Inspection standard of seamless steel pipe

Steel pipe geometry and shape inspection:

① Inspection of steel pipe wall thickness: micrometer, ultrasonic thickness gauge, no less than 8 points at both ends and record.

②Examination of steel pipe outer diameter and ovality: caliper, vernier caliper, ring gauge, measure the maximum and minimum points.

③ Steel pipe length inspection: steel tape measure, manual and automatic length measurement.

④ Inspection of steel pipe curvature: straightedge, level (1m), feeler gauge, thin wire to measure curvature per meter and full length curvature.

⑤ Inspection of bevel angle and blunt edge of steel pipe end face:


Square, card board. Steel pipe surface quality inspection: 100%

① Manual visual inspection: lighting conditions, standards, experience, signs, steel pipe rotation.

②Non-destructive inspection:

  1. Ultrasonic flaw detection UT: It is more sensitive to the surface and internal crack defects of various materials with uniform materials.

Standard: GB/T 5777-1996 Level: C5

  1. Eddy current flaw detection ET: (electromagnetic induction) is mainly sensitive to point-shaped (hole-shaped) defects.

Standard: GB/T 7735-2004 Level: Level B

  1. Magnetic powder MT and magnetic flux leakage inspection: magnetic inspection, suitable for the detection of surface and near surface defects of ferromagnetic materials. Standard: GB/T 12606-1999 Level: C4
  2. Electromagnetic ultrasonic flaw detection: No coupling medium is required, and it can be applied to high temperature, high speed, rough surface flaw detection of steel pipes.
  3. Penetration inspection: fluorescence, coloring, and detection of surface defects of steel pipes.


Steel management performance inspection:

①Tensile test: measure the stress and deformation, determine the strength (YS, TS) and plasticity index (A, Z) of the material, longitudinal and transverse sample tube sections, arc, round sample (¢10, ¢12.5) small diameter , Thin-walled large-diameter, thick-walled calibration distance. Note: The elongation of the sample after breaking is related to the size of the sample GB/T 1760

②Impact test: CVN, notch C type, V type, work J value J/cm2 standard sample 10×10×55(mm) non-standard sample 5×10×55(mm) ③Hardness test: Brinell hardness HB , Rockwell hardness HRC, Vickers hardness HV, etc. ④Hydraulic test: test pressure, voltage stabilization time, p=2Sδ/D


Steel pipe process performance inspection: ① Flattening test: round specimen C-shaped specimen (S/D>0.15) H=(1+2)S/(∝+S/D)L=40~100mm deformation coefficient per unit length =0.07~0.08 ②Ring test: L=15mm, no cracks are qualified ③Flaring and crimping test: the top center taper is 30°, 40°, 60° ④Bending test: Can replace flattening test



ASTM A500 is a carbon steel cold-formed round section and special-shaped section welded square pipe and seamless square pipe for structural use.


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