Maximum hardness value for P1 materials Maximum hardness value for P1 materials afarboudi (Mechanical) (OP) 19 Jan 16 05:05 I need a code or standard specify the maximum value of hardness after PWHT on P1 materials. In many specs. it is 200 BHN but no official reference has been mentioned. RE: Maximum hardness value for P1 materials SJones (Petroleum) 19 Jan 16 14:12 NACE MR0103, 2.1.7/ ISO 17945, 188.8.131.52 for stress relief of cold formed items Steve Jones Corrosion Management Consultant http://www.linkedin.com/pub/8/83b/b04 All answers are personal opinions only and are in no way connected with any employer. RE: Maximum hardness value for P1 materials DVWE (Petroleum) 19 Jan 16 16:14 NACE SP 0472 API RP 582 These are recommended practices and standard practices. I believe they limit the hardness to 200 BHN in cracking environments, otherwise it is 225 BHN.