Spiral steel pipe is a spiral seam steel pipe, which is made of strip coil plate as raw material, often formed by warm extrusion, and welded by automatic double-wire and double-side submerged arc welding process. Adopting advanced double-sided submerged arc welding technology, the welding can be achieved in the best position, not easy to appear the wrong edge, welding deviation and penetration defects, easy to control the welding quality.