Seamless steel pipe quality inspection methods

Seamless steel pipe quality inspection methods 1. Chemical composition analysis: chemical analysis method, instrumental analysis method (infrared C-S instrument, direct reading spectrometer, zcP, etc.). ① Infrared C-S meter: Analyze ferroalloys, steelmaking raw materials, and C and S elements in steel. 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. ③N-0 meter: A gas content analysis of N and 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 recorded. ② Steel pipe outer diameter and ovality inspection: caliper, vernier caliper, ring gauge, measure the maximum point and minimum point. ③Steel pipe length inspection: steel tape measure, manual and automatic length measurement. ④ Steel pipe curvature inspection: Use a ruler, level (1m), feeler gauge, and thin wire to measure the curvature per meter and the curvature of the entire length. ⑤ Inspection of steel pipe end bevel angle and blunt edge: square ruler and clamping plate. 3． Steel pipe surface quality inspection: 100% ① Manual visual inspection: lighting conditions, standards, experience, markings, steel pipe rotation. ② Non-destructive inspection: 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 level. b. Eddy current flaw detection ET: (electromagnetic induction): mainly sensitive to point-shaped (hole-shaped) defects. Standard: GB/T 7735-2004. Level: B level. 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 level 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 testing: fluorescence, coloring, detecting surface defects of steel pipes. 4. Steel management performance inspection: ① Tensile test: measure stress and deformation, and determine the strength (YS, TS) and plasticity index (A, Z) of the material. Longitudinal and transverse specimens, pipe sections, arc-shaped and circular specimens (￠10, ￠12.5). Small diameter thin wall steel pipe, large diameter thick wall steel pipe, fixed gauge length. Note: The elongation of the specimen after fracture is related to the specimen size 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) ③Hardness test: Brinell hardness HB, Rockwell hardness HRC, Vickers hardness HV, etc. ④Hydraulic test: test pressure, pressure stabilization time, p=2Sδ/D 5. Steel pipe process performance inspection process: 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 ② Ring pull test: L=15mm, no cracks, it is qualified ③Expansion and curling test: top-center taper is 30°, 40°, 60° ④Bending test: can replace the flattening test (for large diameter pipes) 6. Metallurgical analysis of steel pipe: ①High-power inspection (microscopic analysis): non-metallic inclusions 100x GB/T 10561 Grain size: grade, grade difference. Organization: M, B, S, T, P, F, A-S. Decarburization layer: inner and outer. Method A rating: Class A – sulfide, Class B – oxide, Class C – silicate, D – spherical oxidation, Class DS. ②Low magnification test (macroscopic analysis): naked eye, magnifying glass 10x or less. a. Acid etching test method. b. Sulfur print inspection method (tube blank inspection, showing low-cultured structures and defects, such as looseness, segregation, subcutaneous bubbles, skin folds, white spots, inclusions, etc. c. Tower-shaped hairline inspection method: inspection of the number of hairlines, Length, and distribution. Post time: Feb-01-2024