Spiral welded pipe: It is made by rolling low-carbon carbon structural steel or low-alloy structural steel strip into a pipe blank at a certain angle of the spiral line (called the forming angle), and then welding the pipe seam together. It can produce large-diameter steel pipes with narrower strip steel. The specifications are expressed as outer diameter * wall thickness, and the welded pipe should ensure that the hydrostatic test, tensile strength, and cold bending performance of the weld meet the requirements.