Lets take a short walk in history to explain that one. In Article 7 1974 edition of ASME Section V (first full edition if I am not mistaken) It states T-721 surface preparation (A) "however, surface preparation by grinding or machining may be necessary in some cases where surface irregularities would otherwise mask the indication of discontinuities"
So what did they mean by that..At the time ASTM held a lot more sway than it does now. E109-63 and reapproved in 71 and referenced in SE 109 74 was still in effect. In it, it states: If surface is unusually rough, such as with burned in sand, or a very rough weld bead, interpretation may be difficult because the powder is being trapped mechanically. In case of doubt a light grind may be necessary to dtermine if actual indications are present. "
Going to Summer 73 section III mandatory appendix 9 it states the same as ASME V except the last sentence is changed to "mask the indication of unacceptable discontinuities".
Summer 73 B31.1 Kicks to 71 Section VIII, which kicks to E109 (see above)
Don't know about you, but I am seeing a pattern here.
Last but not least, the first edition of AWS D1.1 1972 also kicks you back to E109.
It is clear that historically speaking, the intent was remove it to the extent that would allow examination without being potentially masked or confused.
Lets fast forward:
In 1976, E109 Was superceded by E709:
9.2 Cleaning Examination Surface—Cleaning of the examination
surface may be accomplished by detergents, organic
solvents, or mechanical means. As-welded, as-rolled, as-cast,
or as-forged surfaces are generally satisfactory, but if the
surface is unusually nonuniform, as with burned-in sand, a very
rough weld deposit, or scale, interpretation may be difficult
because of mechanical entrapment of the magnetic particles. In
case of doubt, any questionable area should be recleaned and
reexamined
It is not as clearly stated as earlier versions, but it is clear the intent is the same. People can go around the hedgerow all day and its still going to come back to the same thing regardless of AWS, ASME, etc codes.
Regards,
Gerald
Thank you for the reply CWI.
If you dont mind I'd like to expand on my question and give further background and where I am going with this. It seems that within my organization, Welders, Inspectors, and level III inspectors are in a constant battle over surface preparation after welding for MT inspection. Because we lay millions of welds over every joint configuration imaginable you can see why this topic is so important. The concerns are; Cost and time that the welder has to prep the weld for inspection, Over grinding thus, removing the ability to perform relevancy checks, inspectors having the welders over grind welds such that there is no possibility that a level III audit on his inpection will reveal anything, either relevant or non-relevant.
The concerns are; Cost and time that the welder has to prep the weld for inspection, Over grinding thus, removing the ability to perform relevancy checks, inspectors having the welders over grind welds such that there is no possibility that a level III audit on his inpection will reveal anything, either relevant or non-relevant.
It is irrelevant if the indication cannot be confused with a ‘rejectable’ indication. Making them grind out known non relevant indications is over the line, as is making them grind out relevant indications that are not rejectable. That is not the codes intent of that I am sure.
From where I read this, it sounds more like you may have a visual inspection problem. It takes a lot to create masking indications for MT.
Conversely, If the welders are putting in excessively ropy beads, and other conditions that can in fact mask, then you have another problem.
Either way, it sounds like you have a problem that is not going to get fixed by internal personnel if there is as much bickering as you are making out going on.
You may have to contract an outside consultant to tune up all parties concerned.
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