What are the steel pipe acceptance standards

①Steel pipe wall thickness inspection: micrometer, ultrasonic thickness gauge, no less than 8 points at both ends, and record.
②Steel pipe outer diameter and ovality inspection: caliper, vernier caliper, ring gauge, measuring point, minimum point.
③Steel pipe length inspection: steel tape measure, manual, automatic length measurement.
④Steel pipe curvature inspection: ruler, level ruler (1m), feeler gauge, fine wire to measure curvature per meter, full-length curvature.
⑤Steel pipe end face groove angle and blunt edge inspection: angle ruler, pallet.

Steel pipe surface quality inspection: 100%
①Manual naked eye inspection: lighting conditions, standards, experience, markings, steel pipe rotation.
②Non-destructive flaw detection:
a. Ultrasonic flaw detection UT: It is sensitive to surface and internal crack defects of uniform materials of various materials. Standard: GB/T5777-1996. Level: C5
b. Eddy current flaw detection ET: (electromagnetic induction) is mainly sensitive to point (hole) defects. Standard: GB/T7735-2004. Level: B
c. Magnetic particle MT and magnetic flux leakage flaw detection: magnetic flaw detection, suitable for the detection of surface and near-surface defects of ferromagnetic materials. Standard: GB/T12606-1999. Level: C4
d. Electromagnetic ultrasonic flaw detection: does not require coupling medium, and can be used for high-temperature, high-speed, rough steel pipe surface flaw detection.
e. Penetrant flaw detection: fluorescence, coloring, detection of steel pipe surface defects.

Steel pipe chemical performance inspection:
① Tensile test: measure stress and deformation, determine the strength (YS, TS) and plasticity index (A, Z) of the material longitudinal, transverse sample pipe section, arc, circular sample (￠10, ￠12.5) small diameter, thin wall large diameter, thick wall calibration distance. Note: The elongation after fracture of the sample is related to the size of the sample GB/T1760
② Impact 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)
③ Hardness test: Brinell hardness HB, Rockwell hardness HRC, Vickers hardness HV, etc.
④ Hydraulic test: test pressure, stabilization time, p=2Sδ/D

Steel pipe process performance inspection:
① Flattening test: round sample C-shaped sample (S/D＞0.15) H=（12）S/（∝S/D）. L=40～100mm unit length deformation coefficient = 0.07～0.08
② Ring pull test: L=15mm no crack is qualified
③ Expanding and curling test: the top center taper is 30°, 40°, 60°
④ Bending test: can replace the flattening test (for large diameter pipes)