Boiler Tube Knowledge

- Feb 25, 2019-

20G High Pressure boiler tube is a kind of boiler tube, which belongs to the category of seamless steel pipe. The manufacturing method is the same as the seamless tube, but there are strict requirements for the steel used in the manufacture of steel tubes. 20G High-pressure boiler tubes are often used in high temperature and high pressure conditions, tubes in high temperature flue gas and water vapor under the action of oxidation and corrosion. The steel pipe is required to have high lasting strength, high antioxidant corrosion resistance, and good tissue stability. 20G High-pressure boiler tubes are mainly used to manufacture high-pressure and ultra-high-pressure boilers of superheater tubes, reheater tubes, guide pipes, main steam tubes and so on.

Low medium pressure boiler tube GB3087-1999, 20G high-pressure boiler tube GB5310-1999 is used in the manufacture of a variety of structural low-pressure boiler superheated steam pipe, boiling water pipe and locomotive boiler with superheated steam pipe, big smoke pipe, small pipe and arch brick pipe high-quality carbon structural steel hot rolling and cold drawing (rolling) seamless steel pipe.

Seamless steel pipe (GB/T8162-1999) for structural use is a seamless steel pipe for general structure and mechanical structure. Specifications and appearance quality: GB5310-95 "high-pressure boiler with seamless steel pipe" hot-rolled pipe diameter 22~530mm, wall thickness 20~70mm range.

Cold drawing (cold rolled) tube outer diameter 10~108mm, wall thickness 2.0~13.0mm range. Special-shaped seamless steel pipe is in addition to the round pipe other cross-sectional shape of seamless steel pipe general name. According to the different shape size of steel pipe section can be divided into equal wall thickness special-shaped seamless steel pipe (code-named D), unequal wall thickness special-shaped seamless steel pipe (code-named BD), variable diameter special seamless steel pipe (code-named BJ). Shaped seamless steel pipe is widely used in a variety of structural parts, tools and mechanical parts. Compared with the circular tube, the special-shaped tube generally has a larger inertial moment and section modulus, has a larger bending and torsion resistance, can greatly reduce the structure weight, save steel.

Chemical composition Inspection

(1) GB3087-82 "seamless steel pipe for low medium pressure boiler" provisions.Chemical composition test method according to GB222-84 and GB223 "iron and steel and alloy chemical analysis methods" in the relevant parts.

(2) GB5310-95 "seamless steel pipe for high pressure boiler" provisions.Chemical composition test methods according to GB222-84 and "iron and steel and alloy chemical analysis methods", GB223 "Steel and alloy chemical analysis methods" in the relevant parts.

(3) The chemical composition inspection of imported boiler steel pipe is carried out according to the relevant standards stipulated in the contract.

The boiler tube adopts steel number

(1) High-quality carbon structure steel steel number has 20G, 20MnG, 25MnG.

(2) Alloy structural steel steel number 15MoG, 20MoG, 12CrMoG, 15CrMoG, 12Cr2MoG, 12CrMoVG, P11 12Cr3MoVSiTiB and so on.

(3) Rusty heat-resistant steel commonly used 1Cr18Ni9, 1Cr18Ni11Nb boiler tube In addition to ensure chemical composition and mechanical properties, to do water pressure test by root, to do expansion, flattening test. The steel pipe is delivered in a heat treatment state.

Physical Performance Testing

(1) GB3087-82 "seamless steel pipe for low medium pressure boiler" provisions.

Tensile test according to GB/T228-87, hydraulic test According to GB/T241-90, flattening test according to GB/T246-97, expansion test according to GB/T242-97, cold bending test according to GB244-97.

(2) GB5310-95 "seamless steel pipe for high pressure boiler" provisions. Tensile test, hydraulic test and flattening test are the same as GB3087-82 regulations; impact test according to GB229-94, expansion test according to GB/T242-97, grain degree test according to YB/T5148-93; microscopic tissue test according to GB13298-91, decarbonization layer test press GB224-87,

Ultrasonic inspection according to GB/T5777-96.

(3) The physical performance inspection and indicators of imported boiler tubes are carried out in accordance with the relevant standards stipulated in the contract.

Main import and export situation

(1) 20G high-pressure boiler pipe mainly imported countries are Japan, Germany. The specifications for frequent imports are 15914.2mm;2734.0mm;219.110.0mm;41975mm;406.460mm and so on. The minimum specification is 31.84.5mm and the length is generally 5~8m.

(2) In the case of import claims, the ST45 seamless boiler tube imported by the German Menesman steel pipe factory, after ultrasonic flaw detection survey, found that the internal defects of a small number of steel tubes exceeded the regulations of the factory and the standards of the German Iron and Steel Association.

(3) The alloy steel pipe imported from Germany, the steel number mainly has 34CrMo4 and 12CrMoV and so on.This kind of steel pipe has good high temperature performance and is often used as steel pipe for high temperature boiler.

(4) Japan imports more alloy tubes, specifications have 426.012mm5~8m;152.48.0mm12m;89.110.0mm6m;101.610.0mm12m;114.38.0mm6m;127.08.0mm9m and so on. Implementation of the Japanese industrial standard JISG3458 steel number is STPA25. This kind of steel pipe is often used for supporting high temperature alloy tubes.