Selection principle and maintenance of control valve
3. Maintenance of the control valve The control valve has the characteristics of simple structure and reliable action, but because it is in direct contact with the process medium, its performance directly affects the quality of the system and environmental pollution, so the control valve
must be regularly maintained and repaired. In harsh and important occasions, more attention should be paid to maintenance work.
Key inspection sites
(1) The inner wall of the valve, for the control valve
used in high pressure difference and corrosive media, the inner wall of the valve and the diaphragm of the diaphragm valve are often impacted and corroded by the medium, and the pressure and corrosion resistance must be checked.
(2) When the valve seat and control valve are working, due to the infiltration of the medium, the inner surface of the thread used for fixing the valve seat is easily corroded and the valve seat is loosened. Pay attention when checking. For valves that work under high pressure difference, it is also necessary to check whether the sealing surface of the valve seat is damaged.
(3) The spool, the spool is the movable part during the adjustment work, and is most seriously eroded and corroded by the medium. During maintenance, carefully check whether the various parts of the spool are corroded and worn, especially in the case of high pressure difference. Core wear is more severe (due to cavitation) and should be noted. When the valve core is seriously damaged, it should be replaced. In addition, attention should be paid to whether the valve stem also has a similar phenomenon, or the connection with the valve core is loose.
(4) Diaphragm "O" rings and other gaskets. The diaphragm and "O"-shaped gasket in the control valve
should be checked for aging and cracking.
(5) Sealing packing: Pay attention to whether the polytetrafluoroethylene packing and sealing grease are aging, and whether the mating surface is damaged, and should be replaced when necessary.