Classification methods for steel pipes

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Depending on the manufacturing process, seamless steel pipes are further divided into hot-rolled (extruded) seamless steel pipes and cold-drawn (rolled) seamless steel pipes. Cold-drawn (rolled) tubes are further divided into round tubes and shaped tubes. Process flow overview: Hot rolling (extrusion of seamless steel tubes): Round tube billet → Heating → Piercing → Three-roll skew rolling, continuous rolling or extrusion → Tube removal → Dimensioning (or reduction in diameter) → Cooling → Billet tube → Straightening → Hydrostatic testing (or flaw detection) → Marking → Storage. Cold-drawn (rolled) seamless steel tubes: round tube billet → heating → piercing → end forming → annealing → pickling → oiling (copper plating) → multiple passes of cold drawing (cold rolling) → tube blank → heat treatment → straightening → hydrostatic testing (flaw detection) → marking → storage. Seamless steel pipes are classified into the following types depending on their uses: GB/T8162 (seamless steel pipes for structural use). It is mainly used in general structures and mechanical structures. Its representative materials (grade numbers): carbon steel 20, 45 steel ； Alloy steels such as Q345, 20Cr, 40Cr, 20CrMo, 30-35CrMo, 42CrMo, etc. GB/T8163 (Seamless steel pipes for transporting fluids). It is mainly used for fluid conveyance pipelines in engineering and large-scale equipment. The representative materials (grade numbers) are 20, Q345, etc. GB3087 (seamless steel tubes for low and medium pressure boilers). Primarily used for pipes that transport low and medium pressure fluids in industrial and domestic boilers. The representative materials are steel grades 10 and 20. GB5310 (Seamless steel tubes for high-pressure boilers). It is mainly used for high-temperature and high-pressure fluid transfer headers and pipes in power plant and nuclear power plant boilers. Representative materials include 20G, 12Cr1MoVG, 15CrMoG, etc. GB5312 (Seamless steel tubes for ships – carbon steel and carbon-manganese steel). Mainly used for Class I and II pressure-resistant pipes for marine boilers and superheaters, etc. The representative materials include steel grades such as 360, 410, and 460.  GB1479 (Seamless steel tubes for high-pressure fertilizer equipment). It is mainly used for pipes that transport high-temperature and high-pressure fluids in fertilizer production equipment. The representative materials include 20, 16Mn, 12CrMo, 12Cr2Mo, etc. GB9948 (Seamless steel tubes for petroleum cracking). It is mainly used in boilers, heat exchangers, and fluid transport pipelines in oil refineries. The representative materials include 20, 12CrMo, 1Cr5Mo, 1Cr19Ni11Nb, etc. GB18248 (seamless steel tubes for gas cylinders). It is mainly used for manufacturing various gas and hydraulic cylinders. The representative materials include 37Mn, 34Mn2V, 35CrMo, etc. GB/T17396 (Hot-rolled seamless steel tubes for hydraulic struts). It is mainly used to manufacture hydraulic supports and cylinders for coal mines, as well as other hydraulic cylinders and columns. The representative materials include 20, 45, 27SiMn, etc. GB3093 (High-pressure seamless steel tubes for diesel engines). Mainly used for high-pressure fuel pipes in diesel engine injection systems. Its steel pipes are generally cold-drawn pipes, with 20A being the representative material. GB/T3639 (Precision seamless steel tubes drawn or rolled cold). Steel pipes primarily used in mechanical structures and carbon compression equipment, requiring high dimensional accuracy and good surface finish. Typical materials include 20 and 45 steel, etc. GB/T3094 (Cold-drawn seamless steel tubes – Special-shaped steel tubes). It is mainly used to manufacture various structural components and parts, with materials consisting of high-quality carbon structural steel and low-alloy structural steel. GB/T 8713 (Seamless steel tubes with precise inner diameters for hydraulic and pneumatic cylinders). Primarily used to produce cold-drawn or cold-rolled seamless steel tubes with precise inner diameter dimensions for use in hydraulic and pneumatic cylinder barrels. The representative materials include 20, 45 steel, etc. GB13296 (Stainless steel seamless tubes for boilers and heat exchangers). It is mainly used in boilers, superheaters, heat exchangers, condensers, catalytic tubes, etc. in chemical enterprises. High-temperature, high-pressure, and corrosion-resistant steel pipes are used. The representative materials include 0Cr18Ni9, 1Cr18Ni9Ti, 0Cr18Ni12Mo2Ti, etc. GB/T14975 (Seamless stainless steel tubes for structural use). Steel pipes that are resistant to atmospheric and acid corrosion and possess a certain degree of strength, primarily used in general structures (such as hotel and restaurant decorations) as well as in the mechanical systems of chemical enterprises. Its representative materials include 0-3Cr13, 0Cr18Ni9, 1Cr18Ni9Ti, 0Cr18Ni12Mo2Ti, etc. GB/T14976 (Stainless steel seamless pipes for fluid transport). Primarily used for pipes transporting corrosive media. The representative materials include 0Cr13, 0Cr18Ni9, 1Cr18Ni9Ti, 0Cr17Ni12Mo2, 0Cr18Ni12Mo2Ti, etc. YB/T5035 (Seamless steel tubes for automobile half-shaft sleeves). It is mainly used for producing hot-rolled seamless steel pipes made of high-quality carbon structural steel and alloy structural steel, which are utilized in the manufacture of automotive half-shaft sleeves and axle tubes for drive axles. The representative materials include 45, 45Mn2, 40Cr, 20CrNi3A, etc. API SPEC5CT (Specification for Casing and Tubing) is a standard developed and published by the American Petroleum Institute (abbreviated as “API”), and it is used worldwide. Among them, casing: a pipe that extends from the ground surface into the borehole to serve as a lining for the well wall; these pipes are connected to each other via couplings. The main materials are steel grades such as J55, N80, and P110, as well as steel grades like C90 and T95 that are resistant to hydrogen sulfide corrosion. Its low-grade steels (J55, N80) can be used for welded steel pipes. Production tubing: Tubing inserted from the surface into the casing down to the oil layer; the individual sections of tubing are connected to each other via couplings or as a single piece. Its function is then for the pump to transport the oil from the oil layer to the surface through the oil pipes. The main materials are steel grades such as J55, N80, P110, as well as C90 and T95, which are resistant to hydrogen sulfide corrosion. Its low-grade steels (J55, N80) can be used for welded steel pipes. API SPEC 5L (Pipeline Steel Specification) was developed and published by the American Petroleum Institute, and is used worldwide. Piping pipes: They are used to transport oil, gas, or water that emerges from the ground through pipelines to petroleum and natural gas processing facilities. Piping pipes come in two types: seamless and welded pipes. Their ends can be flat, threaded, or socketed; the methods of connection include end welding, coupling connection, and socket fitting connection, among others. The main materials for this pipe are steel grades such as B, X42, X56, X65, and X70. The raw materials used for welded steel pipes are steel plates or strips. Depending on their material and manufacturing process, welded steel pipes are classified into furnace-welded pipes, electric-welded (resistance-welded) pipes, and automatic arc-welded pipes. Depending on the welding method, they are divided into straight-seam welded pipes and spiral-welded pipes. Based on their end shape, they are divided into round welded pipes and shaped welded pipes (square, flat, etc.). Depending on their applications, they are further classified into the following types: GB/T3091 (galvanized welded steel pipes for low-pressure fluid transport). Primarily used for transporting fluids at relatively low pressures such as water, gas, air, oil, and hot water or steam for heating, as well as for other applications. Its representative material is Q235A grade steel. GB/T3092 (Galvanized welded steel pipes for low-pressure fluid transport). Primarily used for transporting fluids under relatively low pressure such as water, gas, air, oil, and heating water or steam, as well as for other applications. Its representative material is Q235A grade steel. GB/T14291 (Welded steel pipes for conveying fluids in mining applications). Straight-seam welded steel pipes mainly used for mine air compression, drainage, and gas drainage. Its representative materials are Q235A and grade B steel. GB/T14980 (Large-diameter electric welded steel pipes for low-pressure fluid transport). It is mainly used for transporting low-pressure fluids such as water, sewage, gas, air, and heating steam, as well as for other purposes. Its representative material is Q235A grade steel. GB/T12770 (Welded stainless steel pipes for mechanical structures). It is mainly used in machinery, automobiles, bicycles, furniture, hotel and restaurant decoration, as well as other mechanical components and structural parts. The representative materials include 0Cr13, 1Cr17, 00Cr19Ni11, 1Cr18Ni9, 0Cr18Ni11Nb, etc. GB/T12771 (Stainless steel welded pipes for fluid transport). It is mainly used for transporting low-pressure corrosive media. The representative materials include 0Cr13, 0Cr19Ni9, 00Cr19Ni11, 00Cr17, 0Cr18Ni11Nb, 0017Cr17Ni14Mo2, etc