Small-diameter spiral steel pipes can be divided into: small-diameter seamless steel pipes and straight-seam (also called welded) small-diameter steel pipes. According to different production methods, they can be divided into hot-rolled pipes, cold-rolled pipes, cold-drawn pipes, extruded pipes, etc. Small-diameter spiral steel pipes are mainly used in the manufacture of ships, boilers and aircraft, the manufacture of coal-fired boilers, the development of the chemical industry, and the drilling, production, and transportation of oil and natural gas.
The internal pressure endured by the steel pipe is usually the two main forces on the inner wall, namely the radial stress ƀY and the axial stress ƀX. The resulting welding stress ƀ=ƀY (l /4sin2α+cos2α)1/2, where α is the angle of the SSAW steel pipe. The angle of the spiral welded pipe is usually 50-75 degrees, that is, the spiral welded steel pipe produces huge resultant stress. Under the pressure of a constant diameter, within the same workload, the wall thickness of the spiral welded pipe may be reduced a lot.
Features of small diameter spiral steel pipe:
Spiral steel pipe will use material to create larger diameter pipes, or constant-size preforms can be used to produce pipes of completely different diameters. Its production method is simple and clear, but the production efficiency is very high. However, compared with the constant LSAW steel pipe, the weld length increased by half an hour to 100%, and the productivity was low. Therefore, straight fastening is mainly used for smaller diameter steel pipes, and spiral welded pipes are mainly used for large diameter welded pipes.
