About two years ago the company I work for had to requal all its CS plate welding procedures to satisfy DNV as to the applicability of our procedures to the actual welding in production. DNV was correct, the procedures we were using didn't relate to what we were doing very well. We make units with a framework of square tubing and at that time we were using procedures back gouged and welded from both sides. All our procedures were upgraded to CJP welded from one side only, and were done with charpies because we have some contracts that call for impacts. In the ensuing period, I learned that tubular welding requires procedure and welder qualification on tubular which I am now pitching to the boss (even though ,surprisingly, we have never had any issue with third parties or customers about using the plate procedures, not even a comment, my guess is its just a matter of time). Here's the crux of my question: When we did WPS qualifications the last time, DNV would only accept thickness limits for impacts that tracked the ASME thickness limits. Our consulting welding engineer acquiesced even though I raised the question at the time, and wrote up the procedures with ASME thickness limits for impacts. Having learned a bit more and having examined section 4 of D1.1 in some detail, I can't find any basis for the imposition of ASME limits regarding thickness in an AWS qualified WPS. My reading of section 4 finds no difference between the WPS thickness limits and thickness limits of the same WPS with impacts. It would sure be a lot easier to pitch switching to a tube based procedure for our TKY production welding if we had to qualify at most 2 WPS's and could cover all our various thickness ranges and tube sizes by running 6GR tests rather than the dozen plate tests we ran because of the previously imposed charpy thickness limits.