Internal leakage problem in cage-type control valves
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Our unit (for boiler feed water and steam) uses several cage-type control valves that are experiencing internal leakage and sticking problems; how can these be resolved?
Generally, it is only possible to open the valve during shutdown for maintenance in order to determine the cause of internal leakage. The reason for the jamming could be something stuck inside the pipeline, obstructing the throttle component and causing the jam. Internal leakage is a common phenomenon in valves that have been in use for some time; if the wear on the sealing surfaces is not severe, attempts can be made to repair them. However, if there are deep dents or damage, it is necessary to replace them with matching spare parts.
Commonly, it is caused by the pipes not being cleaned thoroughly during installation, with debris such as welding slag getting stuck or wearing out the sealing surfaces.
The valve can only be opened for cleaning, and the valve core must be removed, as certain foreign objects may get stuck in the valve cage； For internal leakage, it is necessary to determine whether it is due to issues with the stroke or some damage; in cases of severe damage, the components must be replaced or the valve itself needs to be replaced.