Seeking help regarding the non-destructive testing of welds between branch pipe supports, 45° angled tees, and the main pipe
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Problems encountered at the construction site currently. 1. For the weld between the branch pipe fitting and the main pipe, should it be considered as a fillet weld or a branch pipe connection weld? Some people on the internet believe that for fillet welds, according to SH3501, only PT/MT testing is required. However, when the local pressure vessel inspection agency conducted the inspection, it requested that RT/UT testing be carried out again, that is, the inspection was to be done on the welds connecting the branch pipes. Can RT/UT be performed on the welds between the branch pipe supports and the main pipe? II. The Supervisor is directly welded to an inclined tube at a 45° angle, namely what is commonly known as a saddle joint. For this, according to SH3501, it should be considered as a branch pipe connection weld, and RT/UT + PT/MT inspections have been carried out; straight joints should be detectable. However, it is indeed impossible to inspect welds at 45° angles; especially the area at the 45° sharp angle (the inner side of the elbow), where the welds cannot be inspected in any way, right? There is very little information on this topic available online; I hope that the expert Hai Chuan will be kind enough to provide guidance and clarify things for me! !
I. Welds between the branch pipe fitting and the main pipe: We cannot use RT; I forgot whether to use UT or MT instead.
This post was last edited by niat8888 on 2018-8-3 07:55. I. Should the welds between the branch pipe fitting and the main pipe be considered as fillet welds or as welds for connecting branch pipes? Some people on the internet believe that for fillet welds, according to SH3501, only PT/MT testing is required. However, when the local pressure vessel inspection agency conducted the inspection, it requested that RT/UT testing be carried out again, that is, the inspection was to be done on the welds connecting the branch pipes. Can RT/UT be performed on the welds between the branch pipe supports and the main pipe? The branch pipe fitting is welded to the main pipe; this is the welding joint for connecting the branch pipes. For items inspected in accordance with the SH3501 standards, for pipelines of grade 2 and above, RT/UT testing is required. This is because, due to the structure of the branch pipe supports, the thickness differences are too large, and if the diameter is not large enough, it is difficult to apply the film properly. So, UT is easier to implement; as for testing the actual effectiveness, that’s unknown. II. The Supervisor is directly welded to an inclined tube at a 45° angle, namely what is commonly known as a saddle joint. For this, according to SH3501, it should be considered as a branch pipe connection weld, and RT/UT + PT/MT inspections have been carried out; straight joints should be detectable. However, it is indeed impossible to inspect welds at 45° angles; especially the area at the 45° sharp angle (the inner side of the elbow), where the welds cannot be inspected in any way, right? Especially in the area of the 45° acute angle, using an RT test gives poor results; the weld can barely be seen. So it can detect up to the extent that it is capable of, nothing more. If RT doesn’t work, use UT. Or RT+UT, to handle this section. This can be discussed with the supervisor first.
Thank you so much for responding patiently! ! In your opinion, both of these can technically be subjected to UT testing, but our testing facility says it’s impossible to do so under any circumstances. . . Is it because the individual’s skill level is not sufficient?
UT is indeed greatly affected by the structure, as the welds at the pipe support connections have a high probability of causing interference. Is there a source? If available, use rays; the penetration depth will then be sufficient. .