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The manufacture and use of high-pressure boiler tubes

1. Production method of high pressure boiler tube:

①Generally, the temperature of boiler tubes is below 450℃. Domestic tubes are mainly made of No. 10 and No. 20 carbon steel hot-rolled tubes or cold-drawn tubes.
②High-pressure boiler tubes are often in high temperature and high pressure conditions when they are used. The tubes will be oxidized and corroded under the action of high-temperature flue gas and water vapor. The steel pipe is required to have high durable strength, high oxidation and corrosion resistance, and good organizational stability.


 
2.Purpose of high pressure boiler tube:

①General boiler tubes are mainly used to make water wall tubes, boiling water tubes, superheated steam tubes, superheated steam tubes for locomotive boilers, large and small smoke tubes and arched brick tubes.
②High-pressure boiler tubes are mainly used to manufacture superheater tubes, reheater tubes, air guide tubes, main steam tubes, etc. of high-pressure and ultra-high-pressure boilers.
The production process of high-pressure boiler tubes varies with different steel types. Taking pearlitic chromium-molybdenum-vanadium steel as an example, the production process characteristics of boiler tubes are:
(1) The tube blank should be stripped, and the stripping amount is usually 5mm;
(2) Because the steel is relatively hard, the tube blank is often cut or sawed with oxygen;
(3) Since the thermal conductivity of chromium-molybdenum-vanadium steel is lower than that of carbon steel, the heating speed should be slightly slower, the heating temperature is 11201180℃, and the perforation temperature is 11001160℃;
(4) This kind of steel has good plasticity and low deformation resistance in the range of 10001100℃, so the perforation performance is better. The deformation parameters can be selected according to carbon steel or alloy steel (for example, 30CrMnSiA);
(5) After rolling, the steel pipe should be normalized and tempered, the normalizing temperature is 950980℃, the tempering temperature is 730750℃, and the holding time is 23h;
(6) The size tolerance of the steel pipe is relatively strict to ensure butt welding; the length of the pipe is as long as possible to help reduce the number of welds.

 

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