According to the production method, the seamless steel pipe can be divided into hot rolled seamless steel pipe, cold rolled seamless steel pipe, cold drawn seamless steel pipe, extrusion seamless steel pipe, pipe jacking and so on. According to the section shape, the seamless steel pipe is divided into round and irregular two kinds, irregular pipe has square, oval, triangle, hexagonal, melon seed shape, star shape, with a variety of complex shapes. The maximum diameter is 900mm and the minimum diameter is 4mm. According to different uses, there are thick wall seamless steel pipe and thin wall seamless steel pipe. 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.A seamless steel pipe 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 of which have their own technological regulations.The materials are ordinary and high quality carbon structural steel (Q215-A ~ Q275-A and No. 10 ~ 50 steel), low alloy steel (09MnV, 16Mn, etc.), alloy steel, stainless acid resistant steel, etc.According to the purpose, it is divided into general purpose (for water and gas pipelines and structural parts, mechanical parts) and special purpose (for boiler, geological exploration, bearing, acid resistance, etc.).Seamless steel pipe has a wide range of uses.1. The general purpose seamless steel pipe is rolled by ordinary carbon structural steel, low alloy structural steel or alloy structural steel, the maximum output, mainly used for conveying fluid pipeline or structural parts.2. According to the use of different supplies into three categories:A. Supply according to chemical composition and mechanical properties.b. Supply according to mechanical properties.c. Supply according to hydraulic test. Steel tubes supplied according to class a and Class b, if used to withstand liquid pressure, shall also be subjected to hydrostatic tests.3. The special purpose of seamless pipe with boiler seamless pipe, chemical power, geological seamless steel pipe and petroleum seamless pipe and so on.Seamless steel pipe has hollow section, widely used for conveying fluid pipeline, such as conveying oil, natural gas, gas, water and some solid materials, etc. Compared with solid steel such as round steel, steel pipe is a kind of economic section steel because of its light weight and the same bending and torsional strength.It is widely used in the manufacture of structural parts and mechanical parts, such as oil drill pipe, automobile transmission shaft, bicycle frame and steel scaffolding used in construction. It can improve the utilization rate of materials, simplify the manufacturing process, save materials and processing hours, and has been widely used in the manufacture of steel pipe.