Weld angle of spiral steel pipe

　　Spiral steel pipe is a kind of spiral seam steel pipe, which is welded by automatic double wire double-sided submerged arc welding process and is often extruded by warm extrusion.

　　The helical angle of spiral steel pipe weld is generally 50-75 degrees, so the synthetic stress of spiral weld is 60-85% of the main stress of straight welded pipe. Under the same working pressure, the thickness of the spiral steel pipe with the same diameter can be reduced than that of the longitudinal welded pipe.

　　1. When the spiral steel pipe is blasted, because the normal stress and synthetic stress of the weld are relatively small, the blasting hole generally does not originate from the spiral weld, and its safety is higher than that of the straight spiral steel pipe.

　　2. When there is a parallel defect near the 3PE Sch 120 Carbon Welded Spiral Steel Pipe, the danger of expansion of the spiral weld is not as great as that of the straight weld because the stress of the spiral weld is small.

　　3. Because the radial stress is the maximum stress on the steel pipe, the weld will bear the maximum load when it is in the direction of vertical stress. That is, the load that the longitudinal joint bears is the largest, and the load of the circumferential weld is the smallest, and the spiral seam is between the two.