The difference between straight seam welded pipe and spiral welded pipe

1. Metallurgical properties of materials

The raw material for the production of spiral welded pipes is hot-rolled coils, and the straight seam welded pipes are made of steel plates. 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 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 pipe is rolled along the direction perpendicular to the axis of the steel plate, so in comparison, the spiral welded pipe has better crack resistance.

2. Strength characteristics

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

3. Welding process comparison

In the welding process, the welding of the two is close to the same. However, for straight seam welded pipes, T-shaped welds may appear during welding, which is a major welding defect, and T-shaped welded pipes are also more likely to crack. At this point, due to the different welding directions, the spiral welded pipe can avoid this situation very well.

4. Field Solderability

The material of the steel pipe and the dimensional tolerance of the end fit determine the field weldability. Spiral welded pipes are produced in a stable and continuous process under the same working conditions, but the straight seam welded pipes are different, and their production is carried out in stages. This is also a big difference between the two. The welds of the spiral welded pipe are evenly distributed and the pipe shape of the welded pipe is also very regular, so it is very good to ensure the welding accuracy of the on-site weldability for the straight seam welded pipe.