In EPC projects and industrial systems, gate valves are often misunderstood. While they are excellent isolation valves, gate valves should never be used for throttling or flow regulation. Doing so can lead to premature failure, leakage, and even safety risks.

This article explains why gate valves are unsuitable for throttling, using engineering logic commonly referenced in EPC specifications.

1. Gate Valves Are Designed for Full Open or Full Close Only

Gate valves operate by lifting a gate completely out of the flow path or lowering it fully to stop flow.
They are not designed to hold intermediate positions.

When partially open:

• The gate sits directly in the flow stream
• Flow becomes highly turbulent
• The valve experiences uneven loading

EPC implication: Gate valves are isolation devices, not control valves.

2. Severe Vibration and Chatter Occur During Throttling

When a gate valve is used in a partially open position:

• High-velocity fluid strikes the gate edge
• The gate begins to vibrate or “chatter”
• This vibration transfers to the stem and bonnet

Over time, this causes:

• Stem bending
• Loosened components
• Loss of sealing integrity

Result: Unstable operation and shortened valve life.

3. Rapid Seat and Gate Erosion

Throttling forces fluid to pass at high velocity through a narrow opening:

• The gate edge and seat are exposed to continuous erosion
• Cavitation may occur in liquid service
• Solid particles accelerate wear in dirty media

Once erosion starts:

• The valve can no longer seal properly
• Internal leakage becomes permanent

EPC takeaway: Seat damage from throttling is not repairable in many designs.

4. Poor Flow Control Accuracy

Gate valves offer:

• No predictable flow characteristic
• No linear or equal-percentage control
• No fine adjustment capability

Small handwheel movements can cause:

• Large, sudden flow changes
• System instability
• Control difficulty during commissioning

Compared to globe or control valves, gate valves provide zero precision.

5. Increased Risk of Water Hammer

Partial closure of a gate valve can:

• Restrict flow suddenly
• Cause pressure surges
• Trigger water hammer events

This is especially dangerous in:

• Long pipelines
• Pump discharge lines
• High-pressure systems

System-level damage can occur well beyond the valve itself.

What Should Be Used Instead?

Globe valves and control valves.

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Final Thoughts

Gate valves play a critical role in industrial systems—but only when used correctly. Throttling with a gate valve leads to vibration, erosion, leakage, and early failure, creating unnecessary risk and cost for EPC projects.

Use gate valves for isolation. Use proper globe and control valves for regulation.

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