Along with the development of industry in the last century, the use of high pressure boilers has become necessary and sometimes catastrophic explosions have occurred. Because in the past, boilers were made of large diameter vessels under pressure, which due to internal pressure, expansion stresses inside the boilers occurred in the walls of these vessels. The proposed solution to this fundamental problem was to reduce the diameter of the pressure vessels. In fact, this reduction in diameter is the basis of the operation of pipe-water boilers. Hot gases flow inside the pipes of these water boilers and on their outer surface.
Water tube boilers are made up of containers called drums that are connected by a tube. Water circulates inside the boiler pipes and hot gases move in the vicinity of the pipes. The most important advantage of water pipe boilers is the possibility of increasing their capacity. Water tube boilers are capable of producing heaters with a pressure of 160 Atm and a temperature of 550 C and a capacity of 160 to 2200 ton / hr. Water pipe boilers are produced in smaller packages for use in the oil and petrochemical industry.
In addition to this classification, boilers are classified into single-pass, double-pass, three-pass, three-pass, and four-pass boilers based on the number of combustion gas paths entering the chimney.
In a boiler, the body must be insulated and covered with high quality fiberglass and steel sheets. Joints, welding and assembly should be measured by X-ray and the amount of stresses tolerated on it should be tested.
Boiler ventilation generated by electric fans should be measured by controllers. The amount of fuel as well as the amount of initial air is done by equipment called dampers and cams connected to the lever, which must be well sensitive to changes in these cases.