Seamless common pitfalls magnetic particle testing or penetrant testing

Magnetic particle testing or penetrant testing can effectively find surface cracks, folds, double skin, hairline, pinholes and other surface defects. For ferromagnetic materials, magnetic particle inspection method should be preferred, because of its high detection sensitivity; For non-ferromagnetic material, such as stainless steel seamless pipe, then a penetration assay.

Reserved resection margin when both ends is small, causes the detection apparatus, both ends of the head may not be effectively detected, and ends there is most likely the site of cracks or other defects. If there is a potential end tendency to crack, the installation of the weld heat affected also possible to make the potential crack. Therefore, it should be noted that certain areas of the welded steel tube detection, to detect defects in steel tip extensions. Use the online austenitic seamless insulation is damaged or when rain may have infiltrated the site, should pay attention to the infiltration testing to find stress corrosion cracking or pitting corrosion and other defects. However, magnetic particle or penetrant testing can only detect the outer surface of the steel pipe, internal and surface defects are powerless. Inner surface of the test, especially crack class defect detection through ultrasonic testing must be carried out.