Spiral welded pipe: It is made by rolling a low carbon carbon structural steel or a low alloy structural steel strip into a tube blank at a certain angle of a helix (called a forming angle), and then welding the pipe seam, which can be used in a narrower manner. Strip steel for the production of large diameter steel pipes. The welded pipe shall ensure that the hydraulic test and the tensile strength and cold bending performance of the weld are in compliance with the regulations.