Steel pipe, as an important part of steel products, is divided into seamless steel tube (round billet) and welded steel pipe (plate and strip) for its manufacturing process and different shape of tube billet. (1) Seamless steel tubes because of their different manufacturing processes, but also divided into hot-rolled (extruded) seamless steel tubes and drawing (rolled) seamless steel tubes. Drawing (rolling) tube is divided into circular tubes and special-shaped tubes. A． Process Overview Hot-rolled (extruded seamless steel tube): round tube billet → heating → perforation → three-roll skew rolling, continuous rolling or extrusion → removal → sizing (or reducing) → cooling → billet Tube → straightening → hydrostatic test (or flaw detection) → marking → warehousing. Drawing (rolled) seamless steel tubes: round tube billet → heating → perforation → head → annealing → pickling → oil (copper plated) → multi-channel cold drawing (cold rolling) → billet Tube → heat treatment → straightening → water pressure test (flaw detection) → mark → warehousing. b． Seamless steel tubes, because of their different uses are divided into the following varieties: gb/t8162-1999 (structural seamless steel tube). Mainly used in general structure and mechanical structure. Its representative material (grade): Carbon steel 20, 45th steel, Alloy steel Q345, 20Cr, 40Cr, 20CrMo, 30-35crmo, 42CrMo and so on. gb/t8163-1999 (seamless pipe for conveying fluid). Mainly used in engineering and large-scale equipment conveying fluid pipelines. The representative material (grade) is 20, Q345 and so on. gb3087-1999 (Low medium pressure boiler seamless steel tube). Mainly used in industrial boilers and living boilers conveying low medium pressure fluid pipeline. The representative material is 10, 20th steel. gb5310-1995 (high pressure boiler seamless steel tube). Mainly used in power plant and nuclear power plant boilers high temperature, high pressure of the transport fluid collection box and pipeline. The representative material is 20G, 12CR1MOVG, 15CrMoG and so on. gb5312-1999 (marine carbon steel and carbon-manganese steel seamless steel tube). Mainly used in marine boilers and superheater I, II-class pressure-resistant tubes. The representative material is 360, 410, 460 steel grade and so on. gb1479-2000 (high pressure chemical fertilizer equipment with seamless steel tube). Mainly used in chemical fertilizer equipment transport high-temperature high-pressure fluid pipeline. The representative material is 20, 16Mn, 12CrMo, 12cr2mo and so on. gb9948-1988 (seamless steel pipe for petroleum cracking). It is mainly used in the boiler, heat exchanger and conveying fluid pipeline of petroleum smelting plant. Its representative material is 20, 12CrMo, 1cr5mo, 1cr19ni11nb and so on. gb18248-2000 (seamless steel tubes for cylinders). Mainly used for making all kinds of gas, hydraulic cylinders. Its representative material is 37Mn, 34mn2v, 35CrMo and so on. gb/t17396-1998 (Hot rolled seamless steel pipe for hydraulic prop). Mainly used in the production of coal mine hydraulic support and cylinder, column, as well as other hydraulic cylinders, columns. Its representative material is 20, 45, 27SiMn and so on. gb3093-1986 (high pressure seamless steel tube for diesel engine). Mainly used in diesel injection system high-pressure tubing. Its steel pipe is generally cold drawn pipe, its representative material is 20A. gb/t3639-1983 (cold drawn or cold-rolled precision seamless steel tube). Mainly used in mechanical structure, carbon pressure equipment, the requirements of high dimensional precision, surface finish good steel pipe. Its representative material 20, 45 steel and so on. gb/t3094-1986 (cold drawn seamless steel tube profiled pipe). Mainly used for the production of various structural parts and parts, the material for high-quality carbon structural steel and low alloy structural steel. gb/t8713-1988 (seamless steel pipe for hydraulic and pneumatic cylinders). Mainly used for the production of hydraulic and pneumatic cylinder with precision diameter of the size of cold drawn or cold-rolled seamless steel tube. Its representative material is 20, 45 steel and so on. gb13296-1991 (stainless steel seamless pipe for boiler and heat exchanger). Mainly used in chemical enterprise boilers, superheater, heat exchangers, condensers, catalytic tubes and so on. High temperature, high pressure, corrosion-resistant steel pipe. Its representative material for 0cr18ni9, 1Cr18Ni9Ti, 0cr18ni12mo2ti and so on. gb/t14975-1994 (stainless steel seamless pipe for structure). Mainly used in general structure (hotel, hotel decoration) and chemical enterprise mechanical structure of the atmospheric resistance, acid corrosion and has a certain strength of steel pipe. Its representative material for 0-3cr13, 0Cr18Ni9, 1Cr18Ni9Ti, 0cr18ni12mo2ti and so on. gb/t14976-1994 (seamless steel pipe for fluid conveying). Piping used mainly for conveying corrosive media. Representative materials for 0cr13, 0Cr18Ni9, 1Cr18Ni9Ti, 0cr17ni12mo2, 0cr18ni12mo2ti and so on. yb/t5035-1993 (seamless steel tube for automobile axle casing). It is mainly used for the production of high quality carbon structural steel and alloy structural steel seamless pipe for automobile axle casing and drive axle axle shell. Its representative material is 45, 45mn2, 40Cr, 20crni3a and so on. API spec5ct-1999 (Casing and Tubing specification) is compiled and released by the American Petroleum Society (American Petreleum Instiute, abbreviation "api") worldwide. Wherein: casing: from the ground surface into the drilling, as the lining of the pipe, the pipe is connected through the coupling. The main material for J55, N80, P110 and other steel grade, as well as corrosion-resistant C90, T95 and other steel grade. Its low steel grade (J55, N80) can be welded steel pipe. Tubing: A pipe inserted into a casing from the surface to the reservoir, through which the pipe is connected through a collar or a whole. The effect is that the oil pump will be transported to the ground by tubing. The main materials are J55, N80, P110, and corrosion-resistant C90, T95 and other steel grade. Its low steel grade (J55, N80) can be welded steel pipe. API Spec 5l-2000 (piping specification) is compiled and released by the American Petroleum Institute and is common throughout the world. Pipeline: The oil, gas, or water that is used to deliver the shaft to the oil and gas industry. Pipeline pipe includes two kinds of seamless and welded pipe, its pipe end has flat end, with threaded end and socket end, its connection mode is end head welding, coupling connection, socket connection and so on.
The main material for the tube is B, X42, X56, X65, X70 and other steel grade.