1. Chemical composition analysis: chemical analysis method, instrumental analysis method (infrared C-S instrument, direct reading spectrometer, zcP, etc.).
① Infrared C-S instrument: analysis of ferroalloys, steelmaking raw materials, C and S elements in steel.
② Direct reading spectrometer: C, Si, Mn, P, S, Cr, Mo, Ni, Cn, A1, W, V, Ti, B, Nb, As, Sn, Sb, Pb, Bi in block samples
③ N-0 instrument: gas content analysis N, O
2. Steel pipe geometric dimensions and appearance inspection:
① Steel pipe wall thickness inspection: micrometer, ultrasonic thickness gauge, no less than 8 points at both ends and record.
② Steel pipe outer diameter and ovality inspection: caliper, vernier caliper, ring gauge, measure the maximum point and minimum point.
③ Steel pipe length inspection: steel tape measure, manual, automatic length measurement.
④ Inspection of steel pipe curvature: ruler, level ruler (1m), feeler gauge, fine wire to measure curvature per meter and full length curvature.
⑤ Inspection of steel pipe end bevel angle and blunt edge: angle ruler, pallet.
3. Inspection of steel pipe surface quality: 100%
① Manual visual inspection: lighting conditions, standards, experience, markings, steel pipe rotation.
② Nondestructive testing:
a. 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
b. Eddy current flaw detection ET: (electromagnetic induction)
It is mainly sensitive to point-shaped (hole-shaped) defects. Standard: GB/T 7735-2004
Level: B
c. Magnetic powder MT and magnetic leakage flaw detection:
Magnetic flaw detection is suitable for the detection of 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 applied to high-temperature, high-speed, rough steel pipe surface flaw detection.
e. Penetrant flaw detection:
Fluorescence, coloring, detection of steel pipe surface defects.
4. 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 test specimens, pipe sections, arc-shaped, circular test specimens (￠10, ￠12.5)
Small-diameter thin-walled steel pipes, large-diameter thick-walled steel pipes, fixed-calibration distances.
Note: The elongation after fracture of the sample is related to the size of the sample GB/T 1760
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
5. Process of steel pipe process performance inspection:
① Flattening test: round specimen C-shaped specimen (S/D greater than 0.15) H=(1+2)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 Expansion and curling test: The top taper is 30°, 40°, 60°
④ Bending test: It can replace the flattening test (for large diameter pipes)
6. Metallographic analysis of steel pipe:
① High magnification inspection (microscopic analysis): non-metallic inclusions 100x GB/T 10561 Grain size: grade, grade difference
Organization: M, B, S, T, P, F, A-S
Decarburized layer: inside and outside.
A method rating: Class A-sulfide Class B-oxide Class C-silicate D-spherical oxide DS class.
② Low-power test (macro analysis): naked eye, magnifying glass 10x or less.
a. Acid etching test method.
b. Sulfur print test method for tube blank inspection, showing low-power organization and defects, such as looseness, segregation, subcutaneous bubbles, skin folding, white spots, inclusions, etc.
c. Pyramidal hairline test method: test the number, length and distribution of hairlines.
