Comparison of ERW steel pipe and SSAW steel pipe

Compared with SSAW, there is little difference in price between ERW steel pipe and SSAW steel pipe. The length of  SSAW weld joint is about 2~3 times  of ERW weld joint, and its internal weld tumor has no technical ability to remove, so it is inevitable to increase the friction resistance of the inner wall of the pipeline when conveying medium. The length of ERW weld joint is short, and the internal welding tumor can be removed. When the medium flows in the pipe, the friction generated by the inner wall of the pipe is smaller than that of the SSAW steel pipe.

According to the results of residual stress measurement, the ERW welded pipe circumferential forming internal stress is small, which is beneficial to the pipe. For SSAW pipe, due to its large weld area, the stress inside the weld is both tensile and compressive, and the stress state is more complex than that of ERW pipe, which is related to the forming process of spiral welded pipe. The tensile stress in a wide range of SSAW steel pipes in the weld and the inner wall of the heat affected zone will have adverse effects on the crack initiation and stress corrosion of the inner wall defects .ERW steel pipe has short weld joint (compared with spiral seam steel pipe), uniform wall thickness, stable length, high geometric precision, corrosion resistance and easy to ensure the quality of assembly and welding. At the same time, because the engineering temperament contains a small amount of water and carbon dioxide, with weak acidity, it is not suitable to use SSAW steel pipe.