environmental and Siting                9  Antitrust Review of a permit or license by the Commitsion.                                               5. Materials and Plant Protection          10.  General Comments and suggestions for improvements in these guides are encouraged at all          Requests for single copies of issued guides (which may be reproducedI or for place ment on an automatic distribution list for single copies of future guides in specific times, and guides will be revised, as appropriate, to accommodate comments and to reflect new information or experience. This guide was revised as a result of          divisions should be made in writing to the US. Nuclear Regulatory Commission.
 
Washington. D.C. 20555, Attention        Director. Division of Document Control.
 
substantive comments received from the public and additional staff review.
 
by itself to ensure controlled delta ferrite in produc                Chromium and Chromium-Nickel Steel Covered tion welds. The recommendations of this guide are                    Welding Electrodes,"* which describes a procedure intended to supplement the ASME Code requirements                    for pad preparation and ferrite measurement. The to ensure control of delta ferrite in welds in austenitic            NRC staff considers this procedure acceptable for use stainless steel core support structures and Class 1 and               with covered electrodes.
 
2 components.                                                        3. Instrumentation The recommendations for testing of production                        The weld pad should be examined for ferrite con welds in Revision 1 of this guide have been replaced                  tent by a magnetic measuring instrument which has by recommendations for process control by testing of                  been calibrated against a Magnegage in accordance weld test pads. These changes will considerably re                    with American Welding Society Specification AWS
duce the testing effort needed to control delta ferrite              A4.2-74, "Procedures for Calibrating Magnetic In in welds.                                                            struments to Measure the Delta Ferrite Content of The staff recommends that ferrite content in the                  Austenitic Stainless Steel Weld Metal."'** The Mag weld filler metal as depicted by a ferrite number (FN)                negage should have been previously calibrated in ac be between 5 and 20. This lower limit provides suffi                  cordance with AWS A4.2-74 using primary standards cient ferrite to avoid microfissuring in welds,                       as defined therein.
 
whereas the upper limit provides a ferrite content                    4. Acceptability of Test Results adequate to offset dilution.                                              Weld pad test results showing an average Ferrite Number from 5 to 20 indicate that the filler metal is
 
==C. REGULATORY POSITION==
acceptable for production welding of Class 1 and 2
1. Verification of Delta Ferrite Content of Filler                  austenitic stainless steel components and core support Materials                                                        structures.
 
Prior to production usage, the delta ferrite content                  The upper limit of 20 may be waived for (a) welds of test weld deposits from each lot and each heat of                 that do not receive postweld stress relief heat treat weld filler metal procured for the welding of austeni                ment or welds for which such postweld stress relief tic stainless steel core support structures and Class 1              treatment is conducted at temperatures less than and 2 components should be verified for each process                900'F, (b) welds that are given a solution annealing to be used in production.                                            heat treatment, and (c) welds that employ consuma ble inserts.
 
It is not necessary to make delta ferrite determina
                                                                      5. Quality Assurance tions for SFA-5.4 type 16-8-2 weld metal or for filler The applicable provisions of 10 CFR Part 50, Ap metal used for weld metal cladding. Delta ferrite de terminations for consumable inserts, electrodes, rod                pendix B, should be used in verifying compliance or wire filler metal used with the gas tungsten arc                  with requirements for delta ferrite as described herein.
 
welding process, and deposits made with the plasma arc welding process may be predicted from their chemical composition using an applicable constitu                                   
 
==D. IMPLEMENTATION==
tional diagram to demonstrate compliance. Delta fer rite verification should be made for all other proc                      The purpose of this section is to provide informa esses by tests using magnetic measuring devices on                    tion to applicants regarding the NRC staff's plans for undiluted weld deposits. For submerged arc welding                    using this regulatory guide.
 
processes, the verification tests for each wire and                      Except in those cases in which the applicant pro flux combination may be made on a production weld                    poses an acceptable alternative method for complying or simulated production weld. All other delta ferrite                with specified portions of the Commission's regula weld filler verification tests should be made on weld                tions, the method described herein will be used in the pads that contain undiluted layers of weld metal.                    evaluation of submittals in connection with construc tion permit applications docketed after October 1,
 
===2. Ferrite Measurement===
                                                                      1978.
 
Appendix A to this guide contains extracts from a If an applicant wishes to use this regulatory guide future edition of the American Welding Society's                     in developing submittals for applications docketed on AWS A5.4, "Specification for Corrosion-Resisting                      or before October 1, 1978, the pertinent portions of
 
* This specification has been recommended by the Subcommit            the application will be evaluated on the basis of this tee on Welding of Stainless Steels of the High Alloys Committee      guide.
 
of the Welding Research Council and has been approved by the American Welding Society (AWS). It is expected to be pub              **Copies may be obtained from the American Welding Society, lished as AWS A5.4-78.                                                2501 N.W. 7th Street, Miami, Florida 33125.
 
1.31-2
 
APPENDIX A
    The following is mainly extracted from a future                        A4.10.3 The welding current used for the size of edition of the American Welding Society's (AWS)                         the electrode being tested may be as specified in Fig
"Specification for Corrosion-Resisting Chromium                        ure 4 and the arc length shall be as short as practica and Chromium-Nickel Steel Covered Welding Elec                          ble. The weld bead layers may be deposited with a trodes," which the AWS plans to publish as AWS                          weave, if 'necessary, to fill the space between the A5.4-78.* This material describes a procedure for                      copper bars. The arc shall not be allowed to impinge weld pad preparation and ferrite measurement of cov                    on the copper bars. The welding direction for each ered electrode** deposits.                                              pass shall be alternated and the weld stops and starts shall be located at the ends of the weld buildup. Each EXTRACT:                                                                pass shall be cleaned prior to depositing the next A4. 10 When it is desired to measure ferrite con                    weld bead. The maximum interpass temperature shall tent, the following procedure is recommended:                            be 95'C (200°F).** Between passes, the weld pad A4.10.1 Weld pads as detailed in Figure 4 are                        may be cooled by quenching in water not sooner than prepared as prescribed in paragraphs A4.10.2                            20 seconds after the completion of each pass. The through A4.10.4.                                                        last pass shall be air-cooled to below 430'C (800'F)
    A4.10.2 The weld pad shall be built up between                      prior to quenching in water.
 
two copper bars laid parallel on the base plate by de                      A4.10.4 The completed weld pad shall be draw positing single weld bead layers, one on top of the                     filed, machined, or surface ground to provide suffi other, to a minimum height of 13 mm (1/2in.). The                        cient finished surface to make the required ferrite spacing between the copper bars for the size of the                      readings. Draw filing or its equivalent filing method electrode being tested shall be as specified in Figure                  shall be performed with a 360 mm (14 in.)** mill
4. An optional welding fixture is shown in Figure 5.                     bastard file held on both sides of the weld with the If carbon steel is used as the base plate, the weld pad                  long axis of the file perpendicular to the long axis of shall be built up to a minimum height of 16 mm (5                        the weld. The file should preferably not have been in.).                                                                    previously used on ferritic material and should be
 
* When published, copies of AWS A5.4-78 may be purchased               free from loosely adhering materials if previously from the American Welding Society, 2501 N.W. 7th Street,               used. Draw filing shall be accomplished by smooth Miami, Florida 33125.                                                  forward and backward strokes along the length of the
** Note: The U.S. customary units in this specification are            weld while applying a firm downward pressure.
 
given as equivalent values to the SI units. The standard sizes and dimensions used in the two systems are not identical and for Crossfiling shall not be permitted. The finished this reason conversion from a standard size of dimension in one        machined, ground, or filed surface shall be smooth system will not always coincide with the standard size of dimen          with all traces of weld ripple removed and shall be sion in the other. Suitable conversions encompassing standard          continuous in the length where measurements are to sizes of both can be made if appropriate tolerances are applied in      be taken. The width of the prepared surface shall not each case. The SI values (including tolerances) given here for filler metal diameter, length, and package size were selected to        be less than 3 mm (1/8in.).**
fit the product sizes which presently are U.S. standards. Toler            A4.10.5 A total of six ferrite readings shall be ances are used in some cases in this specification but not in            taken on the prepared surface along the longitudinal others. In those cases where no tolerances are given, the values        axis of the weld pad with an instrument calibrated in are those that would be obtained if the measurements were taken in SI units. In this specification, a covered electrode is defined      accordance with the procedures specified in AWS
as follows: Covered Electrode-A composite filler-metal elec              A4.2, "Standard Procedures for Calibrating Magnetic trode consisting of a core of a bare electrode or metal cored            Instruments to Measure the Delta Ferrite Content of electrode to which a covering sufficient to provide a slag layer        Austenitic Stainless Steel Weld Metal" (latest edition).
on the weld metal has been applied. The covering may contain                A4.10.6 The six readings 'obtained shall be aver materials providing such functions as shielding from the atmos phere, deoxidation, and arc stabilization and can serve as a              aged to a single value for conversion to Ferrite source of metallic additions to the weld.                                Number.
 
1.31-3
 
-  LL
                                                        Ferrite shall be measured in this area free of arc
                -H                                        starts and craters              1 Copper bar                                I
                                                                                        I
                                                                                        I
25x25x75                                                BASE PLATE
                                          1465              min                        .
          1 40  -25 min  o                                                              I
            All dimensions in millimetres, U.S. EQUIVALENTS*
                                                                    mm            in.
 
1.6          1/16
                                                                      2.0          5/64
                                                                      2.4          3/32
                                                                      3.2          1/8
                                                                      4.0          5/32
                                                                      4.8          3/16 Electrode        Welding  In drawing above                          6.4          1/4 diameter        current    (approx. mm)                            6        0.25 (mm)        (amperes)    W          L                            8         0.3
                                                                      9.5          3/8
    1.6            35-45      6        30                        10          0.4
    2.0            45-55      6        30                        13          0.5
  2.4              65-75      8         40                        15          0.6
    3.2            90-100    10        40                        18          0.7
  4.0            120-140    13        40                        25          1
  4.8            165-185    15        40                          30        1-1/4
                  240-260    18        40                        40          1-1/2
                                                                    65        2-1/2
                                                                    75        3 See Editor's Note on Page 1.31-3.
 
Fig 4 - Details of Weld Pad for Ferrite Test
                                      1.31-4
 
Copper bars 85 long of cross section as shown in A-A' below.
 
Copper bar 16 high x
  9.5 thick x 70 lon
 
====g. Copper bar same====
                                                                              -as      shown at opposite end A
I
                                                                                        Type 1 For 4.0 dia. Electrodes and smaller Note:  All dimensions are in millimetres.
 
COPPER
                                                                      16            BAR
              U.S. EQUIVALENTS*
              MM          in.
 
T      Cross Section A-A'
              4.0        5/32 This design allows increased visibility,
              4.8        3/16                    making it easier to hold a short arc length.
 
9.5        3/8
            16          5/8
            25          1                              COPPEIR                  COPPER
                                                          BAR                      BAR
            70          2-3/4                          25 square
            85          3-3/8 Type 2
    *See Editor's Note on Page 1.31-3.
 
For 4.8 & larger welding electrodes and for any pads on carbon steel base plate Fig. 5 - Optional Welding Fixture for Welding Ferrite Test Pads
                                                1.31-5}}


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Latest revision as of 10:25, 28 March 2020

Control of Ferrite Content in Statinless Steel Weld Metal
ML003739986
Person / Time
Issue date: 04/30/1978
From:
Office of Nuclear Regulatory Research
To:
References
RG-1.031, Rev 3
Download: ML003739986 (5)
v • d • e


Revision 3 April 1978 U.S. NUCLEAR REGULATORY COMMISSION

REGULATORY GUIDE

OFFICE OF STANDARDS DEVELOPMENT

REGULATORY GUIDE 1.31 CONTROL OF FERRITE CONTENT IN

STAINLESS STEEL WELD METAL

presence of microfissures. Further investigations re

A. INTRODUCTION

lated the presence of the microfissures to the low General Design Criterion 1, "Quality Standards delta ferrite content of the deposited weld metal.

and Records," of Appendix A, "General Design Since microfissures in austenitic welds may have an Criteria for Nuclear Power Plants," to 10 CFR Part adverse effect on the integrity of components, the

50 requires that components- important to safety be control of weld deposits to ensure the presence of designed, fabricated, erected, and tested to quality delta ferrite in these welds is advisable.

standards commensurate with the importance of the As part of achieving this control, recommendations

  • safety function to be performed. Criterion 14, "Reac to test production welds were made in the original tor Coolant Pressure Boundary," of Appendix A re version of this guide (Safety Guide 31, "Control of quires that the reactor coolant pressure boundary be Stainless Steel Welding"), and these recommenda designed, fabricated, erected, and tested so as to have tions were retained in Revision 1. Because licensees an extremely low probability of abnormal leakage, of and other representatives of the nuclear industry be rapidly propagating failure, and of gross rupture. Ap lieved that adequate control of filler metal ferrite con

"pendix B, "Quality Assurance Criteria for Nuclear tent would consistently provide sound weld deposits Power Plants and Fuel Processing Plants," to 10 CFR with an absence of microfissures, a cooperative study Part 50 requires that a quality assurance program be group was formed by ASME, ANSI, and NRC to in applied to the design, construction, and operation of vestigate the problem and the alternatives that would structures, systems, and components. Appendix B ensure adequate control of ferrite content. The study also requires that measures be established to ensure group analyzed data from welds prepared by eight that special processes, including welding, are con different procedures. About 1500 test results were trolled and accomplished by qualified personnel analyzed, and recommendations were made to both using qualified procedures and that proper process ASME and NRC on how testing of production welds monitoring be performed. could be reduced without sacrifice of ferrite content This guide describes a method acceptable to the control. Revision 2 and this Revision 3 are based on NRC staff for implementing these requirements with those recommendations. At present, the ASME

regard to the control of welding in fabricating and Code* provisions incorporated by reference into the joining safety-related austenitic stainless steel com NRC regulations require compliance with one of two ponents and systems in light-water-cooled nuclear alternative methods for control of delta ferrite in weld power plants. The Advisory Committee on Reactor metal filler materials; either a chemical analysis Safeguards has been consulted concerning this guide method or a magnetic measurement method. The and has concurred in the regulatory position. NRC staff does not consider either method adequate

B. DISCUSSION

Inspection of some welds in austenitic stainless

  • Winter 1976 Addenda,Section III, "Nuclear Power Plant steel components of nuclear reactors has revealed the Components," ASME Boiler and Pressure Vessel Code. Copies may be obtained from the American Society of Mechanical En gineers, United Engineering Center, 345 East 47th Street, New York. New York 10017.
  • Lines indicate substantive changes from previous issue.

Comments should be sent to the Secretary of the Commission, U.S. Nuclear Regu.

USNRC REGULATORY GUIDES latory Commission. Washington. D.C. 20555. Attention Docketing and Service Regulatory Guides are issued to describe and make available to the public methods Branch.

acceptable to the NRC staff of implementing specific parts of the Commission's regulations. to delineate techniques used by the staff in evaluating specific problems The guides are issued in the following ten broad divisions or postulated accidents, or to provide guidance to applicants. Regulatory Guides

6. Products

1. Power Reactors are not substitutes for regulations. and compliance with them is not require

d.

7. Transportation

2. Research and Test Reactors Methods and solutions different from those set out in the guides will be accept. 3. Fuelsand Materials Facilities 8. Occupational Health able if they provide a basis for the findings requisite to the issuance or continuance 4. Environmental and Siting 9 Antitrust Review of a permit or license by the Commitsion. 5. Materials and Plant Protection 10. General Comments and suggestions for improvements in these guides are encouraged at all Requests for single copies of issued guides (which may be reproducedI or for place ment on an automatic distribution list for single copies of future guides in specific times, and guides will be revised, as appropriate, to accommodate comments and to reflect new information or experience. This guide was revised as a result of divisions should be made in writing to the US. Nuclear Regulatory Commission.

Washington. D.C. 20555, Attention Director. Division of Document Control.

substantive comments received from the public and additional staff review.

by itself to ensure controlled delta ferrite in produc Chromium and Chromium-Nickel Steel Covered tion welds. The recommendations of this guide are Welding Electrodes,"* which describes a procedure intended to supplement the ASME Code requirements for pad preparation and ferrite measurement. The to ensure control of delta ferrite in welds in austenitic NRC staff considers this procedure acceptable for use stainless steel core support structures and Class 1 and with covered electrodes.

2 components. 3. Instrumentation The recommendations for testing of production The weld pad should be examined for ferrite con welds in Revision 1 of this guide have been replaced tent by a magnetic measuring instrument which has by recommendations for process control by testing of been calibrated against a Magnegage in accordance weld test pads. These changes will considerably re with American Welding Society Specification AWS

duce the testing effort needed to control delta ferrite A4.2-74, "Procedures for Calibrating Magnetic In in welds. struments to Measure the Delta Ferrite Content of The staff recommends that ferrite content in the Austenitic Stainless Steel Weld Metal."'** The Mag weld filler metal as depicted by a ferrite number (FN) negage should have been previously calibrated in ac be between 5 and 20. This lower limit provides suffi cordance with AWS A4.2-74 using primary standards cient ferrite to avoid microfissuring in welds, as defined therein.

whereas the upper limit provides a ferrite content 4. Acceptability of Test Results adequate to offset dilution. Weld pad test results showing an average Ferrite Number from 5 to 20 indicate that the filler metal is

C. REGULATORY POSITION

acceptable for production welding of Class 1 and 2

1. Verification of Delta Ferrite Content of Filler austenitic stainless steel components and core support Materials structures.

Prior to production usage, the delta ferrite content The upper limit of 20 may be waived for (a) welds of test weld deposits from each lot and each heat of that do not receive postweld stress relief heat treat weld filler metal procured for the welding of austeni ment or welds for which such postweld stress relief tic stainless steel core support structures and Class 1 treatment is conducted at temperatures less than and 2 components should be verified for each process 900'F, (b) welds that are given a solution annealing to be used in production. heat treatment, and (c) welds that employ consuma ble inserts.

It is not necessary to make delta ferrite determina

5. Quality Assurance tions for SFA-5.4 type 16-8-2 weld metal or for filler The applicable provisions of 10 CFR Part 50, Ap metal used for weld metal cladding. Delta ferrite de terminations for consumable inserts, electrodes, rod pendix B, should be used in verifying compliance or wire filler metal used with the gas tungsten arc with requirements for delta ferrite as described herein.

welding process, and deposits made with the plasma arc welding process may be predicted from their chemical composition using an applicable constitu

D. IMPLEMENTATION

tional diagram to demonstrate compliance. Delta fer rite verification should be made for all other proc The purpose of this section is to provide informa esses by tests using magnetic measuring devices on tion to applicants regarding the NRC staff's plans for undiluted weld deposits. For submerged arc welding using this regulatory guide.

processes, the verification tests for each wire and Except in those cases in which the applicant pro flux combination may be made on a production weld poses an acceptable alternative method for complying or simulated production weld. All other delta ferrite with specified portions of the Commission's regula weld filler verification tests should be made on weld tions, the method described herein will be used in the pads that contain undiluted layers of weld metal. evaluation of submittals in connection with construc tion permit applications docketed after October 1,

2. Ferrite Measurement

1978.

Appendix A to this guide contains extracts from a If an applicant wishes to use this regulatory guide future edition of the American Welding Society's in developing submittals for applications docketed on AWS A5.4, "Specification for Corrosion-Resisting or before October 1, 1978, the pertinent portions of

  • This specification has been recommended by the Subcommit the application will be evaluated on the basis of this tee on Welding of Stainless Steels of the High Alloys Committee guide.

of the Welding Research Council and has been approved by the American Welding Society (AWS). It is expected to be pub **Copies may be obtained from the American Welding Society, lished as AWS A5.4-78. 2501 N.W. 7th Street, Miami, Florida 33125.

1.31-2

APPENDIX A

The following is mainly extracted from a future A4.10.3 The welding current used for the size of edition of the American Welding Society's (AWS) the electrode being tested may be as specified in Fig

"Specification for Corrosion-Resisting Chromium ure 4 and the arc length shall be as short as practica and Chromium-Nickel Steel Covered Welding Elec ble. The weld bead layers may be deposited with a trodes," which the AWS plans to publish as AWS weave, if 'necessary, to fill the space between the A5.4-78.* This material describes a procedure for copper bars. The arc shall not be allowed to impinge weld pad preparation and ferrite measurement of cov on the copper bars. The welding direction for each ered electrode** deposits. pass shall be alternated and the weld stops and starts shall be located at the ends of the weld buildup. Each EXTRACT: pass shall be cleaned prior to depositing the next A4. 10 When it is desired to measure ferrite con weld bead. The maximum interpass temperature shall tent, the following procedure is recommended: be 95'C (200°F).** Between passes, the weld pad A4.10.1 Weld pads as detailed in Figure 4 are may be cooled by quenching in water not sooner than prepared as prescribed in paragraphs A4.10.2 20 seconds after the completion of each pass. The through A4.10.4. last pass shall be air-cooled to below 430'C (800'F)

A4.10.2 The weld pad shall be built up between prior to quenching in water.

two copper bars laid parallel on the base plate by de A4.10.4 The completed weld pad shall be draw positing single weld bead layers, one on top of the filed, machined, or surface ground to provide suffi other, to a minimum height of 13 mm (1/2in.). The cient finished surface to make the required ferrite spacing between the copper bars for the size of the readings. Draw filing or its equivalent filing method electrode being tested shall be as specified in Figure shall be performed with a 360 mm (14 in.)** mill

4. An optional welding fixture is shown in Figure 5. bastard file held on both sides of the weld with the If carbon steel is used as the base plate, the weld pad long axis of the file perpendicular to the long axis of shall be built up to a minimum height of 16 mm (5 the weld. The file should preferably not have been in.). previously used on ferritic material and should be

  • When published, copies of AWS A5.4-78 may be purchased free from loosely adhering materials if previously from the American Welding Society, 2501 N.W. 7th Street, used. Draw filing shall be accomplished by smooth Miami, Florida 33125. forward and backward strokes along the length of the
    • Note: The U.S. customary units in this specification are weld while applying a firm downward pressure.

given as equivalent values to the SI units. The standard sizes and dimensions used in the two systems are not identical and for Crossfiling shall not be permitted. The finished this reason conversion from a standard size of dimension in one machined, ground, or filed surface shall be smooth system will not always coincide with the standard size of dimen with all traces of weld ripple removed and shall be sion in the other. Suitable conversions encompassing standard continuous in the length where measurements are to sizes of both can be made if appropriate tolerances are applied in be taken. The width of the prepared surface shall not each case. The SI values (including tolerances) given here for filler metal diameter, length, and package size were selected to be less than 3 mm (1/8in.).**

fit the product sizes which presently are U.S. standards. Toler A4.10.5 A total of six ferrite readings shall be ances are used in some cases in this specification but not in taken on the prepared surface along the longitudinal others. In those cases where no tolerances are given, the values axis of the weld pad with an instrument calibrated in are those that would be obtained if the measurements were taken in SI units. In this specification, a covered electrode is defined accordance with the procedures specified in AWS

as follows: Covered Electrode-A composite filler-metal elec A4.2, "Standard Procedures for Calibrating Magnetic trode consisting of a core of a bare electrode or metal cored Instruments to Measure the Delta Ferrite Content of electrode to which a covering sufficient to provide a slag layer Austenitic Stainless Steel Weld Metal" (latest edition).

on the weld metal has been applied. The covering may contain A4.10.6 The six readings 'obtained shall be aver materials providing such functions as shielding from the atmos phere, deoxidation, and arc stabilization and can serve as a aged to a single value for conversion to Ferrite source of metallic additions to the weld. Number.

1.31-3

- LL

Ferrite shall be measured in this area free of arc

-H starts and craters 1 Copper bar I

I

I

25x25x75 BASE PLATE

1465 min .

1 40 -25 min o I

All dimensions in millimetres, U.S. EQUIVALENTS*

mm in.

1.6 1/16

2.0 5/64

2.4 3/32

3.2 1/8

4.0 5/32

4.8 3/16 Electrode Welding In drawing above 6.4 1/4 diameter current (approx. mm) 6 0.25 (mm) (amperes) W L 8 0.3

9.5 3/8

1.6 35-45 6 30 10 0.4

2.0 45-55 6 30 13 0.5

2.4 65-75 8 40 15 0.6

3.2 90-100 10 40 18 0.7

4.0 120-140 13 40 25 1

4.8 165-185 15 40 30 1-1/4

240-260 18 40 40 1-1/2

65 2-1/2

75 3 See Editor's Note on Page 1.31-3.

Fig 4 - Details of Weld Pad for Ferrite Test

1.31-4

Copper bars 85 long of cross section as shown in A-A' below.

Copper bar 16 high x

9.5 thick x 70 lon

g. Copper bar same

-as shown at opposite end A

I

Type 1 For 4.0 dia. Electrodes and smaller Note: All dimensions are in millimetres.

COPPER

16 BAR

U.S. EQUIVALENTS*

MM in.

T Cross Section A-A'

4.0 5/32 This design allows increased visibility,

4.8 3/16 making it easier to hold a short arc length.

9.5 3/8

16 5/8

25 1 COPPEIR COPPER

BAR BAR

70 2-3/4 25 square

85 3-3/8 Type 2

  • See Editor's Note on Page 1.31-3.

For 4.8 & larger welding electrodes and for any pads on carbon steel base plate Fig. 5 - Optional Welding Fixture for Welding Ferrite Test Pads

1.31-5


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