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Ultrasonic testing does not apply to Partial Penetration groove welds (PPW), due to the loss of the sound beam at or below the root of the weld, in the un-welded portion of the joint. If it is a Client requirement then this should be stated on some specifications in detail along with acceptance criteria.
While UT cannot be used to evaluate the weld itself, it will only detect the root, and this information can be used to determine the depth of the PP groove weld. In this case, UT could be deemed effective, but for root depth determination only.