Steel Backing Removal prior to RT on D1.5 PQR testing.

By bmasoncoe Date 09-24-2009 20:32

I have a contractor that performed a PQR that recently failed RT. The RT film showed it as "Wagon Tracks" on both sides of the root. They have informed me that what is showing up on the RT is a gap that has developed between the plate and backing bar. The contractor has informed that they will be removing the backing and retesting. Is this acceptable? From what I understand if it fails RT than it must be restested regardless of the flaw. I can't find anywhere in the code where is states that backing can be removed prior to RT.

By CHGuilford (****)

Date 09-24-2009 21:04

It is not unusual to machine the backing off after RT has shown a failure.
It does require the consensus of the approving engineer - at least from what I've experienced. And it should be noted on the PQR so that if the PQR is used for another customer all conditions are made known.

What you may need to watch for is that the plate is not machined away to remove a defect that is actually in the test plate, and not at the root or in the backing. PQRs are done to provide mechanical test specimens but they also are supposed to demonstrate proper penetration, bead placement, and other data on how the weld was made. If a defect at the bottom of the plate is machned away, you may be masking a problem.