Isolation Valve for Manifold (offshore)

[redclift]

Dear,Fellows

In Wellhead Platform design, which valve (Isolation Valve for Manifold) shall be used?
Gate valve or Ball Valve?
in my point of view for gate valve,
- it can be Broken the gate valve when open with big delta pressure.
- potential damage if wrong operation of gate valve which will sacrafice over all production if it cannot use for good process isolation.

because, i found a Wellhead platform which using gate valve as Isolation Valve for manifold (previous in my mind, only Ball valve which suitable for Isolation Valve).
and i dont know the main reason for use Ball Valve for isolation valve.

Thanks in advance for your advice/comments.

 

[MortenA]

Because gate valves are much cheaper?

 

[MortenA]

Oh yes, and because the upstream shut down valves (wing and master) are gate types?

 

[Burdy]

A lot of valves being installed in this position are trunnion ball valves.
Debris which may get trapped at the bottom of the gate can hold the gate off and stop full closure, this is not a problem with a ball valve.
The other thing is you can readily fit a Partial Stroke Device - PSD, to a ball valve. This has the ability to partially diagnose problems when the Partial stroke Test -PST is performed and meshes with today's SIS. There is less room required as you don't need the height/width. Nearly ALL ESDVs are ball valves, so I think this is rather telling of their use for isolation.

 

[BigInch]

BALLS ARE FASTER TO OPEN AND CLOSE!

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

 

[MortenA]

Im not 100% sure wrt gate valves , but large ball valves will not open with a higp dP. Im not advocating gate valves here, but you asked for possible reasons. I try to come up with some. The point about the wing and master valves being gate types is my current favorite (and the cost point).

Best regards

Morten

 

[ricklts]

Big Inch,

Actuated Gate valves require much less space/weight for the actuator (unless you are using gear reduction system or electric motors - which tend to be verbotten offshore. A hydraulic or pneumatic actuator on a gate valve will fully cycle in the about the same time as a comparable actuator on a ball valve, and require much less linear space. At least that's my experience with ESD, Boarding Valve, and Pig Launcher/Recievers offshore.

 

[BigInch]

Give me a break. You're designing offshore platforms that can't take the weight of a ball valve actuator? Come on. I've added 20 x 40 foot deck extensions to one side of existing platforms and then packed them with pipeline junctions and meters. Space, maybe I'll believe that one, but I've always been able to fit a pretty damn large gas cylinder actuator on every pipeline I've installed offshore, and it's been more than 25 times that I've accomplished that little "feet". Sorry, but none of that logic works for me.

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