Technical requirements and quality inspection of straight seam pipes

Technical requirements and quality inspection of straight seam pipe According to the standard of GB3092 "welded steel pipe for low pressure fluid transportation", the nominal diameter of welded pipe is 6~150mm, the nominal wall thickness is 2.0~6.0mm, and the length of welded pipe is usually 4~10m. It can be factory-made according to the length of fixed length or multiple length. The surface quality of steel pipe should be smooth, and there are no defects such as folding, cracking, delamination and lap welding.


        The surface of the steel pipe is allowed to have slight defects such as scribes, scratches, misalignment of welds, burns and crusting that do not exceed the negative deviation of the wall thickness, allowing the thickness of the weld to be thickened and the internal weld bead to exist. The welded steel pipe should be mechanical. Performance test and flattening test and flaring test, and to meet the requirements of the standard, the steel pipe should be able to withstand a certain internal pressure, if necessary, carry out a pressure test of 2.5Mpa, keep no leakage for one minute, and allow the use of eddy current testing instead. Hydraulic pressure test, eddy current testing is carried out according to GB7735 "Steel Tube Eddy Current Testing Method".


        The eddy current testing method is to fix the probe on the frame, and the flaw detection and the weld seam are kept at a distance of 3~5mm. The weld is fully scanned by the rapid movement of the steel pipe, and the flaw detection signal is automatically processed and automatically sorted by the eddy current flaw detector. To achieve the purpose of flaw detection, the welded pipe after the flaw detection is cut with the flying saw according to the specified length. After the inverted frame is taken off the wire, the ends of the steel pipe should be chamfered at the ends, and the marks are printed. The finished pipe is wrapped in a hexagonal package and then shipped.