Differences between straight seam welded steel pipe and spiral welded steel pipe

First, the metallurgical properties of manufacturing materials

The raw material for spiral welded steel pipe is hot-rolled coil, and straight seam welded steel pipe is made of steel plate socket. The weight of the alloy contained in the coil 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 has a certain helix angle, but the dry plate of the straight seam welded steel pipe is rolled in a direction perpendicular to the axis of the steel plate, so in comparison, the spiral welded steel pipe has better crack resistance.

Second, strength characteristics

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

Third, the welding process comparison

In terms of the welding process, the welding of the two is close to the same. However, in the case of straight seam welded steel pipe, a T-shaped weld may appear during welding, which is a major welding defect. The T-shaped weld is also more likely to crack in the straight seam welded steel pipe. In this regard, due to the different welding directions, the spiral welded steel pipe can well avoid the occurrence of this situation.

Fourth, on-site weldability

The material and port matching size tolerance of the steel pipe determines the on-site weldability. The spiral welded steel pipe is completed in a stable and continuous process under the same working conditions in production, but the straight seam welded steel pipe is different. Its production is carried out in sections. This is also a big difference between the two. The welds of the spiral welded steel pipe are evenly distributed and the pipe shape of the welded steel pipe is also very regular, so it is very good for the on-site weldability of the welding assembly accuracy compared with the straight seam welded steel pipe.