Quality inspection method of Seamless pipe

1. Chemical composition analysis: chemical analysis, instrument analysis (infrared C-S instrument, direct reading spectrometer, zcP, etc.).

① Infrared C-S instrument: analysis of ferroalloy, 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 and Bi in bulk samples

③ N-0 meter: gas content analysis N, O

2. Check the geometric size and shape of steel pipe:

(1) Steel pipe wall thickness inspection: micrometer, ultrasonic thickness measuring instrument, both ends of no less than 8 points and record.

(2) Steel pipe outer diameter, ellipticity inspection: caliper, vernier caliper, ring gauge, measured points, small points.

③ Steel pipe length inspection: steel tape, manual, automatic length measurement.

④ Check the bending degree of the steel pipe: straight ruler, level (1m), feeler ruler, fine line to measure the bending degree per meter, full-length bending degree.

(5) Steel pipe end bevel Angle and blunt edge inspection: Angle square, clamp plate.

3. Steel pipe surface quality inspection:

① Artificial naked eye inspection: lighting conditions, standards, experience, marking, steel tube rotation.

② Nondestructive testing:

a. Ultrasonic flaw detection UT:

It is sensitive to the surface and internal cracks of all kinds of uniform materials.

b. Eddy current detection ET: (electromagnetic induction)

It is mainly sensitive to punctate (cavity shaped) defects.

Level: B

c. Magnetic particle MT and magnetic leakage testing:

Magnetic flaw detection is suitable for surface and near-surface defect detection of ferromagnetic materials.

d. Electromagnetic ultrasonic flaw detection:

Without coupling medium, it can be applied to high temperature, high speed, rough and dry steel pipe surface flaw detection.

e. Penetration detection:

Fluorescence, coloring, detection of steel pipe surface defects.

4. Physical and chemical properties of steel tubes:

① Tensile test: measure stress and deformation, determine the strength of the material (YS, TS) and plastic index (A, Z)

Longitudinal, transverse sample tube section, arc type, round sample (￠10, ￠12.5)

Small diameter, thin wall, large diameter, thick wall calibration distance.

Note: The elongation of the sample after breaking is related to the sample size GB/T 1760

② Impact test: CVN, notch C type, V type, power 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, stable pressure time, p=2Sδ/D

5. Process performance inspection of steel pipe:

① Flattening test: round specimen C shape specimen (S/D>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 without crack is qualified

(3) flaring and flaring test: top taper is 30°, 40°, 60°

(4) Bending test: can replace the flattening test (for large diameter pipe)