16. What tests do high-frequency welded steel pipes need to do?

16.1. Chemical Composition Analysis
The chemical composition of high-frequency welded steel pipes has an important impact on their performance, so chemical composition analysis is required. This is usually carried out by chemical analysis or instrumental analysis, such as infrared C-S instrument, direct reading spectrometer, etc., which is used to analyze the content of C, S, Si, Mn, P, Cr, Mo, Ni and other elements in steel pipes.
16.2. Geometric dimensions and shape inspection
Wall Thickness Inspection: Use tools such as micrometers and thickness gauges to measure the wall thickness of steel pipes to ensure they are within the specified tolerances.
Outer diameter and ovality inspection: Measure the outer diameter and ovality of steel pipes through tools such as snap gauges, vernier calipers, and ring gauges to evaluate their geometric dimensional accuracy.
Length inspection: Use tools such as steel tape measures to measure the length of the steel pipe to ensure that it meets the requirements of fixed or double rulers.
Bend inspection: Use tools such as rulers, levelers, and feeler gauges to measure the bending degree per meter and the full length of the steel pipe to ensure its straightness.
End face bevel angle and blunt edge inspection: Use tools such as angle rulers and pallets to check the bevel angle and blunt edge size of the steel pipe end face to ensure it meets welding requirements.
16.3. Physical Properties Test
Mechanical property test: including flattening test, flare test, bending test and hardness test, etc., used to evaluate the tensile strength, yield strength, elongation and other mechanical properties of steel pipes.
Water or air pressure test: Conduct a water or air pressure test on the steel pipe to check its air tightness and weld strength. This is an important step to ensure that the steel pipe can withstand a certain internal pressure during use.
16.4. Non-destructive inspection
Ultrasonic inspection: Ultrasonic inspection of the inner and outer welds of steel pipes and the base metal on both sides of the weld seam to find possible defects, such as cracks, slag inclusions, etc.
X-ray inspection: X-ray industrial television inspection is carried out on the inner and outer welds of steel pipes, and the image processing system is used to ensure the sensitivity of flaw detection and further confirm the quality of the weld.
Eddy current testing: In some cases, eddy current testing methods are allowed to be used instead of hydrostatic testing to detect defects on the surface and near surface of steel pipes.
16.5. Other tests
Expansion test: The diameter expansion test is carried out on the submerged arc welded straight seam steel pipe to improve the dimensional accuracy of the steel pipe and improve the distribution of internal stress of the steel pipe.
Pipe end magnetic particle inspection: Conduct magnetic particle inspection on the pipe end of the steel pipe to find possible cracks and other defects.