Progressive sampling B31.3

By dileepmarath Date 12-14-2017 11:43

Do the code demand for two penalty joints for a different welder (say Welder # 2)who also had welded a penalty joint for original welder (Welder # 1)

To describe : one joint was taken radiography for welder # 1 and found is to be repaired. Two penalties are assigned out of which one joint is accepted and the other joint is a repair, but that portion was welded by welder # 2. the portion welded by welder # 1 is acceptable. Do the code demand for penalty for Welder # 2?

In my opinion, it does not need any more penalties as we were analysing the lot of welder # 1. We will have a separate lot for welder # 2 which may have already accepted(which includes this joint as well)

Please correct me if I am wrong!

By Maggs47 (**)

Date 12-14-2017 15:21

Perhaps I don't know enough details of B31.3, but why are you testing welder #2's work at all to qualify welder #1? Shouldn't welder #1 be welding complete their own tests?

By dileepmarath Date 12-16-2017 03:21

Some joints will be welded by two welders or more. When we take samples, we are forced to take radiography of portions welded by other welders

By 803056

Date 12-16-2017 14:22 Edited 12-16-2017 14:31

If the welders are qualified using a common coupon, they both pass or they both fail.

Did I understand your question?

If the issue is a production weld, progressive examination is intended to ensure the joint or portion if the joint that failed are "flukes" and the repair isn't confined to the portion of weld that failed. Progressive examination requires additional lengths of joint be examined to ensure the unacceptable condition was in fact isolated to the area that was examined. Examining additional regions to either side ensures the remained of the joint is sound. One must remember, progressive examination, like random spot examination is only looking at a discrete portion of the weld. It is a "statistical" quality control method.

I have had projects were the contractor dictated what areas were to be examined. Of course, it wasn't surprising when those particular areas passed. The owner got wind of what was happening and demanded random spot examination where the owner selected the random locations. The results were 100% reject. None of the welds were back gouged, all the welds exhibited incomplete joint penetration. Progressive examination resulted in 100% examination. It was a case where the contractor was not negligent, it was a case of fraud.

As for penalizing the welder, that is a company issue, not a code issue unless it is addressed in the project specification.

Al

By dileepmarath Date 12-17-2017 13:04

I think you haven't understood my question properly.
first - its not welder qualification test

its production weld. so when we are testing a welder as per progressive sampling why is the need of considering a repair of another welder (he will have another lot under testing). These are totally random and is marked by the client through a software.

The code clearly says that a RE-Repair does not need any more penalty joints. I think it must be same when considering the welder in taking radiography of penalty joints.