Thanks everyone. We are having them take a test coupon and do a tensile test. Additionally, I found some information much like that in the Mittal steel brochure in an old Lukens catalog using the Larson Miller Parameter. I'll let everyone know what happens. Thanks again for everyone's input.
Can anyone give me any info. on how Tensile stress is affected after multiple PWHT's. I have a vessel (SA-516-70), that due to poor QA/QC and carelessness will have to go through a 3rd heat treatment. Any help will be appreciated.