1) Cleaning method

The welding slag, rust and slag in the pipeline cause blockage or blockage in the throttle orifice, the guide position and the balance hole of the lower valve cover, which results in the pull and scratch of the valve core surface, the guide surface and the indentation on the sealing surface. This often occurs in the early stages of operation after new operation systems and major repairs. This is the most common failure. In this case, it is necessary to unload and clean, remove slag, if the sealing surface is damaged, it should be grinded; at the same time, the bottom plug should be opened to wash away the slag falling from the balance hole into the lower valve cover, and flush the pipeline. Before putting into operation, let the control valve be fully opened and the medium flow for a period of time before it is brought into normal operation.

2) External scouring method

When the ordinary valve is used to regulate the medium which is easy to precipitate and contains solid particles, it is often blocked at the throttle and guide, and the gas and steam can be washed out at the bottom plug of the lower valve cover. When the valve is blocked or stuck, open the external gas or steam valve, which can complete the flushing work without the control valve, and make the valve run normally.

3) Installation of Pipeline Filter Method

For small caliber control valves, especially ultra-small flow control valves, the throttle clearance is very small, and there can be no residue in the medium. In case of blockage, it is better to install a filter on the pipe in front of the valve to ensure the smooth passage of the medium. The control valve with positioner works abnormally, and the blockage of the throttle is the most common fault. Therefore, when working with positioner, it is necessary to deal with the air source. The usual method is to install air filter pressure relief valve on the gas source pipeline in front of positioner.

4) Increasing Throttle Gap Method

For example, solder particles in the medium or solder slag and rust washed out in the pipeline can not pass through the throttle and cause blockage and blockage. The throttle with large throttle clearance can be replaced by the valve core and sleeve with open window and opening type. Because the throttle area is concentrated rather than circularly distributed, the fault can be easily eliminated. If it is a single or double seat valve, the plunger-shaped spool can be changed into a "V" shaped spool, or into a sleeve valve, etc. For example, in a chemical plant, a double-seat valve is often jammed. When the sleeve valve is recommended, the problem will be solved immediately.

5) medium scouring method

By utilizing the scouring energy of the medium itself, it can scour and take away the things that are easy to precipitate and clog, thus improving the anti-blocking function of the valve. Common methods are as follows: 1) changing to flow-closed type; 2) adopting streamlined valve body; 3) placing the throttle port in the most severe scouring place; using this method, attention should be paid to improving the erosion resistance of throttle material.

6) Change Straight Pass to Angle Method

Direct flow is backward S flow, the flow path is complex, and there are many dead zones in upper and lower chambers, which provides a place for the precipitation of medium. Angular connection, medium like flow through 90 elbows, good scouring performance, small dead zone, easy to design into streamlined. Therefore, when slight blockage occurs by using a through regulating valve, it can be changed into an angular valve to make the temperature rise.

7) Increase the gap

Sleeve control valves used in steam pipelines, if the clearance between the spool and sleeve is too small, or different materials are used, are likely to be blocked due to different expansion coefficients. In order to prevent similar situation, the gap can be enlarged appropriately during processing (on the premise of meeting the flow control requirements).