As we all know, control valves play an important role in daily life and production, and have been widely studied and developed in technological applications and product development. Control valves are control components in fluid transportation systems, with functions such as guiding, closing, regulating, throttling, preventing backflow, diverting or overflowing pressure relief, etc., and are used to control the movement of various types of fluids such as air, water, steam, various corrosive chemical media, mud, liquid metals, and radioactive substances.
Control valves have the characteristics of simple structure and reliable operation, but because they are directly in contact with the process medium, their performance directly affects the system quality and environmental pollution, so regular maintenance and periodic inspection must be carried out for control valves, especially for harsh and important conditions, more attention should be paid to maintenance work. The key inspection parts are as follows.
For control valves used in high pressure differential and corrosive medium applications, the inner wall of the valve body and the diaphragm of the diaphragm valve are often impacted and corroded by the medium, so it is necessary to focus on checking the pressure resistance and corrosion resistance.
During the operation of control valves, the fixed valve seat is easily corroded due to the infiltration of the medium, so attention should be paid to checking it. For valves operating under high pressure differential, the sealing surface of the valve seat should also be checked for damage.
The valve core is the movable part during adjustment work, and is most severely affected by the scouring and corrosion of the medium. During inspection, it is necessary to carefully check whether each part of the valve core is corroded or worn, especially when the valve core is severely worn under high pressure differential (due to cavitation), attention should be paid. When the control valve valve core is severely damaged, it should be replaced. In addition, attention should also be paid to whether the valve stem has similar phenomena or whether it is loose when connected to the valve core.
Check whether the diaphragm and O-ring seal of the control valve are aging or cracked.
Pay attention to whether the PTFE packing and sealing lubricating grease are aging, and whether the mating surface is damaged. Replace when necessary.
Regulating valves, also known as control valves, are the main types of actuators. By accepting the control signals output by the regulating control unit, the fluid flow rate can be changed through dynamic operation. Regulating valves generally consist of an actuator and a valve. If classified according to the power used by the associated actuator, regulating valves can be divided into three types: pneumatic, electric, and hydraulic, which are regulating valves powered by compressed air, electricity, and liquid media (such as oil), respectively. Moreover, according to their functions and characteristics, there are also electromagnetic valves, electronic-type, intelligent-type, fieldbus-type regulating valves, etc.