The technical requirements and inspection of straight seam welded pipes are based on the GB3092 "Welded Steel Pipes for Low-Pressure Fluid Transport" standard. The nominal diameter of the welded pipe is 6~150mm, the nominal wall thickness is 2.0~6.0mm, and the length of the welded pipe is usually 4~10 meters. It can be shipped from the factory in fixed length or multiple lengths. The surface of the steel pipe should be smooth, and defects such as folding, cracks, delamination, and lap welding are not allowed. The surface of the steel pipe is allowed to have minor defects such as scratches, scratches, weld dislocations, burns and scars that do not exceed the negative deviation of the wall thickness. Thickening of the wall thickness at the weld and the presence of internal weld bars are allowed.
Welded steel pipes should undergo mechanical performance tests, flattening tests and expansion tests, and must meet the requirements stipulated in the standard. The steel pipe should be able to withstand the internal pressure of 2.5Mpa and maintain no leakage for one minute. It is allowed to use eddy current flaw detection method instead of hydrostatic test. Eddy current flaw detection is carried out in accordance with the standard GB7735 "Eddy Current Flaw Detection Inspection Method for Steel Pipes". The eddy current flaw detection method is to fix the probe on the frame, keep a distance of 3~5mm between the flaw detection and the weld, and rely on the rapid movement of the steel pipe to conduct a comprehensive scan of the weld. The flaw detection signal is automatically processed and automatically sorted by the eddy current flaw detector. To achieve the purpose of flaw detection. After flaw detection, the welded pipe is cut to the specified length with a flying saw, and is rolled off the production line via a flip frame. Both ends of the steel pipe should be flat-chamfered and marked, and the finished pipes should be packed in hexagonal bundles before leaving the factory.
