Most of the time, I get asked to just be extra alert during the continuous VT of such joints.
BUT, it is possible to UT them, there just is no pre-approved, code defined and accepted acceptance/rejection criteria outlined for them. A good conversation with your level III may be in order.
VT catches most all problems anyway, UT is just confirmation. It also makes sense when the inspector is watching too many welders on one job and can't see every pass.
Have a Great Day, Brent
Thanks Brent. Can you please briefly explain how to go about UT'ing them? Also, is there a reference somewhere in D1.1 that indicates UT limits based on material thickness? I've always been told that UT can't be done on material 5/16 thick or less, but I've never bothered to research it as to why.
You are talking to a non NDT guy. I am studying for both my MT & UT but am not even close at this point. I am just going by what both my Level II and III people I work with regularly have told me. Several other Level III's have told me the same thing through the years.
I'll see what I can find but hopefully someone else with precise knowledge with chime in.
Have a Great Day, Brent
I'm under the understanding that you can UT material thinner than 5/16, if you have an approved procedure written by a Level 3.
Per D1.1:2010; 6.20, "For thicknesses less than 5/16 in [8mm] or greater thatn 8 in [200mm], testing shall be performed in conformance with Annex S."
Annex S describes alternative UT inspection techniques, and how to document them
Not sure how a Mandatory Clause can apply the word shall to enforce an informative clause that is listed as not part of the code, but thats how it is
Interesting. Thanks for that input. I will be checking that one out.
Have a Great Day, Brent
Yeah, the Annex S deal is non-trivial, plan on spending more than a few bux if you go this route
I have witnessed a couple of the frauds as well. They have not developed a procedure at all for the thin members but they smear some couplant on the joint, run the transducer over it and call it good so they can collect their money.
I do know a couple though who have procedures established and the engineers have approved them for examining the joint.
You don't have to redo it for every job do you? Once established the paperwork documenting the procedures can be submitted and then it's up to the engineer? Seems like it would be worth it for most UT companies to go through the process and have that available to them so they could prove they could do the exam with reasonable competence.
Have a Great Day, Brent
The last time this happened to me, I sent a letter to the EOR, pointed out the limits in Part F, and also that a qualified procedure would need to be reviewed and accepted by his office. He backed off quick. By the way, it was a splice in some 1/4" wall HSS that had been RFId, and I watched every pass.
Not all forms of UT should use side drilled holes, especially on thinner members. A Distance Amplitude Curve is also not necessarily the way to go either. There are numerous ways to get meaningful UT, all of them based on the flaw type, shape, location, size, and orientation deemed rejectable by the design engineer. On thinner members, planar flaws connected to a surface, or near surface are usually critical.
You are correct regarding the frauds. However, that does not relieve the engineer from his or her responsibilities. If that engineer is stupid enough to white wash something like that, was it the LIII that was a fraud, or was it the engineer?
Regarding time, that is dependent upon the experience level and abilities of the level III.
You bring up some good points Gerald.
Scott, the main problem with materials under 5/16" in thickness is that D1.1 Table 6.2 or 6.3 doesn't list any acceptance or rejection criteria for anything less than 5/16". Another problem is when you use the transducers sizes, frequency, and angle spelled out in Clause 6 of D1.1 you end up having a hard time distinguishing the signal where the sound is entering the material and any other reflections between the backwall due to them being right up ontop of each other on the screen. And with the gain turned up at the scan level shown in the table in Clause 6, it is mostly grass on the screen and easy for something to be hiding in there and be missed.
Everyone should remember that AWS Clause 6 does not specify the NDT it states that "when required" these are the techniques and standards. Just like a WPS, UT has prequalified procedures, Claus F, the annex provides provisions for qualifying a UT procedure where parameters fall outside Clause F.
Other standards mandate the NDT, such as AISC, it states 5/16 inch and greater requires UT, then states materials less then 5/16, UT "is not required". It is the responsibility of the Engineer to specify the majority of the NDT, this is the intent of AWS D1.1.
So the individual stating you can't UT those ranges is wrong but right, he really means it is "not required" if it is for structural, so it is dependent on the Industry and code required.
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