Basic principles of test and inspection for seamless steel pipe

Seamless steel pipe is a kind of high precision steel tube material after cold drawing or hot rolling. Because the inner and outer walls of seamless steel pipe have no oxide layer, no leakage under high pressure, high precision, high finish, no deformation in cold bending, flattening and no cracks, magnetic particle testing or penetration testing can effectively find surface cracks, folding, heavy skin, wrinkles, pinholes and other surface defects. For ferromagnetic materials, magnetic particle testing should be preferred because of its high detection sensitivity; for non-ferromagnetic materials, such as stainless steel seamless steel pipe, penetration testing method should be used.

　　When the reserved resection margin at both ends is small, due to the structural reasons of the detection device, sometimes the two ends can not be effectively detected, and the end is the most likely place to have cracks or other defects. If there is a potential crack tendency at the end, the welding heat effect during installation may also cause the potential crack propagation. Therefore, attention should also be paid to the detection of a certain area of  EN 10025 S235JR Seamless Steel Pipe, timely detection of the expansion of pipe end defects.

　　For on-line use of austenitic seamless steel pipes, when the insulation is damaged or there may be infiltration of rain water, attention should be paid to penetration testing to find stress corrosion cracks or pitting corrosion defects.