Seamless steel pipes have a hollow section and are used in large quantities as pipelines for transporting fluids, such as pipelines for transporting oil, natural gas, gas, water and certain solid materials. Compared with solid steel such as round steel, steel pipe is lighter when the bending and torsion strength is the same. It is a kind of economical cross-section steel, which is widely used in the manufacture of structural parts and mechanical parts. 1. The diameter of the pipe can be divided into outer diameter. , Inner diameter, nominal diameter. The outer diameter of a seamless steel pipe is indicated by the letter D, followed by the size and wall thickness of the outer diameter. For example, a seamless steel pipe with an outer diameter of 108, with a wall thickness of 5MM, is represented by D108*5, plastic pipe It is also expressed by outer diameter, such as De63. Others such as reinforced concrete pipes, cast iron pipes, galvanized steel pipes, etc. are expressed by DN. In the design drawings, the nominal diameter is generally used to express. The nominal diameter is artificially specified for the convenience of design, manufacture and maintenance. One of the standards, which is also the nominal diameter, is the specification name of the pipe (or fitting).
2. The nominal diameter of the pipe is not equal to its inner diameter and outer diameter. For example, there are several kinds of seamless steel pipes with a nominal diameter of 100MM, such as 102*5, 108*5, 108 is the outer diameter of the pipe, and 5 is the pipe’s Therefore, the inner diameter of the steel pipe is (108*5-5)=98MM, but it is not exactly equal to the difference between the outer diameter of the steel pipe minus twice the wall thickness. It can also be said that the nominal diameter is close to the inner diameter, but not The specification name of a pipe diameter equal to the inner diameter. The nominal diameter is used in the design drawings. The purpose is to determine the structural dimensions and connection dimensions of pipes, fittings, valves, flanges, gaskets, etc. according to the nominal diameter. The nominal diameter is used The symbol DN means that if the outer diameter is used in the design drawings, a pipe specification comparison table should also be made to indicate the nominal diameter and wall thickness of a certain pipe.
What are the classifications of steel pipes?
1. According to production methods, seamless steel pipes can be divided into: hot-rolled seamless pipes, cold drawn pipes, precision steel pipes, hot expanded pipes, cold spinning pipes, and extruded pipes. Seamless steel tubes are made of carbon steel or alloy steel, and can be divided into hot-rolled and cold-rolled (drawn).
2. Welded steel pipes are divided into furnace welded pipes, electric resistance welded (resistance welded) pipes and automatic arc welded pipes due to their different welding processes. Due to their different welding forms, they are divided into two types: straight seam welded pipes and spiral welded pipes. Because of their end shapes, they are divided into round Shaped welded pipe and special-shaped (square, flat, etc.) welded pipe. Welded steel pipes are formed by welding steel plates rolled into a tube shape with butt seams or spiral seams. In terms of manufacturing methods, they are divided into welded steel pipes for low-pressure fluid transportation, spiral seam electric welded steel pipes, direct coil welded steel pipes, and electric welded pipes. Seamless steel pipes can be used for liquid pressure pipes and gas pipes in various industries. Welded pipelines can be used for water pipelines, gas pipelines, heating pipelines, electrical pipelines, etc.
The steel pipe specification size table, the above text gives you an introduction, people should already know it after reading it, divided into so many sizes, it happens to be able to meet the different needs of people, what are the classifications of steel pipes? Classification has a slightly different characteristic. After reading it, people should have a lot of understanding and understanding. For example, oil drill pipes, automobile transmission shafts, bicycle frames and steel scaffolds used in construction are used to make ring parts with steel pipes, which can improve material utilization, simplify manufacturing procedures, and save materials and processing man-hours, such as rolling bearing rings, jack sleeves, etc. , Has been widely used to manufacture steel pipes. Steel pipes are also an indispensable material for various conventional weapons. Gun barrels and barrels are all made of steel pipes. Steel pipes can be divided into round pipes and special-shaped pipes according to different cross-sectional area shapes. Since the circle area is the largest under the condition of the same circumference, more fluid can be transported with a circular tube. In addition, when the ring section is subjected to internal or external radial pressure, the force is relatively uniform. Therefore, most steel pipes are round pipes.
Executive standards and corresponding materials
1.GB/T8162-1999 (Seamless steel pipe for structure). Mainly used for general structure and mechanical structure. Its representative materials (brands): carbon steel, 20, 45 steel; alloy steel Q345, 20C galvanized steel pipe prices r, 40Cr, 20CrMo, 30-35CrMo, 42CrMo, etc.
2.GB/T8163-1999 (Seamless steel pipe for conveying fluid). Mainly used in engineering and large-scale equipment to transport fluid pipelines. The representative ceramic composite steel pipe material (brand) is 20, Q345, etc.
3.GB3087-1999 (Seamless steel pipe for medium pressure boiler with low Wuxi seamless steel pipe). Mainly used in industrial boilers and domestic boilers to transport low and medium pressure fluid pipelines. Representative materials are 10 and 20 steel.
4.GB5310-1995 (Seamless steel tubes for high-pressure boilers). It is mainly used for high temperature and high pressure fluid headers and pipelines in power stations and Tianjin seamless steel tube nuclear power plant boilers. Representative materials are 20G, 12Cr1MoVG, 15CrMoG steel pipe scaffolding, etc.
5.GB5312-1999 (Carbon steel and carbon-manganese steel seamless steel tubes for ships). China's seamless steel pipe network is mainly used for I and II pressure pipes for ship boilers and superheaters. Representative materials are 360, 410, 460 steel grades, etc.
6.GB1479-2000 (Seamless steel pipes for high-pressure fertilizer equipment). It is mainly used for high-temperature and high-pressure fluid pipelines sent by Tianjin Pipe Group to fertilizer equipment. Representative materials are 20, 16Mn, 12CrMo, 12Cr2Mo, etc.
7.GB9948-1988 (seamless steel pipe for petroleum cracking). Mainly used in oil smelter boilers, heat exchange scaffolding steel pipe price devices and fluid pipelines. Its representative materials are 20, 12CrMo, 1Cr5Mo, 1Cr19Ni11Nb, etc.
8.GB18248-2000 (Seamless steel pipe for gas cylinders). Mainly used to make various gas welded steel pipes and hydraulic cylinders. Its representative materials are 37Mn, 34Mn2V, 35CrMo, etc.
9. Petroleum drilling pipe (YB528-65) is a seamless steel pipe with inner or outer thickening at both ends of oil drilling. Steel pipes are divided into two types: wire and non-wired. Wired pipes are connected by joints, and non-wired pipes are connected with tool joints by butt welding.
10. Carbon steel seamless steel pipes for ships (GB5312-2009) are carbon steel seamless steel pipes used in the manufacture of Class I pressure piping systems, Class II pressure piping systems, boilers and superheaters. The working temperature of carbon steel seamless pipe wall does not exceed 450℃, and that of alloy steel seamless pipe wall exceeds 450℃.
11. Seamless steel pipes for automobile axle sleeves (GB3088-82) are high-quality carbon structural steel and alloy structural steel hot-rolled seamless steel pipes for the manufacture of automobile axle sleeves and drive axle axle tubes.
12. High-pressure oil pipes for diesel engines (GB3093-2002) are cold-drawn seamless steel pipes used to manufacture high-pressure pipes for diesel engine injection systems.
13. Precision inner diameter seamless steel pipes for hydraulic and pneumatic cylinders (GB8713-88) are cold drawn or cold-rolled precision seamless steel pipes with precise inner diameters for the manufacture of hydraulic and pneumatic cylinders.
14. Cold-drawn or cold-rolled precision seamless steel pipe (GB3639-2000) is a cold-drawn or cold-rolled precision seamless steel pipe for mechanical structures and hydraulic equipment with high dimensional accuracy and good surface finish.
15. The structural stainless steel seamless steel pipe (GB/T14975-2002) is a hot-rolled stainless steel made of corrosion-resistant pipes and structural parts and parts widely used in the chemical, petroleum, textile, medical, food, machinery and other industries. Extruded, expanded) and cold drawn (rolled) seamless steel tubes.
16. Stainless steel seamless steel tubes for fluid transportation (GB/T14976-2002) are hot-rolled (extruded, expanded) and cold-drawn (rolled) seamless steel tubes made of stainless steel used for fluid transportation.
17. Shaped seamless steel pipe is a general term for seamless steel pipes with cross-sectional shapes other than round pipes. According to the different shape and size of the steel pipe section, it can be divided into equal wall thickness special-shaped seamless steel pipe (code D), unequal wall thickness special-shaped seamless steel pipe (code BD), variable diameter special-shaped seamless steel pipe (code BJ). Special-shaped seamless steel pipes are widely used in various structural parts, tools and mechanical parts. Compared with round pipes, special-shaped pipes generally have larger moments of inertia and section modulus, and have greater bending and torsion resistance, which can greatly reduce structural weight and save steel.
