Valves are crucial devices in fluid control systems, primarily controlling fluid flow through functions such as switching, flow regulation, and check valves. With the increasing complexity of industrial equipment, valve malfunctions have become a significant factor affecting system stability and safety. Valve failures not only disrupt normal equipment operation but can also lead to safety accidents such as leaks and pipeline ruptures. Therefore, understanding common valve malfunctions and their solutions is essential knowledge for maintenance personnel.

I. Common Valve Failure Types
During long-term operation, valves may experience various types of malfunctions due to multiple factors. The following are some of the most common valve malfunctions encountered during use:

1. Water or Air Leakage
Causes: Water or air leakage is the most common valve malfunction, typically occurring at the valve's sealing points. Problems with the valve's sealing surfaces, sealing materials, or sealing structure can lead to fluid leakage. Specific causes may include:
Damaged Sealing Surfaces: Wear or corrosion on the valve's sealing surfaces (such as the contact surfaces between the gate and valve seat, or between the ball and the sealing seat).
Aging or Damaged Sealing Materials: Over time, sealing materials such as rubber and PTFE used in valves may age, crack, or deform, resulting in poor sealing. Improper Installation: During valve installation, misalignment of the sealing surfaces or incorrect placement of the sealing material can lead to water or air leaks.
Solutions:
Inspect the Sealing Surface:Regularly inspect the valve's sealing surfaces. If significant wear or corrosion is found, repair or replace them promptly.
Replace the Sealing Material:Replace aged or damaged sealing materials promptly, such as O-rings and valve seat sealing rings.
Check the Installation Method:Ensure the valve is installed according to specifications, especially ensuring the sealing surfaces are level to prevent leaks caused by improper installation.
Clean the Valve:Remove impurities and deposits from inside the valve, ensuring the sealing surfaces are not worn or contaminated.

2. Valve Cannot Fully Open or Close
Causes:A valve's inability to fully open or close is usually related to a faulty operating mechanism or structural malfunction of the valve itself. Common causes include:
Insufficient Operating Torque:Insufficient force from the handwheel, pneumatic, or electric drive unit to overcome the valve's opening and closing resistance.
Valve Blockage:The valve may be blocked by the accumulation of impurities, corrosion, or deposits, preventing smooth opening and closing.
Damaged or deformed sealing surfaces: Poor fit between the valve disc, butterfly plate, and other opening/closing components and the sealing surfaces prevents the valve from closing completely.
Drive unit malfunction: For pneumatic or electric valves, a malfunctioning drive unit (such as a damaged motor or insufficient air supply) can also cause the valve to malfunction.
Solutions:
Check the drive unit: For manual valves, check the handwheel and transmission components for proper function; for electric or pneumatic valves, check the motor, cylinder, or solenoid valve for proper operation.
Clear blockages: Regularly inspect the valve interior and clean out impurities, especially when handling media containing solid particles, to ensure the valve does not jam due to deposits.
Check sealing surfaces and opening/closing components: Check the valve disc, ball, and other opening/closing components for wear or damage, and repair or replace them promptly.
Increase operating torque: If the operating torque is insufficient, it may be necessary to replace the drive unit with a more powerful one or adjust the operating method to overcome the opening and closing resistance.

3. Valve Sticking or Inability to Rotate Smoothly
Causes: Valve sticking or inability to rotate is usually due to friction, corrosion, or scale buildup between the valve's opening and closing parts and the valve seat. Common causes include:
Poor Lubrication: Insufficient lubrication of the valve's moving parts can lead to increased friction and sticking.
Corrosion or Scale: Especially in the chemical and food industries, corrosive substances or deposits may accumulate inside the valve, causing it to operate inflexibly.
Valve Damage: Damage to the internal structure of the valve body can prevent the opening and closing parts from moving properly.
Solutions:
Regular Lubrication: Ensure that the valve's moving parts (such as the valve stem and valve disc) are adequately lubricated, using a suitable lubricant to reduce friction.
Check for Corrosion: If corrosion or scale is present inside the valve, clean it with specialized tools and replace severely corroded parts as needed.
Use Corrosion-Resistant Materials: In corrosive environments, valves made of corrosion-resistant materials should be selected, or the valves should be regularly treated with anti-corrosion measures.

4. Excessive Valve Noise
Causes: Excessive valve noise is usually caused by excessive fluid flow rate or improper valve design. Noise generation may be related to the following factors:
Excessive flow velocity:When fluid flows through a valve, especially in ball or butterfly valves, excessively high flow velocities can cause turbulence within the valve, generating noise.
Inadequate valve design:Some valve designs are unsuitable for high-flow or high-pressure environments, leading to significant impacts between the valve body and the fluid, resulting in noise.
Incomplete valve closure:When a valve is not completely closed, fluid can pass through the valve gaps, creating intense turbulence and noise.
Solutions:
Control flow velocity:Reduce the pressure difference across the valve to decrease the flow velocity and avoid excessive turbulence.
Select appropriate valve type:Choose the appropriate valve type based on the operating conditions. For example, ball or butterfly valves with low flow resistance can be used for systems with high flow rates.
Ensure complete valve closure:Regularly check the valve's sealing performance to ensure a proper seal when closed, preventing leakage and noise.

5. Excessive Valve Operating Torque
Causes: Excessive valve operating torque is usually caused by the following:
Overly Tight Valve Seal: Severe wear of the sealing surface or improper sealing during valve installation requires greater torque during operation.
Rust or Corrosion of the Valve: Rust on the valve's opening and closing parts, valve stem, etc., increases friction.
Insufficient Lubrication: Lack of lubricating oil or deteriorated lubricating oil increases friction between valve components.
Solutions:
Adjust the Sealing Surface: Check the sealing surface for wear or deformation; repair or replace if necessary.
Remove Corrosion: Regularly clean the inside of the valve to prevent rust or corrosion buildup from affecting valve movement.
Regular Lubrication: Regularly lubricate the moving parts of the valve with a suitable lubricant to reduce friction.

II. Summary
As a critical piece of equipment in pipeline systems, valves inevitably experience various malfunctions during long-term use. Timely troubleshooting and proper maintenance can effectively extend the valve's service life and ensure the normal operation of the system. When faced with common malfunctions, we need to take corresponding measures based on the type and cause of the malfunction, such as replacing sealing materials, clearing blockages, and inspecting the drive mechanism. In addition, regularly inspecting and maintaining valves to ensure lubrication, sealing, and operability are effective means of preventing malfunctions.