Magnetic particle inspection or penetration testing of high-precision cold drawn pipes can find surface defects, such as surface cracks, creases, thick skin, hair lines, pinholes, etc. For ferromagnetic materials, due to the high sensitivity of magnetic particle inspection, the method of magnetic particle inspection should be selected. For non-ferromagnetic materials, penetrant detection methods can be used.
When the insulating layer is damaged or rainwater may penetrate, attention should be paid to penetration testing to find defects such as stress corrosion cracking or pitting corrosion. When the margin of the two ends of the high-precision cold drawn pipe is small, sometimes the ends of the two ends cannot be detected due to the structure of the detection device, and the ends may be cracks or other defective parts.
If there is a potential for cracking, the welding heat effect during the installation process may also lead to potential crack propagation. Therefore, attention should also be paid to the inspection of the area of the high-precision cold drawn pipe after the butt joint , and the expansion of the defects at the end of the pipe should be found in time.
The welding strength and toughness of high-precision cold drawn pipes are usually not as good as those of the pipe body. The quality of the inner surface is related to the frequency, and there are many burrs. Therefore, most chemical and thermal pipelines with air tightness and pressure requirements use this steel pipe. Thickness is generally divided into three types: ≤16mm,> 16-30mm;> 30mm.
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