(1) Since the length of the SAW weld is approximately 4-5 times the length of the ERW weld, the internal welding knob has no process ability to remove it, so the friction of the inner wall of the pipe...
(1) Since the length of the SAW weld is approximately 4-5 times the length of the ERW weld, the internal welding knob has no process ability to remove it, so the friction of the inner wall of the pipeline is inevitably increased when conveying the medium. The ERW welding seam has a short length, and the internal welding knob can be removed. When the medium flows in the pipeline, the friction generated on the inner wall of the pipeline is smaller than that of the spiral seam submerged arc welded steel pipe. It is very advantageous to reduce the temperature rise caused by friction.
(2) According to the results of the residual stress measurement, the internal stress of the ERW welded pipe in the circumferential forming is small, which is beneficial to the pipe. For the SAW welded pipe, due to its large weld area, there are tension and pressure in the weld. The stress state is more complicated than that of the ERW pipe, which is related to the forming process of the spiral welded pipe. The inner surface is elastic and complex tensile stress, the axial stress is + 450Mpa, and the circumferential stress is + 344Mpa. This wide range of tensile stress in the weld and the wall of the heat affected zone will adversely affect the crack initiation and stress corrosion of the inner wall defect Impact.
(3) Since the length of the SAW weld is about 4-5 times the length of the high-frequency straight seam pipe, the anticorrosive treatment of the finished pipe is difficult; the ERW steel pipe has a short weld seam (compared with the spiral seam steel pipe), The thickness of the steel pipe is uniform, the length is stable, the geometric accuracy is high, and the quality of anti-corrosion and assembly and welding is easy to guarantee.