Spiral welded pipe is made by rolling low carbon carbon structural steel or low alloy structural steel strip at a certain helical angle (called forming angle) into a tube blank, and then welding the pipe seams.
The advantages of spiral welded pipe:
1. Steel pipes of different diameters can be produced by using strip steel of the same width, especially large diameter steel pipes can be produced from narrow strip steel.
2. Under the same pressure conditions, the stress on the spiral welded seam is smaller than that of the straight seam, which is 75% to 90% of that of the straight seam welded pipe, so it can withstand greater pressure. Compared with the straight seam welded pipe of the same outer diameter, the wall thickness can be reduced by 10% to 25% under the same pressure.
3. The size is accurate, generally the diameter tolerance is not more than 0.12%, the deflection is less than 1/2000, and the ovality is less than 1%. Generally, the sizing and straightening process can be omitted.
4. Spiral welded pipe can be continuously produced, and theoretically it can produce infinitely long steel pipes, with little loss of cutting heads and tails, and can improve the metal utilization rate by 6% to 8%.
5. Compared with the straight seam welded pipe, it is more flexible in operation and convenient for changing and adjusting varieties.
6. The equipment is light in weight and low in initial investment. It can be made into a trailer-type flow unit, and the welded pipe can be produced directly at the construction site where the pipeline is laid.
7. Spiral welded pipe is easy to realize mechanization and automation.
The disadvantage of the spiral welded pipe
Because the coiled strip steel is used as the raw material, there is a certain crescent bend, and the welding point is in the edge area of the strip steel with elasticity, so it is not easy to align the welding torch, which affects the welding quality. To do this, complex seam tracking and quality inspection equipment is set up.