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How to deal with the jam or blockage of the regulating valve

September 23, 2020

Regulating valves are often referred to as control valves. It accepts the control signal output from the adjustment control unit in the area of industrial automation process control and uses power operation to alter the final control element of process parameters such as medium flow, pressure, temperature, and liquid level. It normally consists of a drive actuator and a valve. The control valve can be classified into straight stroke and angular stroke according to the characteristics of the stroke; it can be divided into three forms according to the power used by the actuator: pneumatic control valve, electric control valve, and hydraulic control valve depending on their functions and characteristics. There are three types of linear characteristics, the same percentage characteristics, and the parabolic characteristics. The air, water, steam, various corrosive media, dirt, oil, and other media for these regulating valves are suitable.


Effective treatment can ensure that the valve plays a good control role in the control system to regulate the installation of valves, despite certain issues that often occur during use. Particularly for the method of treatment where the valve is often stuck or blocked.

1.      Cleaning:

The pipeline’s total welding slag, rust, slag, etc. cause blockage or jam in the orifice, guide component, and lower valve cover balance hole, causing strain and scratches on the core surface and guide surface of the valve, and wait sealing surface indentation. This also happens in the initial commissioning and during substantial repairs of new systems. It’s the most common failure. If the sealing surface is impaired, it should be grounded; to wash away the slag transferred from the balance hole into the lower valve cover, the colleague will open the bottom plug and perform flushing. Let the controlling valve be completely opened before bringing it into operation, and the medium will flow for some time before being placed into regular operation. 

2.      External flushing:

The orifice and guide are often blocked when ordinary valves are used to modify such media that are easy to precipitate and contain solid particles. It is possible to attach the flushing gas and steam to the lower valve cover’s bottom plug. If the valve is blocked or stuck, open the external gas or steam valve without moving the controlling valve to complete the flushing work and make the valve working normally.

3.      Install pipe filter:

The throttle gap is extremely small for small diameter control valves, especially the ultra-small flow control valves, and there should be no slag in the medium. To ensure the smooth flow of the medium, it is best to mount a strainer on the pipe before the valve in the condition of a blockage. The positioners do not operate properly when controlling valves with positioners, and the most common fault is the air passage orifice blockage. The air source must, therefore, be treated while operating with a positioner. The normal approach is to mount an air filter pressure relief valve in front of the positioner on the air source side

4.     Increase the throttle gap:

Because of the orifice failure, the solid particles in the medium or the welding slag and rust that are washed away from the pipeline cause blockage, jamming, and other faults. The throttle area is available, and you can turn to throttle with a wide throttle gap. The fault can be easily removed by the valve cores and sleeves, such as windows and openings since their throttling region is centered rather than scattered on the circumference. The plunger valve core may be modified to a “V” shaped valve core, or a sleeve valve, whether it is a single or double seating valve. For example, a double-sitting valve is sometimes stuck in a chemical plant. Switching to a sleeve valve is advised, and the issue is fixed immediately.

5.      Media erosion process:

Using energy flushing medium itself, and quickly precipitate washed away, something easy to block, preventing the valve from improving the blocking role. Popular ways are to:

  • Change to flow-closed use;
  • Use streamlined valve body;
  • Set the orifice at the most extreme scoured location. In this system, care should be taken to increase the resistance of the throttle material to erosion.

6.      The straight body is changed to angle type:    

The straight flow is S flow reversed, the flow direction is complicated, and there are several dead areas in the upper and lower chambers that provide a place for the medium to precipitate. Angular connector, if flowing via the medium. 9 0 [deg.] Bend, strong erosion properties, a small dead area, easily streamlined to construct. Hence where a slightly blocked straight-through controlling valve can be adjusted to an angle valve.

Summary:   

  Blockage and jams in regulating valves will lead to many problems, which in turn reduce the overall efficiency of the system where the valve is fitted, this improper functioning of the valve can be controlled by the different measures discussed above. Implementing these measures in the system where the regulating valve is used in the system will reduce maintenance frequency and cost, which will make the operation more efficient and cost-saving.

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