Features of high pressure boiler tubes
The steel pipe used for the boiler should have the following characteristics: steel pipes used for boilers should have sufficient durable strength and plastic deformation ability, minimum aging tendency and hot brittleness, good resistance to oxidation, coal ash, corrosion resistance at high temperatures in natural gas and steam, stress corrosion resistance, good organizational stability and process performance.The material of the high-pressure boiler tube will creep because it works under high temperature and high pressure for a long time, resulting in a decline in plasticity and toughness, change of the original structure and corrosion.
Tubes used for heating surfaces of low and medium pressure boilers should have normally working pressure not more than 5.88Mpa and working temperatures below 450℃. Tubes used for heating surfaces of high-pressure boilers, economizers, superheaters, reheaters, petrochemical industry, etc. should have normally working pressure above 9.8Mpa and working temperature between 450℃ and 650℃.
The steel types of high pressure boiler tubes include carbon steel, pearlite, ferrite and heat resistant austenitic stainless steel. In order to improve the thermal efficiency of thermal power generating units and reduce fuel consumption, countries all over the world have developed thermal power units with 1000MW, large capacity and high parameters at high temperature and pressure. The steam pressure has increased to 31.5 to 34.3MPa, and the superheated steam temperature has reached 595 to 650℃, which expand to the ultra-high pressure critical pressure.