How to eliminate common faults of control valves?

The normal operation of the control valve has a great relationship with the maintenance work of the control valve. There are many kinds of failures of regulating control valves, and a certain kind of failure may also have different reasons. Let's learn about common faults and elimination methods of control valves together.

 

 

The main faulty components of the actuator

Pneumatic actuator and hydraulic actuator

1. Diaphragm. For membrane pneumatic actuators, the diaphragm is the most important element. Under the normal condition of the air supply system, if the actuator does not move, it should be considered whether the diaphragm is broken or not installed properly. When the surface of the metal contact surface has sharp corners, burrs and other defects, the diaphragm will be punctured, and the diaphragm must not leak. In addition, if the diaphragm is used for too long, the aging of the material will also affect the use.

 

2. Piston. The pistons of pneumatic actuators and hydraulic actuators generate driving force, so the damage and wear of the pistons are absolutely not allowed.

 

3. Gas (liquid) pipe. This is the path through which the input pressure leads to the actuator, so it is necessary to check whether it is connected firmly and does not leak.

 

4. Putting. Check whether the push rod is bent, deformed, or dropped off. The push rod and the valve rod must be firmly connected and the position must be adjusted to ensure sufficient stroke and close the valve.

 

5. Spring. Check whether the spring is broken. Improper manufacturing, processing, and heat treatment will cause the spring to break. Some springs may also break under excessive load.

 

Electric actuator

1. Motor. Check whether the motor can rotate, whether it is easy to overheat, whether there is sufficient torque and coupling force.

2. Servo amplifier. Check whether there is output and whether it can be adjusted.

3. Speed reduction mechanism. The reduction mechanism of each manufacturer is different. Therefore, check whether the transmission parts—shafts, gears, worm gears, etc.—are damaged or worn out.

4. Torque controller. Check the cause of failure according to the specific structure.

 

 

The main fault components of the valve

1. Valve body. It is necessary to frequently check the corrosion and wear of the inner wall of the electric control valves and electric actuator valves, especially the valve used in corrosive media, high pressure difference, cavitation and other harsh process conditions, and its compressive strength, corrosion resistance and wear resistance must be guaranteed.

 

2. Valve core. Because the valve core plays the role of regulating and cutting off the fluid, it is a movable shut-off element, so it is most important to be affected by the erosion, corrosion, and particle collision of the medium. It is more likely to be damaged under high pressure difference and cavitation. To check whether its parts are damaged, worn, corroded, whether to repair or replace.

 

3. Valve seat. The valve seat joint surface is the key to ensure the valve is closed, and its corrosion and wear are also serious. Moreover, due to the penetration of the medium, the threaded inner surface of the fixed valve seat is often corroded and loosened. This part should be specially checked.

 

4. Valve stem. Check whether the connection between the valve stem and the valve core and push rod is loose, and whether there is excessive deformation, cracks and corrosion.