Seamless Steel Tube Common Defects on Magnetic Particle Detection or Penetration Testing

Magnetic particle testing or penetrant penetration testing can effectively detect surface defects such as surface cracks, folds, heavy skins, hairline, and pinholes. For ferromagnetic materials, magnetic particle inspection methods should be given priority because of their high detection sensitivity; for non-ferromagnetic materials, such as stainless steel seamless tubes, permeation testing is used.


When the cut-off margin at both ends is small, both ends cannot be effectively detected due to the structure of the detection device, and the end is the portion where cracks or other defects are most likely to occur. If there is a propensity for potential crack tip, the installation of a welding heat effect may also be a potential crack growth. Therefore, we must also pay attention to the detection of defects in the expansion of the steel pipe head after a certain area of seamless steel pipe is tested.


Regarding the use of austenitic seamless steel tubes, when the insulation layer is damaged or rainwater may infiltrate, the penetration and penetration test should be paid attention to to find the defects such as stress corrosion cracking or pitting corrosion.


However, the detection of magnetic powder or osmotic penetration can only detect the outer surface of the steel tube, and the inner surface of the defect is incompetent. The detection of the inner surface, in particular the detection of crack-like defects, must be achieved by ultrasonic testing.