The difference between straight seam welded steel pipe and spiral welded steel pipe

Metallurgical properties of the production materials: The raw materials for producing spiral welded steel pipes are hot-rolled coils, and the straight seam welded steel pipes are made of steel plates. The weight of the alloy contained in the coiled plate is less than that of the steel plate. It is for this reason that the spiral welded steel pipe has higher weldability than the steel plate, in addition. The rolling direction of the coil plate has a certain helix angle, but the dry plate of the straight seam welded steel pipe is rolled in the direction perpendicular to the axis of the steel plate, so in comparison, the spiral welded steel pipe has better crack resistance.

Strength characteristics: The rotation angle of the spiral welded steel pipe weld is between 50-75 degrees, so the stress at the weld joint is 60-85% of that of the straight seam welded steel pipe. Therefore, if the two are under the same working pressure, the pipe wall of the two welded pipes with the same diameter and the spiral welded steel pipe can be reduced. Therefore, if the spiral welded steel pipe explodes, its blast hole will not appear in the weld, and its safety is higher than that of the straight seam welded steel pipe.

Welding process comparison: In terms of the welding process, the welding of the two is close to the same. However, for straight seam welded steel pipes, T-shaped welds may appear during welding, a major welding defect. Straight seam welded steel pipes with T-shaped welds are also more likely to produce cracks. At this point, due to the different welding directions, spiral welded steel pipes can avoid this situation.

Field weldability: The material of the steel pipe and the port fit size tolerance determine the field weldability. Spiral welded steel pipes are produced in a stable and continuous process under the same working conditions, but straight seam welded steel pipes are different in that their production is carried out in sections. This is also a big difference between the two. The welds of spiral welded steel pipes are evenly distributed and the pipe shape of the welded pipes is also very regular, so along with the straight seam welded steel pipes, it ensures the welding assembly accuracy of on-site weldability.