Common Causes of Control Valve Leakage and Instability

Control valve leakage and instability are common problems in industrial pipelines. They may appear as poor shutoff, unstable flow, pressure fluctuation, valve hunting, noise, vibration or abnormal actuator movement. The real cause may be the valve body, trim, actuator, positioner, air supply, process condition or sizing error.

Common Leakage Causes

Common Instability Causes

• Valve is oversized and operates near the closed position.
• Pressure drop is too high, causing cavitation or flashing.
• Positioner tuning is incorrect or air supply pressure is unstable.
• Actuator force is not enough for the process differential pressure.
• Pipeline vibration or pulsating flow affects valve movement.

How to Troubleshoot Valve Instability

Start by checking the control signal, position feedback and actual valve movement. Then inspect instrument air pressure, filter regulator, tubing leakage and positioner calibration. If the actuator and positioner work normally, review the process condition and valve sizing. Oversized valves are a frequent cause of poor control because small stem movement creates a large flow change.

When to Repair or Replace

Repair may be enough when the issue is packing wear, positioner calibration or minor trim damage. Replacement should be considered when the valve body is corroded, trim is severely damaged, spare parts are unavailable, process conditions have changed or the original valve was incorrectly sized.

Santan Fluid Support

Santan Fluid helps customers troubleshoot control valve leakage, instability and replacement requirements. We can support valve body, trim, actuator, positioner and accessory selection for steam, water, chemical, oil and gas pipeline applications.