Treatment methods of blockage of globe control valve

Treatment methods of frequent blockage of globe control valve

The globe control valve is often stuck or blocked in use. The following solutions are given:

1. Cleaning method of globe control valve

Welding slag, rust and slag in the pipeline cause blockage or jamming in the orifice, guide part and balance hole of the lower bonnet, resulting in strain and scratch on the valve core surface and guide surface, indentation on the sealing surface, etc. This often occurs in the initial stage of new system operation and operation after overhaul. This is the most common fault. In this case, it must be removed for cleaning and slag removal. If the sealing surface is damaged, it shall also be ground; At the same time, open the bottom plug to flush the slag falling into the lower valve cover from the balance hole and flush the pipeline. Before putting into operation, fully open the regulating valve and bring the medium into normal operation after flowing for a period of time.

2. External scouring method of globe control valve

When ordinary valves are used to regulate some media that are easy to precipitate and contain solid particles, they are often blocked at the throttle and guide, and scouring gas and steam can be connected outside 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 and make the valve operate normally.

3. Installation of pipeline filter of globe control valve

For small-diameter control valves, especially ultra-small flow control valves, the throttling clearance is very small, and there shall be no 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. For the regulating valve with positioner, the positioner does not work normally, and the blockage of its gas path throttle is the most common fault. Therefore, when working with the positioner, the air source must be handled properly. The usual method is to install an air filtration pressure reducing valve on the air source pipeline in front of the positioner

4. Increase throttle clearance method of globe control valve

For example, the solid particles in the medium or the washed out welding slag and rust in the pipeline can not pass through the orifice, resulting in blockage, jamming and other faults, the throttling parts with large throttling clearance can be used - the valve core and sleeve with window and opening throttling area can be used. Because the throttling area is concentrated rather than circular distribution, the fault can be easily eliminated. If it is a single or double seat valve, the plunger valve core can be changed into a valve core with "V" port, or into a sleeve valve, etc. For example, a two seat valve in a chemical plant is often stuck. It is recommended to use sleeve valve, and the problem will be solved immediately.

5. Medium scouring method of globe control valve

Use the scouring energy of the medium itself to scour and take away things that are easy to precipitate and block, so as to improve the anti blocking function of the valve. The common methods are: ① change to flow closed type; ② Streamline valve body is adopted; ③ Place the throttle at the place where the erosion is most severe, and pay attention to improving the erosion resistance of the throttle material.

6. Straight through method is changed to angular method of globe control valve

The direct flow is inverted s flow, the flow path is complex, and there are many dead zones in the upper and lower cavities, which provides a place for medium precipitation. Angular connection, the medium is like flowing through a 90 ℃ elbow, with good scouring performance, small dead zone and easy to design into flow line. Therefore, the use of straight through control valve can be changed to angle valve when it is slightly blocked.