Alloy 600 and its associated weld metals (Alloys 82, 182, and 132) have been used extensively for nuclear power plant construction. These alloys are known to be susceptible to primary water stress corrosion cracking (PWSCC), and reference crack growth rate (CGR) equations for this degradation mechanism were first incorporated into the ASME Boiler and Pressure Vessel Code in the 2009 Addenda of the 2007 Edition via Section XI, Nonmandatory Appendix C. These original equations were developed from a large dataset to which numerous international laboratories contributed. It was reviewed and assessed by an Expert Panel. In 2015, another Expert Panel was organized, including members from the original Expert Panel. Publicly available data produced since the first equations were developed, and data that had not been part of the original model development process, were collected. The data were screened for testing quality and plant applicability by the Expert Panel, and new PWSCC equations were developed. This paper summarizes the development of the revised PWSCC equations for Alloy 600 and Alloy 82/182/132 to support revision of the equations previously incorporated into Appendix C of ASME B&PV Code Section XI.