Ni-based Alloy 600 and its associated weld metals (Alloys 82, 182, 132, and variants) have been used in service for a very long time, and a primary water stress corrosion cracking (PWSCC) model has been in the ASME Boiler and Pressure Vessel Code since 2002. The original model was based on a large collection of datasets, reviewed and processed by an Expert Panel, with details documented in MRP-55 and MRP-115. Recently, in 2015, a new Expert Panel was organized, and all the available data were collected, which comprised a database more than double the size of the original database. The datasets were obtained from laboratories around the world, which were compiled and screened for data quality and plant applicability by the expert panel.

The additional data allowed for important updates of the models, for both base metal and welds. For example, the assumed threshold for cracking in Alloy 600 was removed, and the effect of hydrogen on crack growth rate can now be quantitatively modeled. This paper provides a summary of the effort to revise the predicted PWSCC growth rates of Alloy 600 and its welds, as well as the technical basis for eventual revision of Appendix C of ASME Section XI.

 


Technical Basis for Revision to Asme Section Xi Appendix C for Stress Corrosion Crack Growth Rate Equations for Alloy 600 and Associated Welds

Division / Sponsors: 
Pressure Vessels & Piping (PVP)


Paper Proceedings: https://asmedigitalcollection.asme.org/PVP/PVP2020/volume/83815

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