Acceptance of seamless steel pipes-Boiler Tubes,Heat-Exchanger Tubes,Superheater Tubes,Supplier,Beite

Acceptance of seamless steel pipes

Acceptance standards and quality inspection methods for seamless steel pipes

1. Chemical composition analysis:

Chemical analysis, instrumental analysis (infrared C-S instrument, direct reading spectrometer, zcP, etc.).

①Infrared C-S instrument: analyzes C and S elements in iron alloys, steel-making raw materials, and 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 the bulk sample

③N-0 instrument: gas content analysis N, O.

2. Inspection of geometric dimensions and shape of steel pipes:

①Check the wall thickness 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.

③ Steel tube length check: steel tape measure, manual and automatic length measurement.

④Bending inspection of steel pipes: straight ruler, horizontal ruler (1m), feeler ruler, thin line to measure the bending degree per meter, full length bending degree.

⑤Check the angle and blunt edge of the end face of the steel pipe: square ruler, card board.

3. Steel pipe surface quality inspection: 100%

①Artificial 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 particle 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: Level C4

d. Electromagnetic ultrasonic flaw detection:

No coupling medium is required, it can be applied to high temperature and high speed, rough steel tube surface flaw detection.

e. Penetration testing:

Fluorescence, coloring, detection of steel tube surface defects.

4. Steel management performance inspection:

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

Longitudinal and transverse sample tube sections, arc-shaped and round samples (￠10, ￠12.5)

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 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 stabilizing time, p=2Sδ/D

5. Steel pipe process performance inspection:

① Flattening test: round sample C-shaped sample (S/D>0.15) H=(1+2)S/(∝+S/D)

L=40～100mm (provided by http://www.tjdwfgz.com) Deformation coefficient per unit length=0.07～0.08

② Ring tensile test: L=15mm No 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)

6. Metallurgical analysis of seamless steel tubes:

①High 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

Method A Rating: Class A-Sulfide Class B-Oxide Class C-Silicate D-Spherical Oxidation DS Class

②Low magnification test (macro analysis): naked eye, magnifying glass less than 10x

a. Acid etching test method, b. Sulfur print test method (tube blank test, showing low-cultured tissue and defects, such as looseness, segregation, subcutaneous bubbles, skin peeling, white spots, inclusions, etc.

c. Tower-shaped hairline inspection method: inspect the number, length and distribution of hairline.