Seamless steel pipe quality inspection methods:
1. Chemical composition analysis: chemical analysis method, instrumental analysis method (infrared C-S analyzer, direct reading spectrometer, zcP, etc.).
① Infrared C-S analyzer: analyzes C and S elements in ferroalloys and steelmaking raw materials.
② Direct reading spectrometer: C, Si, Mn, P, S, Cr, Mo, Ni, Cn, Al, W, V, Ti, B, Nb, As, Sn, Sb, Pb, Bi in bulk samples.
③ N-O analyzer: gas content analysis of N and O.
2. Geometric dimensions and appearance inspection of steel pipes:
① Steel pipe wall thickness inspection: micrometer and ultrasonic thickness gauge; at least 8 points at both ends should be recorded.
② Steel pipe outer diameter and ovality inspection: caliper gauge and vernier caliper; measure the maximum and minimum points.
③ Steel pipe length inspection: steel tape measure; manual or automatic length measurement.
④ Steel pipe curvature inspection: straightedge level (1m), feeler gauge; measure curvature per meter and total length curvature.
⑤ Steel pipe end face bevel angle and blunt edge inspection: angle ruler and template.
3. Surface quality inspection of steel pipes: 100%
① Manual visual inspection: lighting conditions, standards, experience, markings; rotating the steel pipe.
② Non-destructive testing:
a. Ultrasonic testing (UT):
Sensitive to surface and internal crack defects in various uniformly material types.
Standard: GB/T 5777-1996 Level: C5
b. Eddy current testing (ET): (electromagnetic induction)
Mainly sensitive to point-like (hole-shaped) defects. Standard: GB/T 7735-2004
(Level: B)
c. Magnetic particle testing (MT) and leakage magnetic testing:
(Magnetic force testing) suitable for detecting surface and near-surface defects in ferromagnetic materials.
(Standard: GB/T 12606-1999 Level: C4)
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