① Inspection of steel pipe end bevel angle and blunt edge: square ruler and clamping plate.
② Steel pipe bending inspection: Use a ruler, level (1m), feeler gauge, and thin wire to measure the bending per meter and the entire length.
③Steel pipe length inspection: steel tape measure, manual and automatic length measurement.
④ Check the outer diameter and ovality of the steel pipe: use snap gauges, vernier calipers, and ring gauges to measure the maximum and minimum points.
Seamless steel pipes are widely used in daily life, but many friends do not understand the quality inspection methods of seamless steel pipes. Below, the editor and friends will learn about several basic methods of seamless steel pipe inspections.
1. Steel pipe geometric dimensions and appearance inspection:
① Inspection of steel pipe end bevel angle and blunt edge: square ruler and clamping plate.
② Steel pipe bending inspection: Use a ruler, level (1m), feeler gauge, and thin wire to measure the bending per meter and the entire length.
③Steel pipe length inspection: steel tape measure, manual and automatic length measurement.
④ Check the outer diameter and ovality of the steel pipe: use snap gauges, vernier calipers, and ring gauges to measure the maximum and minimum points.
⑤ Inspection of steel pipe wall thickness: micrometer, ultrasonic thickness gauge, no less than 8 points at both ends and recorded.
2. Chemical composition analysis: chemical analysis method, instrumental analysis method (infrared C-S instrument, direct reading spectrometer, zcP, etc.).
①N-0 meter: gas content analysis N, O
②Direct reading spectrometer: C, Si, Mn, P, S, Cr, Mo, Ni, Cn, A1, W, V, Ti, B, Nb, As, Sn, Sb, Pb, Bi in bulk samples
③Infrared C-S meter: Analyze ferroalloys, steelmaking raw materials, and C and S elements in steel.
3. Steel management performance inspection:
①Hardness test: Brinell hardness HB, Rockwell hardness HRC, Vickers hardness HV, etc.
Note: The elongation of the sample after breaking is related to the size of the sample GB/T 1760
②Impact test: CVN, notched C-type, V-type, work J value J/cm2
Standard sample 10×10×55 (mm) Non-standard sample 5×10×55 (mm)
③ Tensile test: measure stress and deformation, and determine the strength (YS, TS) and plasticity index (A, Z) of the material. Longitudinal and transverse sample pipe sections, arc-shaped and circular samples (￠10, ￠12.5) diameter, Thin wall with large diameter and thick wall with fixed gauge length.
④Hydraulic test: test pressure, pressure stabilization time, p=2Sδ/D
4. Steel pipe surface quality inspection: 100%
① Manual visual inspection: lighting conditions, standards, experience, markings, steel pipe rotation.
②Non-destructive testing inspection:
a. Eddy current flaw detection ET: (electromagnetic induction)
Mainly sensitive to point-like (hole-shaped) defects. Standard: GB/T 7735-2004 Level: Level B
b. Ultrasonic flaw detection UT:
It is sensitive to surface and internal crack defects of uniform materials of various materials.
Standard: GB/T 5777-1996 Level: C5
c. Magnetic particle MT and magnetic flux leakage inspection: Magnetic inspection is suitable for detecting surface and near-surface defects of ferromagnetic materials.
Standard: GB/T 12606-1999 Level: C4
d. Electromagnetic ultrasonic flaw detection:
No coupling medium is required, and it can be used for surface flaw detection of high-temperature, high-speed, rough steel pipes.
e. Penetrant inspection:
Fluorescence, coloring, and detection of surface defects in steel pipes.
