Seamless steel pipes are divided into two categories: hot-rolled and cold-rolled (dial) seamless steel pipes. Hot-rolled seamless steel pipes are divided into general steel pipes, low and medium pressure boiler steel pipes, high pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, petroleum cracking pipes, and geological steel pipes. and other steel pipes, etc.

In addition to general steel pipes, low and medium pressure boiler steel pipes, high pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, petroleum cracking pipes, and other steel pipes, cold-rolled (pulled) seamless steel pipes also include carbon thin-walled steel pipes, alloy thin-walled steel pipes, Stainless thin-walled steel pipe, special-shaped steel pipe. The outer diameter of hot-rolled seamless pipes is generally greater than 32 mm, and the wall thickness is 2.5-75 mm. The diameter of cold-rolled seamless pipes can reach 6 mm and the wall thickness can reach 0.25 mm. The outer diameter of thin-walled pipes can reach 5 mm and the wall thickness is less than 0.25 mm. , cold rolling has higher dimensional accuracy than hot rolling.

General use seamless steel pipe: It is made of high-quality carbon steel such as 10, 20, 30, 35, 45, 16Mn, 5MnV, etc. Cold rolled. Seamless pipes made of low carbon steel such as 10 and 20 are mainly used for fluid transportation pipelines. 45, 40Cr and other medium carbon steel seamless pipes are used to manufacture mechanical parts, such as the stressed parts of automobiles and tractors. Generally, seamless steel pipes are used to ensure the strength and flattening test. Hot-rolled steel pipes are delivered in hot-rolled or heat-treated state; cold-rolled steel pipes are delivered in heat-treated state.

Seamless steel pipes for low and medium pressure boilers: used to manufacture various low and medium pressure boilers, superheated steam pipes, boiling water pipes, water wall pipes and superheated steam pipes, large smoke pipes, small smoke pipes and arch brick pipes for locomotive boilers; Hot-rolled or cold-rolled (dial) seamless steel pipes with high-quality carbon structural steel. Mainly made of No. 10 and 20 steel, in addition to ensuring chemical composition and mechanical properties, hydraulic tests, hemming, flaring, flattening and other tests are required. Hot rolling is delivered in hot rolling state, and cold rolling (dialing) is delivered in heat treatment state.

High-pressure boiler steel pipe: mainly used to manufacture high-quality carbon structural steel, alloy structural steel and stainless heat-resistant seamless steel pipe for steam boiler pipes with high pressure and above. These boiler pipes often work under high temperature and high pressure, The pipe will also undergo oxidation and corrosion under the action of high temperature flue gas and water vapor, so the steel pipe is required to have high lasting strength, high oxidation resistance, and good organizational stability.

Seamless steel pipes for geological drilling and oil drilling: In order to find out the underground rock structure, groundwater, oil, natural gas and mineral resources, drilling rigs are used to drill wells. Oil and natural gas exploitation is more inseparable from drilling wells. Seamless steel pipes for oil drilling for geological drilling are the main equipment for drilling, mainly including core outer pipe, core inner pipe, casing, drill pipe and so on. Because the drilling pipe needs to work deep into the formation depth of several kilometers, the working conditions are extremely complex, the drill pipe is subjected to stress such as tension, compression, bending, torsion and unbalanced impact loads, and it is also subjected to mud and rock wear. Therefore, the pipe material is required to be Must have sufficient strength, hardness, wear resistance and impact toughness.

Petroleum cracking tubes: seamless tubes for furnace tubes, heat exchanger tubes and pipes used in petroleum refineries. In addition to the certified chemical composition and various mechanical properties, the steel pipe must also ensure water pressure, flattening, flaring and other tests, as well as surface quality and non-destructive testing. Steel pipes are delivered in heat-treated condition. In addition to ensuring the chemical composition and mechanical properties, all steel pipes used to withstand fluid pressure must ensure that the hydrostatic test is qualified.