Spiral steel pipes should be subjected to mechanical performance test, flattening test and flaring test before leaving the factory, and must meet the requirements of the standard. The quality inspection methods of straight seam steel pipes are as follows:1. Judging from the surface, that is, in appe

Spiral steel pipe is a spiral seam steel pipe made of strip steel coils as raw material, often warm-extruded under urban pressure, spirally bent and formed by automatic double-wire double-sided submerged arc welding process for inner seam and outer seam welding. The raw materials are strip steel coi