Use of Gate Valve for Throttling 3

[ASA2025]

Hi All,

I would appreciate your insights regarding the temporary use of a gate valve for throttling service. Specifically, I would like to understand:

1. What potential issues or risks could arise from this mode of operation?
2. What would be an acceptable duration for operating the valve in this manner?

Technical Details:

• Valve Size: 24"
• Valve Trim: SS316
• Operating Fluid: Cryogenic

Thank you in advance for your support and valuable feedback.

 

[LittleInch]

You don't say what pressure drop or flow you're expecting or why this needs to be done?

Issues - low control of flow. Small movements of the gate results in much bigger changes in DP / flow
Depending on the design of the valve ( cross section would help as "Gate valve" can mean many different configurations) you can easily destroy the seat and or gate meaning it wont seal. Not sealing after use is highly likely.
Erosion and or cavitation could lead to destruction of the gate meaning no valve left.
If this is a high DP throttling ( anything more than 1-2 bar) your control function is very poor and damage to the valve very likely.
Valve may fail completely.

"Acceptable" duration for me would be limited to minutes, not hours, but even this could result in damage to the gate and seals.

Overall, this is a poor decision, IMHO, that has significant risks that need to be understood and accepted or mitigated. E.g. you absolutely need a second valve in series which can be relied upon to cease flow when you need to and not rely on this gate valve.

Is that what you wanted to know?

 

[ASA2025]

Thanks a million, LittleInch, for your response.

We are evaluating the use of the gate valve to generate backpressure for supporting system equipment rather than for precise flow control.

At this stage, data on the valve’s performance under throttling conditions is limited to what I’ve already shared. You’ve correctly highlighted the principal risk—damage to the gate and its seals, which likely applies across most configurations.

Could you clarify what other failure modes might result from this proposal? Specifically, beyond gate and seal damage, is there a risk of loss of primary containment that could result in a release?

 

[TugboatEng]

What do you have to lose if the valve fails?

-Does failure pose a safety hazard?
-Does it pose an environmental hazard?
-Is needing to repair or replace the valve an acceptable cost?
-Is the loss of control of the process going to result in loss of valuable product?
-Are there other components in the system that may be damaged by excessive vibration or debris from the valve?

 

[goutam_freelance]

As the wedge will lose contact with the seats under low flow conditions, vibration of the wedge may occur, which may damage the wedge and seats.

 

[TugboatEng]

And the guides and the stem to disk connection.

 

[LittleInch]

Thanks a million, LittleInch, for your response.

We are evaluating the use of the gate valve to generate backpressure for supporting system equipment rather than for precise flow control.

At this stage, data on the valve’s performance under throttling conditions is limited to what I’ve already shared. You’ve correctly highlighted the principal risk—damage to the gate and its seals, which likely applies across most configurations.

Could you clarify what other failure modes might result from this proposal? Specifically, beyond gate and seal damage, is there a risk of loss of primary containment that could result in a release?

I doubt you would get actual valve body failure but not impossible if you get a lot of vibration.

Difficult to speculate without more details.

Isolation valves ( ball, gate etc) get used all the time as throttle valves when they shouldn't and survive. For me the risks of body failure are very low, with risk of damage to the valve and seals very high. That's about all you can say really at this level of detail.