Common faults of medium and high pressure valves and their solutions?

Medium and high pressure valves are often used to withstand high pressure and temperature, and are widely used in the fields of petroleum, chemical industry, and electric power. Due to its complex working environment, valves may have various faults during long-term use. The following are common faults of medium and high pressure valves and their solutions:

1. Valve leakage
Valve leakage is one of the most common problems of medium and high pressure valves, which may occur at the valve seat, sealing surface, valve stem, flange and other connection parts.
Common causes:
Sealing surface wear or aging.
Damage to seals (such as O-rings, gaskets, soft seals, etc.).
The valve has not been maintained or inspected for a long time.
Improper operation or overload operation leads to poor contact of the sealing surface.
Solution:
Check the seals: Regularly check and replace worn or aged seals (such as O-rings, sealing gaskets, sealing rings, etc.) to ensure good sealing effect.
Reprocess the sealing surface: Grind, polish or reprocess the sealing surface of the valve to ensure that the sealing surface is flat and smooth to avoid leakage due to poor sealing.
Adjust the valve seat pressure: For some valves (such as ball valves, butterfly valves, etc.), the sealing is increased by adjusting the pressure of the valve seat or sealing surface.
Check flanges and threaded joints: Make sure there is no looseness or cracks in flanges and threaded joints, and tighten the connecting parts in time.

2. Valve jam or failure
Valve jam or failure usually occurs during the movement of valve core, valve stem and other parts, causing the valve to fail to open and close normally, or even fail to operate.
Common causes:
Valve stem rust or surface damage.
Dirt and impurities on the sealing surface.
Long-term non-use causes adhesion or freezing of internal valve parts.
Frequent operation causes excessive wear of parts.
Actuator failure or insufficient air source (for pneumatic or electric valves).
Solution:
Cleaning the inside of the valve: Regularly clean the impurities in the valve, especially the particles between the valve seat and the valve core, to avoid jamming.
Lubricate the valve stem and moving parts: Regularly add lubricating oil to the moving parts such as the valve stem, valve seat, and sealing surface to prevent friction damage and jamming.
Check the actuator: Check the pneumatic, hydraulic or electric actuator to ensure that the air source and power supply are normal and the actuator moves flexibly.
Replace worn parts: When the valve core, valve stem or other moving parts of the valve are severely worn, they should be replaced in time.

3. The valve cannot be completely closed or opened
The failure of the valve to be completely closed or opened usually causes medium leakage, affecting the normal operation of the system. For the regulating valve, the failure to be completely opened or closed will lead to inaccurate flow and pressure control.
Common causes:
Foreign matter or wear on the valve seat or sealing surface.
The actuator fails, resulting in insufficient driving force.
The seal is aged or damaged, resulting in the inability of the valve to be completely sealed.
The valve positioning mechanism fails, resulting in the valve not moving in place.
Solution:
Check the sealing surface and valve seat: remove foreign matter, dirt or corrosion on the sealing surface, and reprocess the sealing surface to ensure that the valve is completely closed or opened.
Check the valve positioning device: If the valve has a positioning mechanism, check whether the positioning device is damaged or loose, and adjust or replace it if necessary.
Check the actuator: Make sure that the actuator can provide sufficient power and accurate positioning signals. Check whether the air source (for pneumatic valves) or power supply (for electric valves) is stable and whether the actuator is working properly.
Replace damaged seals: Check soft seals and other sealing components. If any damage is found, replace them in time.

4. Valve vibration or noise
The valve may generate vibration or noise during operation, which will affect the stability of the system and even damage the valve and surrounding equipment.
Common causes:
The valve is frequently opened and closed, resulting in a sharp change in fluid flow rate and vibration.
There is uneven flow distribution or pressure fluctuation in the pipeline system.
When the valve is working, the internal fluid velocity is too high or turbulence is generated.
The actuator is not driven smoothly or improperly operated.
Solution:
Flow regulation: Avoid frequent opening and closing of the valve, and use slow start and closing to reduce drastic changes in fluid flow rate.
Optimize pipeline design: Check whether the pipeline design is reasonable, ensure smooth fluid flow, and avoid local fluctuations or turbulence in the pipeline.
Check the switching frequency of the valve: For valves that are frequently opened and closed, you can consider installing a vibration reduction device to reduce the impact of vibration on the valve.
Adjust the actuator: Check the driving stability of the actuator to ensure that it can smoothly control the opening and closing of the valve.

5. Valve corrosion
Under some special working conditions, the valve may be exposed to corrosive media, resulting in corrosion damage to the valve, which in turn affects its normal operation.
Common causes:
The medium itself is corrosive, such as acidic or alkaline media.
Improper selection of valve materials cannot effectively resist corrosion.
Failure of valve surface coating or anti-corrosion treatment.
Solution:
Use corrosion-resistant materials: Select materials with strong corrosion resistance, such as stainless steel, alloy steel, etc., or select suitable alloy materials according to the corrosiveness of the medium.
Apply anti-corrosion coating: Apply anti-corrosion coating to the outer surface of the valve (such as polytetrafluoroethylene coating, epoxy resin coating, etc.) to enhance corrosion resistance.
Install filter device: Install a filter or isolation device in front of the valve to reduce the impact of corrosive particles on the valve.
Check corrosion regularly: Check the corrosion of the valve surface regularly, and clean and re-coat the surface when necessary.

6. Actuator failure
The actuator is an important component of medium and high pressure valves. Common pneumatic and electric actuator failures will cause the valve to fail to open or close as required.
Common causes:
Power supply problem (electric actuator).
Air source problem (pneumatic actuator).
Actuator control signal is lost or distorted.
Actuator mechanical failure, such as worn or damaged transmission parts.
Solution:
Check electrical connection or air source: Make sure the power supply of electric actuator is normal and the air source pressure of pneumatic actuator is stable. Check whether the air source pipeline and electrical line are unobstructed.
Check control signal: Check whether the signal output of the control system is normal to ensure that the actuator can receive the correct control signal.
Replace damaged parts: Check whether the transmission parts (such as gears, motors, etc.) inside the actuator are worn or damaged, and replace parts if necessary.
Maintain the actuator regularly: Check and maintain the actuator regularly, including lubrication, cleaning and calibration.