Fred-
Your reference to Appendix XI tricked me! Fortunately I found an old (1990) copy of D1.1 and saw what you were intending. This is now Appendix I in 2006. By this method, my weld would be in "Zone 2", i.e., CE = .523 & C = .280 which then means I should use the Hardness Control method, except that my weld is a groove weld which then means I must use the Hydrogen Control method; by Hydrogen Control, I am in the Susceptability Index of F at most; for low restraint and Susceptibility of F, I should have a preheat AND interpass of at least 280 deg F.
Perhaps I misunderstand the meaning and intent of "interpass temperature".
By "required interpass temperature", am I to wait until material cools to 280 deg F before resuming the next pass? Why? Higher base metal temps are conducive to lower cooling rates, which I thought would be preferable to minimze quench hardening effects.
I understand that in PQR mode I can do anything that allows me to pass destructive tests, but am looking for basic understanding of "interpass".
Thanks
the interpass requirement is a minimum. not a max.
My reference was the 2002 Code. That is the electronic file copy I have and didn't check the latest hard copy. Minimum interpass temperature is the same as preheat and, in many Code applications is dictated by the applicable Code you are working with, although the actual qualified can be above the minimum required by the Code. Maximum interpass temperature is normally whatever you qualifiy with due consideration taken, according to the materials you are qualifying. Higher isn't always better.