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When the reserve clearance at both ends is small, due to the structural reasons of the detection device, both ends of the head may not be effectively detected, and the tip is the most likely to have cracks or other defects. If there is a potential for cracking at the tip, the welding heat effect at the time of installation may also cause potential crack propagation. Therefore, it should also pay attention to the detection of certain areas of the seamless steel pipe after welding, and timely discover the expansion of the steel pipe end head defects.
Austenitic seamless steel pipe line, when the insulating layer may be damaged or infiltrated the site of rainwater, to be noted that infiltration detection to detect stress corrosion cracking or pitting defects.
However, the magnetic particle or penetrant test can only detect the outer surface of the steel pipe, and it is incapable of acting on the defect of the inner surface. The detection of the inner surface, in particular the detection of crack-like defects, must be carried out by ultrasonic testing.
Common defects in seamless steel tubes for magnetic particle testing or penetrant testing
Magnetic particle testing or penetrant testing can effectively find surface defects such as surface cracks, folds, heavy skins, hair lines, and pinholes. For ferromagnetic materials, the magnetic particle detection method should be preferred because of its high detection sensitivity; for non-ferromagnetic materials, such as stainless steel seamless steel tubes, penetration testing methods are used.