Classification of low and medium pressure boiler tubes

- Nov 14, 2019-

          Seamless steel tubes are divided into hot rolling and cold rolling (dial) seamless steel tubes.

          Hot-rolled seamless steel tubes are divided into general steel tubes, low and medium pressure boiler steel tubes, high pressure boiler steel tubes, alloy steel tubes, stainless steel tubes, petroleum cracking tubes, geological steel tubes and other steel tubes.

           Cold-rolled (dial-up) seamless steel tube in addition to the general steel tube, low medium pressure boiler steel tube, high pressure boiler steel tube, alloy steel tube, stainless steel tube, petroleum cracking tube, other steel tubes, also including carbon thin wall steel tube, alloy thin wall steel tube, stainless steel thin wall steel tube, special-shaped steel tube.The outer diameter of hot-rolled seamless tube is generally larger than 32mm and the wall thickness is 2.5-75mm. The diameter of cold-rolled seamless tube can reach 6mm and the wall thickness can reach 0.25mm. The outer diameter of thin-walled tube can reach 5mm and the wall thickness is less than 0.25mm.

          Generally used seamless steel tube: it is made of 10, 20, 30, 35, 45 and other high-quality carbon steel 16Mn, 5MnV and other low-alloy structural steel or 40Cr, 30CrMnSi, 45Mn2, 40MnB and other alloy steel hot rolled or cold rolled.The seamless pipe made of low carbon steel is mainly used for fluid conveying pipe.45, 40Cr and other medium carbon steel made of seamless pipe to manufacture mechanical parts, such as the car, tractor force parts.General use of seamless steel tube to ensure the strength and flattening test.Hot-rolled steel tubes are delivered in hot-rolled or heat-treated condition;Cold rolling is delivered in heat treatment condition.

          1.low medium pressure boiler tube: used for manufacturing various low medium pressure boiler, superheated steam tube, boiling water tube, water wall tube and locomotive boiler superheated steam tube, big smoke tube, small smoke tube and arch brick tube.Seamless steel tubes hot-rolled or cold-rolled with high-quality carbon structural steel.It is mainly made of no. 10 and no. 20 steel. Besides chemical composition and mechanical properties, hydraulic test, edge rolling, flaring, flattening and other tests should be done.Hot rolling delivery in hot rolling state, cold rolling (dial) delivery in heat treatment state.

          2. high-pressure boiler tubes: mainly used in the manufacture of high pressure and over pressure steam boiler pipes, etc. With high quality carbon structural steel, alloy steel and stainless heat resistant steel seamless steel tube, these often under high temperature and high pressure boiler tube, tube in high temperature flue gas and steam will happen under the action of oxidation and corrosion, so the steel pipe with high rupture strength, high oxidation resistance, and have good organizational stability, using steel grade are: high quality carbon structural steel grade 20 g, 20 MNG, 25 MNG;Alloy structural steel 15MoG, 20MoG, 12CrMoG, 15CrMoG, 12Cr2MoG, 12CrMoVG, 12Cr3MoVSiTiB, etc.Rusted heat resistant steel commonly used 1Cr18Ni9, 1Cr18Ni11Nb high pressure boiler tube in addition to ensure the chemical composition and mechanical properties, to be done one by one hydraulic test, to do flaring, flattening test.Steel tubes are delivered in heat treatment condition.In addition, the finished steel tube microstructure, grain size, decarburization layer also have certain requirements.

          3. Seamless steel pipe for geological drilling and oil drilling: to explore the structure of underground strata, underground water, oil, natural gas and mineral resources, drilling Wells.Oil, natural gas extraction is more inseparable from drilling Wells, geological drilling for oil drilling with seamless steel pipe is the main drilling equipment, mainly including core outer pipe, core inner pipe, casing, drill pipe and so on.Due to the drilling pipe to go deep into the thousands of meters formation depth work, working conditions is very complex, drill pipe under pull, pressure, bending, torsion and uneven impact load stress, but also by mud, rocks and wear, therefore, requires tubing must have sufficient strength, hardness, wear resistance and impact toughness, steel pipe steel with "DZ" pinyin "(geology) plus number one on behalf of the steel yield point, said common steel grade DZ45 MNB 45, 50 mn;DZ50 40Mn2, 40Mn2Si;DZ55 40Mn2Mo, 40MnVB;40MnMoB of DZ60, 27MnMoVB of DZ65.All steel tubes are delivered in heat treatment condition.

           4. Petroleum cracking pipe: seamless pipe for furnace pipe, heat exchanger pipe and pipe of petroleum refinery.Commonly used high quality carbon steel (10, 20), alloy steel (12CrMo, 15CrMo), heat resistant steel (12Cr2Mo, 15Cr5Mo), stainless steel (1Cr18Ni9, 1Cr18Ni9Ti) manufacturing.In addition to the chemical composition and various mechanical properties of the steel pipe, water pressure, flattening, flaring and other tests, as well as surface quality and non-destructive inspection should be ensured.Steel tubes are delivered in heat treatment condition.Stainless steel tube: with various stainless steel hot rolled, cold rolled stainless steel tube, widely used in petroleum, chemical equipment pipelines and various USES of stainless steel structural parts, in addition to the chemical components and mechanical properties should be guaranteed, where used to withstand the fluid pressure of steel pipe to ensure that the hydraulic test qualified.All kinds of special steel tube should assure the condition according to the regulation.

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