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Hydrate prevention on valves in WAG service

Hydrate prevention on valves in WAG service

Hydrate prevention on valves in WAG service

Is there any specific operational procedure that is suitable to avoid hydrate formation in valve cavities when changing from water injection to gas injection in subsea production equipment?
I would appreciate any guidance on this matter.

RE: Hydrate prevention on valves in WAG service

Leave them either in fully opened or closed positions.

"People will work for you with blood and sweat and tears if they work for what they believe in......" - Simon Sinek

RE: Hydrate prevention on valves in WAG service

For the ball valves commonly used in pipeline and manifold equipment, your proposal is valid. These valves are usually trunnion type, the seats seal against the ball, sealing the valve cavity in both closed and opened condition from upstream and downstream. Since the valve were not cycled (opened or closed), its cavity would not receive the bore fluids and hydrate should be avoided.
For ball valves “not drive it” is a good operational precaution. But I am not sure if it is enough. More than this, what should be done if the valve must be opened or closed? Which would be a suitable procedure?
In Christmas trees, however, the valves are slab gate valves. Pressure pass through the upstream seat into the valve cavity and pushes the floating gate on the downstream seat. In this situation, the cavity of a closed valve will be filled with water during the water injection phase. When the operation is changed to gas injection, gas will enter into the cavity and hydrate shall block the valve.
My main concern is regarding the gate valves. This valve seems to be prone to hydrate blocking. Is there any procedure to avoid it?
Many thanks,

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