未标题 8

Fault analysis and treatment method of regulating valve

Fault analysis and treatment method of regulating valve shared by JIS Marine valve Manufacturer.

Regulating valve has been widely used in industrial control. It is of great significance to ensure the normal operation and safe production of the process unit. Therefore, it is necessary to strengthen the maintenance of the regulating valve. As a common regulating unit, the problems in the use of the valve will bring adverse effects to production, so it is very important to deal with the problems in the use of the valve in time. In this paper, some faults and treatment methods of regulating valve are analyzed. Below the diaphragm film head type actuator and cylinder type actuator are respectively analyzed.

Diaphragm head actuator

1. The level control valve is out of control and cannot be opened

Liquid level measurement indicator has been very high, regulator output is also very large, but the regulating valve can not be opened, had to play a mechanical hand wheel control. Check the valve positioner (remove the connection pipe of the film head and plug it), press the nozzle baffle mechanism, no change in the output of the positioner, check that the throttle hole is unobstructed, disassemble the amplifier and find that the diaphragm of the amplifier is broken. Replace the diaphragm and reset the regulating valve automatically. Valve positioner amplifier diaphragm broken, back pressure chamber no back pressure, amplifier no output, so the control valve out of control.

2. Valve positioner feedback slide rod rust dead

The liquid level fluctuates severely, the inspection finds that the slide rod of valve positioner feedback mechanism is completely rusted and cannot rotate, so the valve has to be controlled by hand wheel. Try to knock out the slide bar, rusting and refueling after loading, regulating valve back to normal. Valve positioner feedback mechanism, with the valve opening size change and add the corresponding amount of feedback positioner. Slide bar rust dead, feedback force can not change with the size of the valve opening, and can not make the valve opening stop in the corresponding position of the regulator output signal, resulting in liquid level fluctuation.

3. The pressure control valve cannot operate

A process load reduction, the amount of natural gas can not be reduced, is the natural gas pressure regulation valve can not operate. The output signal of the valve was found to be normal during the inspection. It is estimated that the valve core was carbon stuck. After that, the valve was closed by increasing the pneumatic signal and adding the force of the hand wheel. When the valve is disassembled for inspection, it is not surprising that the valve has few load stability switches, and the carbon black in the natural gas gets stuck in the small gap between the stem and the guide sleeve. Therefore, after the annual overhaul, the valve will be taken apart to clean, to avoid similar accidents.

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