Application and characteristics of large diameter forged steel pneumatic ball valve the quality and performance of the valve body directly affect the service life and safety of the valve. Therefore, forged valve body shall be used in case of poor working environment or high requirements for safety. For gate valves, globe valves, check valves, etc. below DN50, most of them in China adopt the process of welding flanges at both ends after integral forging, and some manufacturers forge flanges together. For the valve body with a large diameter of more than 2 inches, due to the lack of heavy multi-directional forging equipment required for forging, it is still difficult to realize the large-scale integral forging parts made in China. Therefore, many manufacturers import large valve body forgings from abroad, or cooperate with some foreign enterprises to develop and use forged and welded valve body parts.

3. The pneumatic feed water regulating valve of the boiler is not well matched with the system, which is mainly manifested in that 1. The high feed water temperature is generally 102-104 ℃, which makes the temperature of the feed water regulating valve body higher, which is not conducive to the heat dissipation of the motor. The motor 2, which is very easy to burn out the pneumatic regulating valve, has a large pressure difference at both ends of the pneumatic feed water regulating valve. The outlet pressure depends on the steam pressure, and the pressure difference at both ends of the pneumatic feed water regulating valve is large, The output torque of the pneumatic actuator motor is large, so the feed water regulating valve will not be closed small at low load, causing unstable water level. 3 The time constant of the boiler drum level control parameter changes greatly at low load, and the system oscillation is prone to occur during the regulation process. Especially when the three impulse regulator is used for control, the time constant of the three parameters selected is very small, high-precision control and short cycle, If effective anti-interference measures are not taken, the feed water regulating valve rod will move up and down frequently, causing too fast friction and wear, and serious water leakage will occur at the seal.