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WELDING: NDT Methods for PJP Weld

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Greetings, friends.


We originally required on our drawings/specs using radiography (RT) for acceptance of a 1/2" effective throat PJP tubular girth butt weld. Subsquently the contractor requested that we accept ultrasonic (UT) testing. We accepted.


Still later, they asked again if magnetic particle (MT) would be good. That's where we drew the line in the sand. Personally I've never seen MT used except for non-butt welds (e.g. fillet), but beyond that we just don't see the purpose.


The contractor insisted their "Level III NDT tech" claims that UT for PJP is "not allowed" by AWS D1.1:2008. I could find no such prohibition, and in fact Part F talks about UT of groove welds, and does not distinguish between PJP and CJP, only that the minimum weld thickness must be 5/16".


They have backed off on that claim, but now insist that WE must provide an acceptability criterion for the UT. To me, it ought to say "we've got at least 1/2" of sound weld metal in there," and that's that, but I recognize there might be other issues that need addressing, such as imperfections not related to inclusion like a cold-crack or some such.


Has anyone got any experience with UT of butt welds, and did you deal with acceptability?