Seamless steel pipes are made of monolithic metal with no joints on the surface. According to sectional shape, seamless steel pipes are circular and irregular. Irregular pipe has square, oval, triangular, hexagonal, melon seed, star, with a variety of complex shape finned pipe.
The maximum diameter of seamless steel pipe is 650mm, and the minimum diameter is 0.3mm. According to different uses, there are extra-heavy pipes and thin walled pipes.
Seamless steel pipe is mainly used for petroleum geological drilling pipe, Petrochemical cracking pipe, boiler pipe, bearing pipe and automobile, tractor, aviation high-precision structural steel pipe.
Seamless steel pipes are divided into hot-rolled pipes, cold-rolled pipes, cold-drawn pipes, extruded pipes and pipe jacking according to different production methods, and each has its own process stipulation. The materials include ordinary and high quality carbon structural steels (Q215-A-Q275-A and No. 10-50), low alloy steels (09MnV, 16Mn, etc.), alloy steels, stainless steel and acid-resistant steels.
According to the use of seamless steel pipe, it can be divided into two types: general use (for water conveyance, gas pipeline and structure, mechanical parts) and special use (for boiler, geological exploration, bearing, acid resistance, etc.).