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01, cleaning method
The welding slag, rust, and residue in the pipeline cause blockage or jam in the throttle orifice, guide part, and balance hole of the lower valve cover, resulting in strain and scratch on the spool surface and guide surface, and indentation on the sealing surface. This often occurs in the initial phase of operation after a new system is put into operation and a major overhaul. This is the most common failure.
In this case, it must be removed for cleaning, remove the slag, such as the sealing surface is damaged should also be ground; At the same time, the bottom plug is opened to wash away the slag falling into the lower valve cover from the balance hole and wash the pipeline. Before putting into operation, let the regulating valve be fully open, and the medium flow for a period of time before normal operation.


02, the external flushing method for some easy to precipitate, containing solid particles of the medium with ordinary valve regulation, often in the throttle, guide blocked, can be under the valve cover at the bottom plug external flushing gas and steam.
When the valve is blocked or stuck, open the external gas or steam valve, you can complete the flushing work without moving the regulating valve, so that the valve can operate normally.


03, install pipeline filter method
For small-caliber regulating valves, especially ultra-small flow regulating valves, the throttle gap is extremely small, and there can be no little slag in the medium.
In case of blockage, it is best to install a filter on the pipeline in front of the valve to ensure the smooth passage of the medium.
With the regulator used by the positioner, the positioner does not work properly, and the blockage of the gas path orifice is the most common fault.
Therefore, when working with a positioner, it is necessary to deal with the air source, and the usual method is to install an air filter pressure reducing valve on the air source pipeline before the positioner.


04, increase the throttle gap method
If the solid particles in the medium or the welding slag and rust washed away in the pipeline can not pass the throttle and cause blockage, jamming and other faults, you can use the throttle part with a large throttle gap - the throttle area is the valve core and sleeve of the opening window and the opening class, because the throttle area is concentrated rather than circular distribution, the fault can be easily eliminated.
If it is a single or two-seat valve, the plunger spool can be changed to a "V" spool, or a sleeve valve.
For example, a chemical plant has a two-seat valve that is often stuck, and it is recommended to use a sleeve valve to solve the problem immediately.


05, medium flushing method
Use the scouring energy of the medium itself to wash and take away things that are easy to precipitate and clog, so as to improve the anti-blocking function of the valve.
Common methods are:
Change to flow closed use;
Adopting streamlined valve body;
The throttling is placed in the most severe scouring place, and the erosion resistance of the throttling material should be improved by using this method.


06, through to the corner method
The direct flow is inverted S flow, the flow path is complex, and the dead zone of the upper and lower cavity is many, which provides a place for the precipitation of the medium. Angle connection, the medium is like flowing through 90℃ elbow, good scouring performance, small dead zone, easy to design into a flow line. Therefore, the use of straight-through regulating valves can be changed to Angle valves when slight blockage occurs.