Rationale

The Nippon Steel and Sumitomo Metals Corporation (NSSMC has developed a new stainless steel grade 317AP that provides improved corrosion resistance to polythionic acid corrosion and naphthenic acid corrosion in refinery service. The NSSMC has prepared supporting information for incorporating this grade in specification A 213. A user has requested that the new NSSMC grade, called 317AP, is considered for inclusion in A213 and other stainless steel specifications.