What are the specific contents of seamless steel pipe acceptance?
Inspection of geometric dimensions and shape of steel pipes:
①Wall thickness inspection of steel pipe: micrometer, ultrasonic thickness gauge, no less than 8 points on both ends and record.
②Check the outer diameter and ellipticity of the steel pipe: caliper, vernier caliper, ring gauge, measure the maximum point and minimum point.
③Check the length of steel pipe: steel tape measure, manual and automatic length measurement.
④Bending inspection of steel pipe: straight ruler, horizontal ruler (1m), ruler and thin line measure the bending degree of every meter and the bending degree of yin.
⑤Check the angle and blunt edge of the end face of the steel pipe: square ruler, card board.
Steel pipe surface quality inspection:
①Manual visual inspection: lighting conditions, standards, experience, logo, steel pipe rotation.
②Nondestructive inspection:
a. Ultrasonic flaw detection UT:
It is sensitive to cracks on the surface and internal cracks of materials with uniform materials.
Standard: GB/T 5777-1996 level: C5 level
b. Eddy current testing ET: (Electromagnetic induction)
Mainly sensitive to point-shaped (hole-shaped) defects. Standard: GB/T 7735-2004
Level: Level B
c. Magnetic powder MT and magnetic flux leakage 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 level
d. Electromagnetic ultrasonic flaw detection:
No coupling medium is required, and it can be applied to high-temperature, high-speed, rough steel tube surface inspection.
e. Penetration testing:
Fluorescence, coloring, detection of steel tube surface defects.
Steel management performance inspection:
①Tensile test: measure stress and deformation, determine the strength (YS, TS) and plasticity index (A, Z) of the material
Longitudinal, horizontal sample tube section, arc type, round sample (410, 412.5)
Small caliber, thin wall large caliber, thick wall calibration distance.
Note: The elongation of the sample after breaking is related to the sample size GB/T 1760
②Impact test: CVN, notch C type, V type, work J value/cm2
Standard sample 10x10x55 (mm) Non-standard sample 5x10x55 (mm)
③Hardness test: Brinell hardness HB, Rockwell hardness HRC, Vickers hardness HV, etc.
④Hydraulic test: test pressure, pressure stabilizing time, p=2Sδ/D
Steel pipe process performance inspection:
① Flattening test: round sample C-shaped sample (S/D>0.15) H = (1+2)S/(x+S/D)
L=40~100mm unit length deformation coefficient=0.07~0.08
② Ring tensile test: L=15mm without crack is qualified
③ Flaring and curling test: the top taper is 30°, 40°, 60°
④Bending test: can replace flattening test (for large-diameter pipes)
