Spiral welded pipe is a low carbon carbon structural steel or low alloy structural steel steel strip according to a certain angle of the helix (called the molding angle) rolled into a billet, and then welded the pipe seam made of it can be a narrower strip to produce a large diameter steel pipe. Its specifications are expressed in terms of outer diameter * wall thickness, welded pipe should ensure that the hydrostatic test, the tensile strength of the weld and the cold bending properties should be in accordance with the provisions.