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Inspections of Seamless Steel Pipes
Jun 11, 2021
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Under normal circumstances, seamless steel pipes need to be tested for the relevant quality. There are many methods of quality standards of seamless steel pipes. Then, what are the common ones? Let's see them in this article.
Inspections of seamless steel pipes
1. Check the size and shape of steel pipes
(1) Inspections of wall thicknesses of steel pipes: micrometers, ultrasonic thickness measuring instrument
(2) Check the outer diameter and ellipticity of the steel pipe: calipers, vernier calipers, ring gauges
(3) Inspections of steel pipes lengths: steel tapes, manual, automatic length measurement
(4) Inspections of the bending of steel pipes: straight rulers, level rulers (1m), feelers, thin line measurement of bending per meters, full length of bending
(5) Inspections of the steel pipe's end face groove angles and blunt edges: angle squares, clamping plates
2. The quality inspection of the steel tube surface should reach 100%.
(1) Artificial visual inspections: lighting conditions, standards, experience, marks, steel pipe rotation
(2) Non-destructive inspections:
A. UT (ultrasonic flaw detection): The uniform material surfaces of all kinds of materials and internal crack defects are more sensitive.
B. ET (Eddy current detections) (electromagnetic induction): It is mainly sensitive to hole shaped defects.
C. MT (Magnetic powder) and magnetic leakage inspections: magnetic inspections. They are suitable for the detection of surface and near surface defects of ferromagnetic materials.
D. Electromagnetic ultrasonic flaw detections: no coupling medium is needed. It can be applied to high temperature, high speed, rough steel pipe surface flaw detection.
E. Penetration flaw detection: fluorescence, coloring, detection of steel surface defects
3. Chemical composition analysis: chemical analysis, instrumental 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 spectrometers: C, Si, Mn, P, S, Cr, Mo, Ni, CN, A1, W, V, Ti, B, Nb, As, S N, Sb, Pb, Bi in the block samples
(3) N-0 instrument: gas content analysis N, O
4. Physical and chemical properties inspection of steel pipes:
(1) Tensile tests: test stress and deformation, determine the strength of the material (YS, TS) and plastic index (A, Z) longitudinal, transverse sample sections, arc types, round samples (￠10, ￠12.5) small diameters, large diameters, thick wall calibration distances
Note: The elongation of the specimen after fracture is related to the size of the specimen GB /T 1760.
(2) Impact tests: CVN, notch C type, V type, J value J/cm2, standard sample 10×10×55(mm) non-standard sample 5×10×55(mm)
(3) Hardness tests: Brinell hardness HB, Rockwell hardness HRC, Vickers hardness HV, etc.
(4) Hydraulic tests: the test pressure, the stabilizing time, P =2Sδ/D
5. Inspections of steel pipes' process performances:
(1) Flatening tests: round samples, C shaped sample (S/ D>0.15) = (1 + 2) S/H (+ ∝ S/D) L = 40 ~ 100, per unit length deformation coefficient= 0.07 ~ 0.08 mm
(2) Ring pull tests: L=15mm (no crack is qualified.)
(3) Flared and flanged tests: top taper is 30°, 40° and 60°.
(4) Bending tests: it can replace flattening tests (for large-caliber pipes).
6. The metallographic analysis of seamless steel pipes:
(1) High power tests (microscopic analysis) non-metallic inclusions 100X GB/T 10561 grain size: grade, grade structures: M, B, S, T, P, F, A-S
decarbonization layer: inside and outside A rating: A class - sulfides B class - oxides C class - silicates D- spherical oxides DS class
(2) Low power tests (macro analysis): Naked eye, magnifying glass 10X below
A. Acid etching tests.
B. Sulfur imprint tests (tube billet tests can show low growth tissue and defects, such as porosity, segregation, subcutaneous bubbles, skin turning, white spots, inclusions, etc.)
C. Tower hairline tests: check the number, length and distribution of hairlines.
The above are the common main methods and the process of seamless steel pipes inspections just for your reference.
Inspections of seamless steel pipes
1. Check the size and shape of steel pipes
(1) Inspections of wall thicknesses of steel pipes: micrometers, ultrasonic thickness measuring instrument
(2) Check the outer diameter and ellipticity of the steel pipe: calipers, vernier calipers, ring gauges
(3) Inspections of steel pipes lengths: steel tapes, manual, automatic length measurement
(4) Inspections of the bending of steel pipes: straight rulers, level rulers (1m), feelers, thin line measurement of bending per meters, full length of bending
(5) Inspections of the steel pipe's end face groove angles and blunt edges: angle squares, clamping plates
2. The quality inspection of the steel tube surface should reach 100%.
(1) Artificial visual inspections: lighting conditions, standards, experience, marks, steel pipe rotation
(2) Non-destructive inspections:
A. UT (ultrasonic flaw detection): The uniform material surfaces of all kinds of materials and internal crack defects are more sensitive.
B. ET (Eddy current detections) (electromagnetic induction): It is mainly sensitive to hole shaped defects.
C. MT (Magnetic powder) and magnetic leakage inspections: magnetic inspections. They are suitable for the detection of surface and near surface defects of ferromagnetic materials.
D. Electromagnetic ultrasonic flaw detections: no coupling medium is needed. It can be applied to high temperature, high speed, rough steel pipe surface flaw detection.
E. Penetration flaw detection: fluorescence, coloring, detection of steel surface defects
3. Chemical composition analysis: chemical analysis, instrumental 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 spectrometers: C, Si, Mn, P, S, Cr, Mo, Ni, CN, A1, W, V, Ti, B, Nb, As, S N, Sb, Pb, Bi in the block samples
(3) N-0 instrument: gas content analysis N, O
4. Physical and chemical properties inspection of steel pipes:
(1) Tensile tests: test stress and deformation, determine the strength of the material (YS, TS) and plastic index (A, Z) longitudinal, transverse sample sections, arc types, round samples (￠10, ￠12.5) small diameters, large diameters, thick wall calibration distances
Note: The elongation of the specimen after fracture is related to the size of the specimen GB /T 1760.
(2) Impact tests: CVN, notch C type, V type, J value J/cm2, standard sample 10×10×55(mm) non-standard sample 5×10×55(mm)
(3) Hardness tests: Brinell hardness HB, Rockwell hardness HRC, Vickers hardness HV, etc.
(4) Hydraulic tests: the test pressure, the stabilizing time, P =2Sδ/D
5. Inspections of steel pipes' process performances:
(1) Flatening tests: round samples, C shaped sample (S/ D>0.15) = (1 + 2) S/H (+ ∝ S/D) L = 40 ~ 100, per unit length deformation coefficient= 0.07 ~ 0.08 mm
(2) Ring pull tests: L=15mm (no crack is qualified.)
(3) Flared and flanged tests: top taper is 30°, 40° and 60°.
(4) Bending tests: it can replace flattening tests (for large-caliber pipes).
6. The metallographic analysis of seamless steel pipes:
(1) High power tests (microscopic analysis) non-metallic inclusions 100X GB/T 10561 grain size: grade, grade structures: M, B, S, T, P, F, A-S
decarbonization layer: inside and outside A rating: A class - sulfides B class - oxides C class - silicates D- spherical oxides DS class
(2) Low power tests (macro analysis): Naked eye, magnifying glass 10X below
A. Acid etching tests.
B. Sulfur imprint tests (tube billet tests can show low growth tissue and defects, such as porosity, segregation, subcutaneous bubbles, skin turning, white spots, inclusions, etc.)
C. Tower hairline tests: check the number, length and distribution of hairlines.
The above are the common main methods and the process of seamless steel pipes inspections just for your reference.
