Are there any things to keep in mind when measuring pipeline thickness?
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For pipeline thickness measurement, is it still necessary to obtain data when leaks have already occurred at certain welds?
I’ve encountered a few cases where the pipes were leaking, but thickness testing couldn’t detect the issue; in one case, there was a sand hole in the weld of the pipe, which caused leakage, yet thickness testing was ineffective in identifying this problem. In the second case, the pipe leaks due to local corrosion (corrosion pits with a diameter of about 2–3 mm), and thickness measurement cannot detect this issue, even if the measurement site is very close to the leak point. The third scenario is cracking; thickness testing will not reveal any abnormalities. In my opinion, it is first necessary to determine the cause of the leakage and the pattern of failure, in order to use appropriate non-destructive testing methods for detection. For example, if it is a local corrosion pit, phased array corrosion scanning or DR can be used; if it is a sand hole in a weld, DR or conventional RT can be employed. If it is a crack in the weld or base metal, UT oblique probes can be used for detection. But in the case of erosion or uniform corrosion, thickness measurement is a very simple and effective method.