Spiral steel pipe is a spiral seam steel pipe made of strip steel coil as raw material, often warm extruded and welded by automatic double wire double-sided submerged arc welding process. The spiral steel pipe sends the strip steel to the welding pipe unit, and the strip steel is rolled by multiple rolls. The strip steel is gradually rolled up to form a circular tube blank with an open gap. Adjust the reduction of the extrusion roll to control the weld gap at 1~3mm, and make both ends of the weld crater flush .