Description
Cold rolled (drawn) seamless steel pipe includes carbon thin-walled steel pipe, alloy thin-walled steel pipe, stainless steel thin-walled steel pipe, stainless thin-walled steel pipe and special-shaped steel pipe in addition to general steel pipe, low and medium pressure boiler steel pipe, high-pressure boiler steel pipe, alloy steel pipe, petroleum cracking pipe and other steel pipes. The outer diameter of hot-rolled seamless pipe is generally greater than 32mm and the wall thickness is 2.5-75mm. The diameter of cold-rolled seamless steel pipe can be up to 6mm and the wall thickness can be up to 0.25mm. The outer diameter of thin-walled pipe can be up to 5mm and the wall thickness is less than 0.25mm. Cold rolling has higher dimensional accuracy than hot rolling.It is made of high-quality carbon steel such as 10, 20, 30, 35 and 45, low-alloy structural steel such as 16Mn and 5mnv, or alloy steel such as 40Cr, 30CrMnSi, 45Mn2 and 40MnB. 10. Seamless pipes made of low carbon steel such as 20 are mainly used for fluid transmission pipelines. Seamless pipes 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, the strength and flattening test of seamless steel pipe shall be ensured. Hot rolled steel pipes shall be delivered in hot rolling state or heat treatment state; Cold rolling is delivered in heat treated condition.It is used to manufacture all kinds of 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 seamless steel pipe made of high-quality carbon structural steel. It is mainly made of 10 and 20 steel. In addition to ensuring chemical composition and mechanical properties, hydrostatic test, crimping, flaring, flattening and other tests shall be carried out. Hot rolling shall be delivered in hot rolling state, and cold rolling (dialing) shall be delivered in heat treatment state.Seamless steel pipe for low and medium pressure boiler
Seamless steel pipe for general use
High pressure boiler steel pipe
It is mainly used to manufacture high-quality carbon structural steel, alloy structural steel and stainless heat-resistant steel seamless steel pipes for steam boiler pipes with high pressure and above. These boiler pipes often work under high temperature and high pressure. The pipes will also undergo oxidation and corrosion under the action of high-temperature flue gas and steam. Therefore, the steel pipes are required to have high lasting strength and high oxidation resistance, The steel grades adopted are: high-quality carbon structural steel, and the steel grades are 20g, 20mng and 25mng; Alloy structural steel grades: 15mog, 20mog, 12crmog, 15CrMoG, 12CR2MOG, 12crmovg, 12Cr3MoVSiTiB, etc; In addition to ensuring chemical composition and mechanical properties, 1Cr18Ni9 and 1cr18ni11nb high-pressure boiler tubes commonly used in rusty heat-resistant steel shall be subject to hydrostatic test, flaring and flattening test one by one. Steel pipes shall be delivered in heat treated condition. In addition, there are certain requirements for the microstructure, grain size and decarburization layer of the finished steel pipe.Seamless steel pipe for geological drilling and oil drilling
In order to explore the underground rock structure, groundwater, oil, natural gas and mineral resources, drilling rigs are used to drill wells. Oil and gas exploitation is inseparable from drilling. Seamless steel pipes for geological drilling and oil drilling are the main equipment for drilling, mainly including core outer pipe, core inner pipe, casing, drill pipe, etc. As the drilling pipe needs to work at the depth of several thousand meters, the working conditions are extremely complex, the drill pipe bears the stress effects of tension, compression, bending, torsion and unbalanced impact load, and is also worn by mud and rock. Therefore, the pipe must have sufficient strength, hardness, wear resistance and impact toughness, The steel for steel pipe is represented by "DZ" (Geological Chinese Pinyin prefix) plus a number to represent the steel yield point. The commonly used steel grades are 45mnb and 50Mn of dz45; 40Mn2 and 40mn2si of dz50; 40mn2mo and 40mnvb of dz55; 40mnmob of DZ60 and 27mnmovb of dz65. Steel pipes are delivered in heat-treated condition.Petroleum cracking tube
Seamless tubes for furnace tubes, heat exchanger tubes and pipes in petroleum refineries. It is usually made of high-quality carbon steel (10, 20), alloy steel (12CrMo, 15CrMo), heat-resistant steel (12cr2mo, 15cr5mo) and stainless steel (1Cr18Ni9, 1Cr18Ni9Ti). In addition to the chemical composition and various mechanical properties of the steel pipe, it is also necessary to ensure the hydrostatic, flattening, flaring and other tests, as well as the surface quality and nondestructive testing. Steel pipes shall be delivered under heat treatment. Stainless steel pipe: all kinds of stainless steel hot-rolled and cold-rolled stainless steel pipes are widely used in petroleum and chemical equipment pipes and stainless steel structural parts for various purposes. In addition to ensuring chemical composition and mechanical properties, all steel pipes used to bear fluid pressure shall be qualified in hydrostatic test. Various special steel pipes shall be guaranteed according to the specified conditions. According to incomplete statistics, there are more than 240 seamless pipe production enterprises and more than 250 seamless steel pipe units in China, with an annual capacity of more than 4.5 million tons. In terms of caliber< φ 76, accounting for 35%< φ 159-650, accounting for 25%. In terms of varieties, 1.9 million tons of general-purpose pipes, accounting for 54%; 760000 tons of oil pipes, accounting for 5.7%; 150000 tons of hydraulic prop and precision pipe, accounting for 4.3%; Stainless pipe, bearing pipe and automobile pipe are 50000 tons, accounting for 1.4%. The billet is sent to the furnace for heating at a temperature of about 1200 degrees Celsius. The fuel is hydrogen or acetylene. The temperature control in the furnace is the key problem. After the round tube billet is discharged from the furnace, it should be pierced through the pressure piercer. Generally, the more common piercer is the conical roll piercer. This piercer has high production efficiency, good product quality, large perforation expansion and can wear a variety of steel grades. After perforation, the round tube blank is successively rolled by three roll cross rolling, continuous rolling or extrusion. After extrusion, take off the pipe for sizing. The sizing machine rotates into the steel embryo at high speed through the conical drill to form a steel pipe. The inner diameter of the steel pipe is determined by the outer diameter length of the sizing machine bit. After sizing, the steel pipe enters the cooling tower and is cooled by water spray. After cooling, the steel pipe will be straightened. After straightening, the steel pipe is sent to the metal flaw detector (or hydrostatic test) by the conveyor belt for internal flaw detection. If there are cracks, bubbles and other problems inside the steel pipe, they will be detected. Steel pipes should be strictly selected by hand after quality inspection. After the steel pipe is inspected, the number, specification, production batch number, etc. shall be sprayed with paint. And hoisted into the warehouse by crane.