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

Generally speaking, the diameter of spiral steel pipe can be divided into outer diameter, inner diameter, and nominal diameter. The outer diameter of a spiral steel pipe is indicated by the letter D, followed by the size and wall thickness of the outer diameter. For example, a seamless steel pipe wi