Steel pipes made from a single piece of metal without seams on the surface are called seamless steel pipes. According to the production method, seamless pipes are divided into hot-rolled pipes, cold-rolled pipes, cold-drawn pipes, extruded pipes, and top pipes. According to the cross-sectional shape, seamless steel pipes are divided into two types: round and special-shaped. Special-shaped pipes have square, elliptical, triangular, hexagonal, melon-shaped, star-shaped, and finned pipes. The maximum diameter is 650mm, and the minimum diameter is 0.3mm. According to different uses, there are thick-walled pipes and thin-walled pipes. Seamless steel pipes are mainly used as petroleum geological drilling pipes, petrochemical cracking pipes, boiler pipes, bearing pipes, and high-precision structural steel pipes for automobiles, tractors, and aviation.

Classification:

A steel pipe with no joints along the perimeter of its cross-section. According to different production methods, it can be divided into hot-rolled pipe, cold-rolled pipe, cold-drawn pipe, extruded pipe, pipe jacking, etc., all have their own process regulations. The materials are ordinary and high-quality carbon structural steel (Q215-A～Q275-A and 10～50 steel), low alloy steel (09MnV, 16Mn, etc.), alloy steel, stainless and acid-resistant steel, etc. According to the purpose, it is divided into two types: general purpose (used for water, gas pipelines and structural parts, mechanical parts) and special purpose (used for boilers, geological prospecting, bearings, acid resistance, etc.).