water tube boilers and fire tube boilers. In a water tube boiler, water circulates inside the tubes and the outside is heated by hot gases generated in the furnace. Boiler tubes are divided into seamless tubes and welded tubes, and are made of carbon steel or alloy steel. It is widely used in steam boilers, power generation, fossil fuel plants, industrial processing plants, power plants, such as fire tube boilers/fire tube steam boilers, triangle tube boilers/triangle tube boilers, water tube boilers, smoke tube boilers. Boiler tubes can be medium pressure boiler tubes or high pressure boiler tubes.
How are boiler tubes made?
The initial manufacturing process of medium pressure boiler tubes and high pressure boiler tubes is the same, including fine drawing, surface brightening, hot rolling, cold drawing and hot expansion. However, in order to make the high pressure tubes stronger and more corrosion resistant, the following steps are taken.
Heat treatment involves the heating and cooling of high pressure boiler tubes, thereby improving toughness, hardness and wear resistance. The different steps of heat treatment include quenching, tempering and annealing.
Quenching is to improve the hardness of high pressure boiler tubes. The tubes are evenly heated to the appropriate temperature and then quickly immersed in water or oil and cooled immediately. It is then cooled in air or in the solidification zone.
Tempering is used to eliminate the brittleness of the pipe. Quenching may cause the pipe to crack or break.
Annealing eliminates internal stress in the pipe. In this process, the seamless pipe is heated to a critical temperature and then slowly cooled in ash or lime.
heat resistant boiler tube
