Basic Classification Knowledge Of Steel Pipes

High-pressure boiler tubes: high-quality carbon structural steels, alloy structural steels and stainless steel-resistant seamless steel tubes for steam boiler pipes mainly used to manufacture high-pressure and above pressures. These boiler tubes are often operated under high temperature and high pressure. The tube will also oxidize and corrode under the action of high temperature flue gas and water vapor. Therefore, the steel pipe is required to have high durability, high oxidation resistance and good structural stability.

Generally, the steel grades are: high-quality carbon structural steel grades (20G, 20MnG, 25MnG); alloy structural steel grades (15MoG, 20MoG, 12CrMoG, 15CrMoG, 12Cr2MoG, 12CrMoVG, 12Cr3MoVSiTiB), etc.; (1Cr18Ni9, 1Cr18Ni11Nb). In addition to ensuring chemical composition and mechanical properties, high-pressure boiler tubes must be hydrostatically tested one by one, and flaring and flattening tests are required. The steel pipe is delivered in a heat treated state. In addition, there are certain requirements for the microstructure, grain size and decarburization layer of the finished steel pipe.Seamless steel pipes for geological drilling and oil drilling: Drilling wells for drilling underground structures, groundwater, oil, natural gas and mineral resources. Oil and natural gas are inseparable from well drilling. The seamless steel pipe for oil drilling for geological drilling is the main equipment for drilling, mainly including core outer tube, core inner tube, casing and drill pipe. Because the drilling pipe is to be deep into the depth of several kilometers of ground, the working conditions are extremely complicated, and the drill pipe is subjected to stress such as tension, pressure, bending, torsion and unbalanced impact load, and is also subject to mud and rock wear.Spiral submerged arc pipe: It is made by rolling a low carbon carbon structural steel or a low alloy structural steel strip into a tube blank at a certain angle of a helix (called a forming angle), and then welding the pipe joint to make it narrower. Strip steel produces large diameter steel pipes. Spiral welded pipe is mainly used for oil and natural gas transmission pipelines, and its specifications are expressed by outer diameter wall thickness. Spiral welded pipes are single-sided welded and double-sided welded. The welded pipe shall ensure that the hydraulic test and the tensile strength and cold bending performance of the weld are in compliance with the regulations.

Therefore, it is required that the pipe must have sufficient strength, hardness, wear resistance and impact toughness. The steel for steel pipe uses "DZ" (the gravitational Chinese pinyin prefix) plus the number one for the steel yield point. The commonly used steel number is DZ45. (45MnB, 50Mn); (40Mn2, 40Mn2Si) of DZ50; (40Mn2Mo, 40MnVB) of DZ55; (40MnMoB) of DZ60; (27MnMoVB) of DZ65. The steel pipes are delivered in a heat treated state.

Petroleum cracking tubes: seamless tubes for furnace tubes, heat exchanger tubes and pipes used in petroleum refineries. It is made of high quality carbon steel (10, 20), alloy steel (12CrMo, 15CrMo), heat resistant steel (12Cr2Mo, 15Cr5Mo), stainless steel (1Cr18Ni9, 1Cr18Ni9Ti). In addition to the chemical composition and various mechanical properties, the steel pipe must also ensure water pressure, flattening, flaring and other tests, as well as surface quality and non-destructive testing. The steel pipe is delivered under heat treatment.

Stainless steel pipe: It is widely used in stainless steel pipe for hot and cold rolling of stainless steel. It is widely used in petroleum, chemical equipment pipelines and stainless steel structural parts for various purposes. In addition to ensuring chemical composition and mechanical properties, it is used as a steel pipe subjected to fluid pressure. To ensure that the water pressure test is qualified. All kinds of special steel pipes should be guaranteed according to the regulations.