American Welding Society Forum
While performing a series of welder qualification tests - and opting for Radiographic evaluation in lieu of bend tests it was determined that a number of welder qualification test failed criteria of RT testing. It was suggested that we throw out or ignore the failures of RT testing and perform bend tests on those plates in question. If they pass bends , then they would pass qualification against the original failure of RT testing. This doesn't feel right... In my opinion - the initial failure using radiography would put this into an immediate retest in my mind,, in which TWO new tests welds are needed to negate the initial failure........ opinions, thoughts or other comments are welcome here please.
Try this thread and see if it answers your question. Title: RT vs. bendhttps://app.aws.org/forum/topic_show.pl?tid=33895
Pretty much the same situation and a lot more information than I could hope to repeat here.
He Is In Control, Have a Great Day, Brent
I was administering some welder qualification tests in the past and several of my best welders failed RT with a line running nearly the length of the plate at the edge of the root opening at the b/up strip. I suspected the plate and b/up strip had a slight gap and the film was showing the bleed through under the b/up. My discussion with the tech doing the RT interpretation got me nowhere. I personally removed the b/up strip and found my suspicion true, I ground the joint flush (not beyond) and as an experiment resubmitted two plates and both passed with flying colors.
I retested the operators and submitted plates without backing for RT from then on.
In other words, the welders didn't completely fuse the weld to the backing. They failed the test, short and sweet. If the plates are submitted for RT evaluation, the backing is suppose to be intact and 3" wide rather than 1 inch if D1.1 is the governing standard.
Best regards - Al
The weld tests had 3" backing, the root was clearly fused, the line was 1/16" apprx' outside where the root should be.
it appeared to be excess material that bled under the b/up strip away from the root.
I had previously discussed with the owner (a level III) of the test facility whether to remove the backing prior to submission of the plates. He told me they could be removed, but did not need to be due to their size.(3") The b/up would not interfere with the welds location.
Here is a similar post from 10-8-14:
(Our track marks were clearly not undercut though.)
Non-relevant indications are common in radiographic examination of groove welds with backing. If the backing is not fit up very tight (<0.015" clearance) to the base metal, an undercut can occur at each side of the root pass, which looks like lack of penetration or lack of fusion on the radiographic film. This indication is common enough that it has its own name, "railroad tracks." It sounds like this condition was verified, when the contractor "cut several of the coupons." I would like to see photos of the coupon cross section and copies of the rejected film, if they are available.
Although AWS D1.1, Table 4.11 specifies bend tests to qualify welders, and although Table 4.11, note b allows radiography in lieu of bend tests, it is inappropriate to nullify a rejected radiograph with a bend test. AWS D1.1, Paragraph 6.17.3 indicates that the correct way to evaluate a possible non-relevant indication due to surface conditions would be to blend the surface and reinspect, because the surface condition "may cause objectionable weld discontinuities to be obscured in the radiograph." In this case, the contractor should remove the backing ring and blend per AWS D1.1, Paragraph 220.127.116.11, without violating minimum wall, and perform a new radiographic examination. If the indication is truly non-relevant, the new radiography will not show the previous indication.
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