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Given the quality problem of a batch of oil and gas long radius elbow found on site, a quality sampling inspection was carried out. The quality was tested by a penetrant test, geometric dimensions measurement, chemical composition analysis, and a hardness test. Metallographic analysis was carried out about the defects found. It can be seen that no obvious abnormality was found in the profile size, remaining wall thickness, chemical composition analysis, and hardness test results of this batch of elbows. There is a longitudinal crack with a length of 10 mm on the outer surface of the pipe end of the DN50 elbow. According to anatomical analysis, this defect is a shallow crack on the outer surface, with a certain angle between the crack and the outer surface of the pipe. The maximum depth in the cross-section is 0.24 mm, and the vertical depth from the outer surface is 0.12 mm. It is speculated that these cracks occurred before solution treatment and are related to the original defects of the parent pipe or mechanical damage during cold work.
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