Document: NRC Regulatory Guide
Document ID: c6e354c2-cc83-4d3d-b01b-b43865ccdac6
Document Type: regulatory_guide
Title: Control of Ferrite Content in Stainless Steel Weld Metal + HISTORY - HISTORY DG-1279 , Proposed Revision 4, published 09/2012 (Rev. 4)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1202/ML12024A004.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.31
CFR Part: 
CFR Title: 

Content:
d weld deposits with an absence of microfissures, the American Society of Mechanical Engineers (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 content. The study group analyzed data from welds prepared by eight different procedures. 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 content. Revision 2 (issued May 1977) and Revision 3 (issued April 1978) to this guide were based on those recommendations. Revision 2 of this guide replaced the guidance for testing production welds in Revision 1 with guidance for process control through testing weld test pads. These changes considerably reduced the testing effort needed to control delta ferrite in welds. Revision 4 updates several outdated standards and removes an appendix that has been incorporated into relevant specifications. The provisions of the ASME Boiler and Pressure Vessel Code (ASME Code) (Ref. 4) incorporated by reference into the NRC regulations require compliance with one of two alternative methods (i.e., either a chemical analysis method or a magnetic measurement method) to control delta ferrite in weld metal filler materials. The NRC staff does not consider the use of the chemical analysis method for every welding process adequate by itself to ensure controlled delta ferrite in production welds. The staff 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 components. The staff concludes that ferrite content in the weld filler metal, as depicted by a ferrite number, should be between 5 and 20. This lower limit provides sufficient ferrite to avoid