The specifications of seamless carbon steel pipes are expressed in millimeters of outer diameter wall thickness.
Classification of seamless carbon steel pipes: Seamless steel pipes are divided into two categories: hot-rolled and cold-rolled (drawn) seamless steel pipes.
Hot rolled seamless carbon steel pipes is divided into general steel pipe, low and medium pressure boiler steel pipe, high pressure boiler steel pipe, alloy steel pipe, stainless steel pipe, petroleum cracking pipe, geological steel pipe and other steel pipes.
In addition to ordinary 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 (drawn) seamless steel pipes also include carbon thin-walled steel pipes, alloy thin-walled steel pipes, stainless thin-walled steel pipes and profiled steel pipes. The outer diameter of hot-rolled seamless pipes is generally greater than 32mm, with a wall thickness of 2.5-75mm. The diameter of cold-rolled seamless steel pipes can reach 6mm, the wall thickness can reach 0.25mm, and the outer diameter of thin-walled pipes can reach 5mm, with a wall thickness less than 0.25mm. Cold rolling has higher dimensional accuracy than hot rolling.
General seamless carbon steel pipe: It is made of high-quality carbon bonded steel 16Mn, 5MnV and other low alloy structural steel or 40Cr, 30CrMnSi, 45Mn2, 40MnB and other alloy steel by hot rolling or cold rolling. 10. Seamless pipes made of grade 20 low-carbon steel are mainly used for fluid transportation pipelines. Seamless pipes made of medium carbon steel such as 45 and 40Cr are used to manufacture mechanical parts, such as load-bearing parts for automobiles and tractors. Seamless steel pipes are generally used to ensure strength and flattening tests. Hot rolled steel pipes are delivered in hot rolled or heat treated condition; Cold rolling is delivered in a heat treated state.
seamless carbon steel pipes for low and medium pressure boilers: used for manufacturing various types of 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. Hot-rolled or cold-rolled seamless steel pipes made of high-quality carbon structural steel. Mainly made of No. 10 and No. 20 steel, in addition to ensuring chemical composition and mechanical properties, water pressure tests, edge rolling, expanding, flattening, and other tests must be conducted. Hot rolling is delivered in hot rolling state, and cold rolling (rolling) is delivered in heat treatment state.
High pressure boiler steel pipe: it is mainly used to manufacture high-quality carbon structural steel, alloy structural steel and stainless heat-resistant seamless steel pipes for steam boiler pipes with high pressure and above. These boiler pipes often work under high temperature and pressure, and the pipes will be oxidized and corroded under the action of high-temperature flue gas and water steam. Therefore, steel pipes are required to have high endurance strength, high oxidation resistance and good organizational stability, The steel grades used include: high-quality carbon structural steel grades include 20G, 20MnG, and 25MnG; Alloy structural steel grades 15MoG, 20MoG, 12CrMoG, 15CrMoG, 12Cr2MoG, 12CrMoVG, 12Cr3MoVSiTiB, etc; The common 1Cr18Ni9 and 1Cr18Ni11Nb high-pressure boiler tubes made of rusty and heat-resistant steel shall be subject to hydrostatic test, flaring and flattening test one by one in addition to ensuring the chemical composition and mechanical properties. Steel pipes are delivered in a heat treated state. In addition, there are certain requirements for the microstructure, grain size, and decarburization layer of finished steel pipes.
Seamless steel pipes for geological and oil drilling: To explore the structure of underground rock layers, groundwater, oil, natural gas, and mineral resources, drilling machines are used to drill wells. The extraction of oil and natural gas cannot be separated from drilling wells. Seamless steel pipes used for geological drilling are the main equipment for drilling, mainly including rock core outer pipes, rock core inner pipes, casings, drill pipes, etc. Due to the extremely complex working conditions of drilling pipes that need to penetrate into several thousand meters of geological depth, the drill pipes are subjected to stress effects such as tension, compression, bending, torsion, and uneven impact loads, as well as being subjected to mud and rock wear. Therefore, it is required that the pipes must have sufficient strength, hardness, wear resistance, and impact toughness. Steel pipes are represented by “DZ” (the Chinese phonetic prefix for geology) and a number one to represent the yield point of the steel, Commonly used steel grades include 45MnB and 50Mn of DZ45; 40Mn2 and 40Mn2Si of DZ50; 40Mn2Mo and 40MnVB of DZ55; 40MnMoB for DZ60 and 27MnMoVB for DZ65. Steel pipes are delivered in a heat treated state.
Petroleum cracking pipe: seamless carbon steel pipes used for furnace pipes, heat exchanger pipes, and pipelines in petroleum refineries. Commonly used for manufacturing high-quality carbon steel (10, 20), alloy steel (12CrMo, 15CrMo), heat-resistant steel (12Cr2Mo, 15Cr5Mo), and stainless steel (1Cr18Ni9, 1Cr18Ni9Ti). In addition to obtaining certification of chemical composition and various mechanical properties, steel pipes also need to undergo tests such as water pressure, flattening, and flaring, as well as surface quality and non-destructive testing. seamless carbon steel pipes are delivered in a heat treated state. Stainless steel pipes: Stainless steel pipes that are hot-rolled or cold-rolled with various types of stainless steel are widely used in petroleum and chemical equipment pipelines, as well as stainless steel structural parts for various purposes. In addition to ensuring chemical composition and mechanical properties, all steel pipes used to withstand fluid pressure should ensure that they pass the hydraulic test. Various specialized steel pipes should be guaranteed according to the specified conditions.