The seamless steel pipe is made by perforating the whole round steel, and the steel pipe without weld seam on the surface is called seamless steel pipe. According to the production method, seamless steel pipes can be divided into hot-rolled seamless steel pipes, cold-rolled seamless steel pipes, cold-drawn seamless steel pipes, extruded seamless steel pipes, and pipe jacking. According to the cross-sectional shape, seamless steel tubes are divided into two types: round and special-shaped, and special-shaped tubes have various complex shapes such as square, oval, triangular, hexagonal, melon-shaped, star-shaped, and finned tubes. The maximum diameter is up to 900mm and the minimum diameter is 4mm. According to different uses, there are thick-walled seamless steel pipes and thin-walled seamless steel pipes. Seamless steel pipes are mainly used as petroleum geological drilling pipes, cracking pipes for petrochemical industry, boiler pipes, bearing pipes, and high-precision structural steel pipes for automobiles, tractors, and aviation.

A steel pipe that is seamless along the perimeter of its cross-section. According to different production methods, it is divided into hot-rolled pipe, cold-rolled pipe, cold-drawn pipe, extruded pipe, pipe jacking, etc., all of which have their own process regulations.

Materials include ordinary and high-quality carbon structural steel, low alloy steel, alloy steel, etc.

According to the purpose, it is divided into two categories: general purpose (for water, gas pipelines and structural parts, mechanical parts) and special purpose (for boilers, geological exploration, bearings, acid resistance, etc.).

The outer diameter of hot-rolled seamless pipe is generally greater than 32mm, and the wall thickness is 2.5-200mm. The outer diameter of cold-rolled seamless steel pipe can reach 6mm, and the wall thickness can reach 0.25mm. Rolling has higher dimensional accuracy than hot rolling. Generally, seamless steel pipes are made of 10, 20, etc., alloy structural steels P5, P9, P11, P22, P91, P92, 15mog, 20mog, 12crmog, 15crmog, 12cr2mog, 12crmovg, etc. of. 10, 20 and other low carbon steel seamless pipes are mainly used for fluid conveying pipelines. Generally, seamless steel pipes are used to ensure strength and flattening tests. Hot-rolled steel pipes are delivered in a hot-rolled or heat-treated state; cold-rolled steel pipes are delivered in a heat-treated state.