Question about UT testing of CJP weld
Question about UT testing of CJP weld
(OP)
I recieved an RFI for a steel frame I designed that is constructed of HSS. This frame holds salt spreaders that go in the back of dump trucks. The fabricator (who is also the erector)wants to shop build the frame in two pieces, and them ship them to the site. I think this is a good idea and have no problem with it. He will have to get permits and all that, it's his problem.
The fabricator is proposing a CJP weld at each of the 18 columns. This is fine with me as well. He has submitted several examples that demonstrate his experience in constructing similar HSS frames with field welded joints like this. He has also submitted his AWS prequalified welding procedure for the joint and the qualifications of his QC/QA personnel.
My only concern is that he states the CJP weld will not be able to be UT'd because of the minimum material thickness of 5/16". The wall thickness of the HSS is 1/4". The fabricator's QA/Safety and Quality Management Systems Director has offered to be onsite and visually inspect each pass and produce an inspection report with photos of each splice, weld layer and finish. This person is Class A-D inspector as well as trainer. Additionally the 3rd party welding inspector for the job would be on site as well for the duration.
I am not sure if this is good enough or not because my understanding is that all CJP welds have to receive more than just a visual inspection. Is there another kind of NDT that can be done for this weld?
The fabricator is proposing a CJP weld at each of the 18 columns. This is fine with me as well. He has submitted several examples that demonstrate his experience in constructing similar HSS frames with field welded joints like this. He has also submitted his AWS prequalified welding procedure for the joint and the qualifications of his QC/QA personnel.
My only concern is that he states the CJP weld will not be able to be UT'd because of the minimum material thickness of 5/16". The wall thickness of the HSS is 1/4". The fabricator's QA/Safety and Quality Management Systems Director has offered to be onsite and visually inspect each pass and produce an inspection report with photos of each splice, weld layer and finish. This person is Class A-D inspector as well as trainer. Additionally the 3rd party welding inspector for the job would be on site as well for the duration.
I am not sure if this is good enough or not because my understanding is that all CJP welds have to receive more than just a visual inspection. Is there another kind of NDT that can be done for this weld?





RE: Question about UT testing of CJP weld
Anything beyond VT should be listed on the drawings or other contract documents.
Just my two cents.
RE: Question about UT testing of CJP weld
The structural steel specifications state that CJP welds have to be inspected with UT, radiographic testing or magnetic particle inspection. I'm not sure how common the latter two methods are.
Are many welding inspectors familiar with Annex S?
RE: Question about UT testing of CJP weld
If an inspector has ever requested NDT procedures from whomever is performing the work, then I would say yes, he would be familiar.
RE: Question about UT testing of CJP weld
There is no reason not to UT the connections, but as mentioned, the procedure must be acceptable to the Engineer.
If I were involved, I would suggest the UT be conducted in accordance with JIS standards. I've used the JIS for examining rail car frames. It is different than AWS, but AWS isn't the answer in every case. JIS is based on a DAC curve that is constructed using a standard calibration block consisting of a plate with drilled hole. Easy, quick, but not exactly like AWS.
Best regards - Al
RE: Question about UT testing of CJP weld
Perhaps the ultrasonic testing is overkill for this splice. I will have to see how much tension would actually occur at the splice location.
I don't think introducing Japanese Industrial Standards would be a wise idea at this point.
Thanks for your help.
RE: Question about UT testing of CJP weld
Firstly, a piece of advice - never write UT, RT or MT in a specification as you are only going to get one thing from the contractor - MT.
UT & RT are volumetric whilst MT is a surface method examination - big difference in costs and more importantly the chances of finding internal defects in the weld.
It should be UT or RT and MT or PT (if stainless steel)
I have been involved with structural fabrication (in the Southern Hemisphere) for over 30 years and every time a contractor wants to splice something not shown on the drawings it must be examined by UT or RT and MT or PT.
There is no reason why these connections couldn't be RTed by the contractor (other than the cost due to access) but that is your call as the designer based on the criticallity of the joint.
Basically, if it falls down then it comes back to you,
Cheers,
DD
RE: Question about UT testing of CJP weld
RT of backing bar welds has the same problem; excellent welds rejected due to too much doubt.