What is high-pressure seamless steel pipe? It is a type of boiler tube and belongs to the seamless steel tube category. The manufacturing method is the same as that of seamless steel tubes, but there are certain strict requirements for the steel types used for manufacturing steel tubes. Since high-pressure boiler tubes are often used in high-temperature and high-pressure conditions, high-pressure boiler tubes are mainly used to manufacture superheater tubes, reheater tubes, steam guide tubes, and main steam tubes for high-pressure and ultra-high-pressure boilers.
Low and medium pressure boiler tubes GB3087-2008, high pressure boiler tubes GB5310-2008 are used to manufacture various structures of low and high pressure boiler superheated steam tubes, boiling water tubes and locomotive pots. High-quality carbon structural steel hot-rolled and cold-drawn (rolled) seamless steel tubes for superheated steam pipes, large smoke pipes, small smoke pipes and arch brick pipes used in furnaces. Seamless steel pipe for structure (GB/T8162-2008) is a seamless steel pipe for general structure and mechanical structure.
Specifications and appearance quality: GB5310-2008 "Seamless Steel Tubes for High Pressure Boilers" The outer diameter of the hot-rolled tube is 22-530mm, and the wall thickness is 20-70mm. The cold drawn (cold rolled) tube has an outer diameter of 10 to 108 mm and a wall thickness ranging from 2.0 to 13.0 mm.
Special-shaped seamless steel tubes are the general term for seamless steel tubes with cross-sectional shapes other than round tubes. According to the different shape and size of the steel tube cross 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 tubes are widely used in various structural parts, tools and mechanical parts. Compared with round tubes, shaped tubes generally have larger moments of inertia and section modulus, and have greater bending and torsion resistance, which can greatly reduce the weight of the structure and save steel.
(1) GB3087-2008 "Seamless Steel Tubes for Low and Medium Pressure Boilers". The chemical composition test method is in accordance with the relevant parts of GB222-84 and GB223 "Steel and Alloy Chemical Analysis Methods".
(2) GB5310-2008 "Seamless Steel Tubes for High Pressure Boilers". The chemical composition test method is according to the relevant parts in GB222-84 and "Chemical Analysis Methods for Iron and Steel and Alloys", GB223 "Chemical Analysis Methods for Steel and Alloys".
(3) The chemical composition inspection of imported boiler steel tubes shall be conducted in accordance with the relevant standards stipulated in the contract.
Boiler tube steel number:
(1) High-quality carbon structural steel grades are 20G, 20MnG, 25MnG.
(2) Alloy structural steel grades 15MoG, 20MoG, 12CrMoG, 15CrMoG, 12Cr2MoG, 12CrMoVG, 12Cr3MoVSiTiB, etc.
(3) The 1Cr18Ni9 and 1Cr18Ni11Nb boiler tubes commonly used for rust-resistant and heat-resistant steel should be tested for water pressure one by one in addition to ensuring the chemical composition and mechanical properties. Steel pipes are delivered in a heat-treated state.
In addition, there are certain requirements for the microstructure, grain size, and decarburized layer of the finished steel pipe.
(1) GB3087-82 "Seamless Steel Tubes for Low and Medium Pressure Boilers". Tensile test according to GB/T228-87, hydraulic test according to GB/T241-90, flattening test according to
GB/T246-97, flaring test according to GB/T242-97, cold bending test according to GB244-97.
(2) GB5310-95 "Seamless Steel Tubes for High Pressure Boilers". The tensile test, hydrostatic test and flattening test are the same as those specified in GB3087-82; the impact test is based on GB229-94, the flaring test is based on GB/T242-97, and the grain size test is based on YB/T5148-93; GB13298-91, decarburization layer inspection according to GB224-87, ultrasonic inspection according to GB/T5777-96.
(3) The physical property inspection and indicators of the imported boiler tubes are carried out in accordance with the relevant standards stipulated in the contract.
Import and export situation:
(1) The main importing countries of boiler tubes are Japan and Germany. The frequently imported specifications are 15914.2mm; 2734.0mm; 219.110.0mm; 41975mm;
406.460mm, etc. The smallest size is 31.84.5mm, and the length is generally 5-8m.
(2) In the import claim case, the ST45 seamless boiler tube imported from the German Mannesmann Steel Pipe Plant, after ultrasonic inspection, found that a small number of internal defects of the steel pipe exceeded the factory regulations and the German Steel Association standards.
(3) For alloy steel pipes imported from Germany, the steel grades are mainly 34CrMo4 and 12CrMoV. This kind of steel pipe has good high-temperature performance and is commonly used as a steel pipe for high-temperature boilers.
(4) There are many alloy tubes imported from Japan with specifications of 426.012mm5～8m; 152.48.0mm12m; 89.110.0mm6m; 101.610.0mm12m;
114.38.0mm6m; 127.08.0mm9m, etc. Implementation of Japanese industrial standard JISG3458 steel number is STPA25. This kind of steel pipe is commonly used as a matching superalloy pipe.
High-pressure seamless steel pipe is a kind of seamless pipe. The manufacturing method is the same as that of seamless pipes, but there are strict requirements for the steel grades used to manufacture steel pipes. According to the use temperature, it can be divided into two types: general boiler tube and high pressure boiler tube.
(1) The use temperature of high-pressure seamless steel pipes is below 450℃. Domestic pipes are mainly made of No. 10 and No. 20 carbon-bonded steel hot-rolled pipes or cold-drawn pipes.
(2) The high-pressure seamless steel pipe is often in high temperature and high pressure conditions when used, and the pipe will be oxidized and corroded under the action of high temperature flue gas and water vapor. The steel pipe is required to have high endurance strength, high resistance to oxidation and corrosion, and good organizational stability.
The main purpose:
(1) High-pressure seamless steel pipes are mainly used to manufacture water-cooled wall pipes, boiling water pipes, superheated steam pipes, superheated steam pipes for locomotive boilers, large and small smoke pipes and arch brick pipes.
(2) High-pressure seamless steel tubes are mainly used to manufacture high-pressure and ultra-high-pressure boiler power plant superheater tubes, reheater tubes, gas guide tubes, main steam tubes, etc.
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