1. Cleaning method
Welding slag, rust, slag, etc. in the pipeline cause blockage or jamming in the throttle, guide part, and balance hole of the lower valve cover, causing strain and scratches on the valve core curved surface and guide surface, and indentation on the sealing surface. This often occurs in the initial operation of new systems and after overhaul. This is the most common fault. In this case, it must be removed for cleaning to remove the slag. If the sealing surface is damaged, it should be ground; at the same time, the bottom plug should be opened to flush out the slag that falls from the balance hole into the lower valve cover, and the pipeline should be flushed. Before commissioning, let the regulating valve fully open, and the medium flow for a period of time before it is put into normal operation.
2. External flushing method
When ordinary valves are used to adjust some media that are easy to precipitate and contain solid particles, they are often blocked at the throttle and guide. Flushing gas and steam can be connected externally at the bottom plug of the lower valve cover. When the valve is blocked or stuck, open the external gas or steam valve to complete the flushing work without moving the regulating valve, so that the valve can operate normally.
3. Install pipeline filter method
For small-diameter regulating valves, especially ultra-small flow regulating valves, the throttling gap is very small, and there cannot be a little slag in the medium. In case of blockage in this case, it is best to install a filter on the pipeline in front of the valve to ensure the smooth passage of the medium. For regulating valves used with positioners, the positioner does not work properly and the blockage of the gas path throttling port is the most common fault. Therefore, when working with a positioner, the gas source must be handled properly. The usual method is to install an air filter pressure reducing valve on the gas source pipeline in front of the positioner
4. Increase the throttling gap method
If the solid particles in the medium or the welding slag and rust washed away in the pipeline cannot pass through the throttling port and cause blockage, jamming and other faults, a throttling piece with a large throttling gap can be used instead-the throttling area is a window-opening, opening type valve core, sleeve, because its throttling area is concentrated rather than circumferentially distributed, the fault can be easily eliminated. If it is a single or double seat valve, the plunger valve core can be changed to a "V" shaped valve core, or changed to a sleeve valve, etc. For example, a chemical plant has a double seat valve that often gets stuck. After it is recommended to use a sleeve valve, the problem is immediately solved.
5. Medium flushing method
Use the flushing energy of the medium itself to flush and take away things that are easy to precipitate and clog, thereby improving the anti-blocking function of the valve. Common methods are: ① Change to flow-closed type; ② Use a streamlined valve body; ③ Place the throttle port at the most severe flushing point. When using this method, pay attention to improving the erosion resistance of the throttling material.
6. Straight-through to angle method
Straight-through is an inverted S flow, with a complex flow path and many dead zones in the upper and lower cavities, which provides a place for the precipitation of the medium. Angle connection, the medium is like flowing through a 90° elbow, with good flushing performance, small dead zone, and easy to design into a streamlined shape. Therefore, when a straight-through regulating valve is slightly blocked, it can be changed to an angle valve.