Six Methods to Prevent Blockage and Jamming of Regulating Valves
Self-operated regulating valves are prone to blockage and jamming during daily operation, which will degrade valve performance. Below are six effective methods to avoid blockage and jamming of self-operated regulating valves.
1. Cleaning Method
Welding slag, rust and debris inside pipelines may cause blockage or jamming at the throttling orifice, guiding parts and balance holes of the lower valve cover, resulting in scratches and scuffing on the curved surface of the valve plug and guiding surfaces.
When this problem occurs, disassemble the valve for thorough cleaning and remove all debris. Grind the sealing surface if it is damaged. Meanwhile, open the bottom plug to flush out foreign matter falling into the lower valve cover through balance holes, and flush the entire pipeline. Before commissioning, fully open the regulating valve and let the medium circulate for a period of time before putting it into normal service.
2. Medium Scouring Method
This method utilizes the scouring energy of the process medium itself to wash away easily precipitated and blocking substances, improving the anti-blocking performance of the valve. Common measures include:
a. Adopt flow-to-close installation;
b. Use streamline valve body;
c. Arrange the throttling orifice at the position subjected to the strongest medium scouring. When applying this measure, it is necessary to improve the erosion resistance of throttling components.
3. Convert Straight-through Type to Angle Type
Straight-through valves feature an inverted S-shaped flow path with complicated flow channels and large dead zones in upper and lower cavities, which facilitates medium deposition.
For angle-type connection, the medium flows similar to passing through a 90° elbow. It delivers favorable scouring performance with fewer dead zones and can be easily designed into a streamline configuration.
4. Increase Throttling Clearance Method
Solid particles in the medium, welding slag and rust washed off from pipelines may get stuck at the throttling orifice and trigger blockage or jamming. The problem can be solved by adopting throttling components with larger throttling clearance, such as slotted valve plugs and sleeves with concentrated throttling area instead of circumferentially distributed openings.
For single-seat and double-seat valves, the plunger-type valve plug can be replaced with a V-notched valve plug, or the valve can be modified into a sleeve valve.
5. External Flushing Method
Conventional regulating valves are often blocked at throttling orifices and guiding sections when handling easily precipitated medium containing solid particles. Flush gas or steam can be connected externally at the bottom plug of the lower valve cover.
If the regulating valve becomes blocked or jammed, open the external gas or steam valve to complete online flushing without removing the regulating valve and restore normal operation.
6. Install Pipeline Filter
Small-bore regulating valves, especially ultra-low flow regulating valves, have extremely narrow throttling clearance. Tiny debris in the medium can easily cause blockage. It is recommended to install a filter on the upstream pipeline of the valve to guarantee smooth medium flow.
For regulating valves equipped with positioners, blockage of throttling orifices in the air circuit is the most frequent fault leading to abnormal positioner operation.
1. Cleaning Method
Welding slag, rust and debris inside pipelines may cause blockage or jamming at the throttling orifice, guiding parts and balance holes of the lower valve cover, resulting in scratches and scuffing on the curved surface of the valve plug and guiding surfaces.
When this problem occurs, disassemble the valve for thorough cleaning and remove all debris. Grind the sealing surface if it is damaged. Meanwhile, open the bottom plug to flush out foreign matter falling into the lower valve cover through balance holes, and flush the entire pipeline. Before commissioning, fully open the regulating valve and let the medium circulate for a period of time before putting it into normal service.
2. Medium Scouring Method
This method utilizes the scouring energy of the process medium itself to wash away easily precipitated and blocking substances, improving the anti-blocking performance of the valve. Common measures include:
a. Adopt flow-to-close installation;
b. Use streamline valve body;
c. Arrange the throttling orifice at the position subjected to the strongest medium scouring. When applying this measure, it is necessary to improve the erosion resistance of throttling components.
3. Convert Straight-through Type to Angle Type
Straight-through valves feature an inverted S-shaped flow path with complicated flow channels and large dead zones in upper and lower cavities, which facilitates medium deposition.
For angle-type connection, the medium flows similar to passing through a 90° elbow. It delivers favorable scouring performance with fewer dead zones and can be easily designed into a streamline configuration.
4. Increase Throttling Clearance Method
Solid particles in the medium, welding slag and rust washed off from pipelines may get stuck at the throttling orifice and trigger blockage or jamming. The problem can be solved by adopting throttling components with larger throttling clearance, such as slotted valve plugs and sleeves with concentrated throttling area instead of circumferentially distributed openings.
For single-seat and double-seat valves, the plunger-type valve plug can be replaced with a V-notched valve plug, or the valve can be modified into a sleeve valve.
5. External Flushing Method
Conventional regulating valves are often blocked at throttling orifices and guiding sections when handling easily precipitated medium containing solid particles. Flush gas or steam can be connected externally at the bottom plug of the lower valve cover.
If the regulating valve becomes blocked or jammed, open the external gas or steam valve to complete online flushing without removing the regulating valve and restore normal operation.
6. Install Pipeline Filter
Small-bore regulating valves, especially ultra-low flow regulating valves, have extremely narrow throttling clearance. Tiny debris in the medium can easily cause blockage. It is recommended to install a filter on the upstream pipeline of the valve to guarantee smooth medium flow.
For regulating valves equipped with positioners, blockage of throttling orifices in the air circuit is the most frequent fault leading to abnormal positioner operation.
