The manufacture of boilers and power stations requires a large number of high-pressure boiler tubes, mainly steel for boiler drums, soda pipes for boilers (including superheaters, reheaters, waterwalls and economizer pipes), boilers and power station soda pipes including header, the main cold water) steel and so on. Cold-drawn seamless steel pipe thread is mainly used for boiler water wall pipe, the actual use of the site is the boiler water wall.
Water wall is the role of precipitation into high-temperature steam, its working principle is in the tube through the cooling water, the water will be carried away by the wall heat away, at the same time, the cooling water becomes heated after the high-temperature steam. Water wall tube directly to the boiler after burning high temperature gas contact, the surface withstand high temperature radiation. If the steam flow is poor or there is air bubbles attached to the pipe wall, it will result in poor heat transfer, easy to cause the pipe wall temperature is too high, ranging from the water pipe wall to reduce the service life, increase power plant maintenance shutdown time, serious but also cause the tube wall burn through, the water flow into the boiler combustion chamber, which in turn led to the explosion of the boiler safety accident. The advantage of using internally threaded seamless steel tubes as boiler waterwall tubes is that due to the concave and convex internal threads on the inner wall, the disturbance to the mixture of water and steam can be enhanced during the circulation of the soda water in the boiler waterwall, so the water vapor does not flow flatly in the tube, But the formation of turbulent flow, this flow can avoid the bubble attached to the pipe wall, to remove the steam film to prevent deterioration of film boiling worse heat transfer, can effectively improve the wall heat transfer, the wall temperature Uniform, to avoid burning phenomenon.
These subcritical and supercritical pressure boiler thermal power plant capacity, steam parameters and the major industrial countries are basically the same, and most of the well-known foreign manufacturers to introduce boiler design technology. As these boilers in the work of the temperature and pressure parameters than the previous boiler has greatly improved the use of materials and conventional boilers are also different, first demonstrated in the choice of materials, which are made by a number of foreign boilers. The boiler designed by the factory prefers to use ASME grade materials instead of the materials used in the implementation of GB5310 standard, followed by structural changes in materials. The most typical changes are concentrated on tubes for water wall tubes. In order to improve the use of drum walls, life expectancy and heat transfer effect, more than 300,000 KW subcritical and supercritical boiler water wall tubes no longer use ordinary pipe, but the use of cold drawn seamless steel pipe, the material generally used ASME series SA210A-1, SA -210C, SA213T2 and several other brands. The internally threaded seamless steel pipe is a kind of seamless steel pipe with spiral rib on the inner surface manufactured through cold drawing process.
