Cavitation in Control Valves
Cavitation is a damaging phenomenon that can occur inside a control valve when liquid flows at high velocity and pressure drops rapidly.
What Causes Cavitation?
- High-pressure drop across the valve causes the fluid pressure to fall below its vapor pressure.
- This leads to the formation of vapor bubbles inside the fluid stream — often just downstream of the valve plug or orifice.
- As pressure recovers further downstream, these vapor bubbles collapse violently, releasing energy that hits metal surfaces.
Why Cavitation Is Dangerous
- Erodes the valve trim and body
- Causes vibration and noise
- Reduces valve lifespan
- Leads to system inefficiency and failure
How to Prevent Cavitation
- Use multi-stage pressure-reducing trim
- Select low recovery coefficient valve types (e.g., globe valves)
- Install anti-cavitation cages or special trim designs
- Limit pressure drop across the valve when possible
- Consider flash-resistant materials if cavitation is unavoidable
Real-World Tip:
Cavitation is most common in high-pressure drop liquid services — like pump discharge lines, steam condensate return, or hydrocarbon transfer.
Proper valve selection and trim design are critical in avoiding costly damage.