Classification of seamless steel pipes

Classification of seamless steel pipes: Seamless steel pipes are divided into three categories: hot-rolled, cold-rolled, and cold-drawn 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, geological steel pipes and other steel pipes.
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 seamless steel pipes also include carbon thin-walled steel pipes, alloy thin-walled steel pipes, and stainless steel thin-walled steel pipes. Wall steel pipes, special-shaped steel pipes. The outer diameter of hot-rolled seamless steel pipes is generally greater than 32mm, and the wall thickness is 2.5-75mm. The outer diameter of cold-rolled seamless steel pipes can be up to 6mm, and the wall thickness can be up to 0.25mm. The outer diameter of thin-walled pipes can be up to 5mm, and the wall thickness is less than 0.25mm. Cold rolling has higher dimensional accuracy than hot rolling, while cold drawn seamless steel pipe
General seamless steel pipes: made of 10#, 20#, 30#, 35#, 45# and other high-quality carbon structural steels, 16Mn, 5MnV and other low-alloy structural steels or 40Cr, 30CrMnSi, 45Mn2, 40MnB and other alloy steels, hot rolled or cold Rolled. Seamless pipes made of 10 and 20 grade low carbon steel are mainly used for fluid transportation pipelines. Seamless tubes made of medium carbon steel such as 45# and 40Cr are used to manufacture mechanical parts, such as stressed parts of automobiles and tractors. Generally, seamless steel pipes must 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.
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-cooled wall pipes and superheated steam pipes, large smoke pipes, small smoke pipes and arch brick pipes for locomotive boilers, etc. Hot-rolled or cold-rolled (dialed) seamless steel pipes are made of high-quality carbon structural steel. It is mainly made of No. 10 and No. 20 high-quality carbon structural steel. In addition to ensuring the chemical composition and mechanical properties, it must undergo hydraulic tests, curling, flaring, flattening and other tests. Hot-rolled products are delivered in a hot-rolled state, and cold-rolled (rolled) products are delivered in a heat-treated state.
High-pressure boiler seamless steel pipe: mainly used to manufacture high-quality carbon structural steel, alloy structural steel and stainless heat-resistant steel seamless steel pipes for steam boiler pipes of high pressure and above. These boiler pipes are often under high temperature and pressure. Work and pipes will also undergo oxidation and corrosion under the action of high-temperature flue gas and water vapor. Therefore, steel pipes are required to have high lasting strength, high oxidation resistance, and good organizational stability. The steel grades used are: high-quality carbon Plain structural steel grades include 20G, 20MnG, and 25MnG; alloy structural steel grades include 15MoG, 20MoG, 12CrMoG, 15CrMoG, 12Cr2MoG, 12CrMoVG, 12Cr3MoVSiTiB, etc.; rusty and heat-resistant steels commonly used 1Cr18Ni9, 1Cr18Ni11Nb high-pressure boiler tubes ensure chemical composition and mechanical In addition to performance, hydraulic pressure tests must be conducted one by one, and expansion and flattening tests must be conducted. Steel pipes are delivered in heat treated condition. In addition, there are also certain requirements for the microstructure, grain size, and decarburization layer of the finished steel pipe.

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