Pig launcher and receiver valve selection?

[antoil]

Hello everybody!!

What kind of valve should be used as a mainline trap valve
at a pig launcher and receiver(6"x8")?
Is a ,full bore, ball valve better to use,than a gate valve for pig traps?

Any help would be appreciated!

 

[zdas04]

Yes, a full-bore ball valve is considerably better than a gate valve for the barrel isolation valve on a launcher or receiver. These valves are operated frequently (hopefully) and the 80 or so turns required to operate an 8-inch gate valve will not make you popular with the operations guys.

Further, I always specify trunnion ball valves for the barrel-isolation valves (over floating ball valves) because they give you two seating surfaces between the line pressure and the trap - it can be a real pain if the barrel-isolation valve leaks through while you are trying to launch a pig.

David Simpson, PE
MuleShoe Engineering

http://www.muleshoe-eng.com

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

The Plural of "anecdote" is not "data"

 

[antoil]

Thanks a lot!!

Would you suggest this valve to be pneumatic, gear&pneumatic or just gear operated??

Thanks again for your time!

 

[zdas04]

I've used actuated and gear-operated both and below 16-inch I find the actuators to be a pain (leaks, freezes, difficulty dealing with low pressures if you pull the system pressure down, etc.).

The sequence I require for launching valves is (starting with the trap isolated and blown down, see my web page under "Samples" "Rules of Thumb for Gathering Equipment" for a description of what I think should go into a launcher design):
1. Load pig
2. Open kicker
3. Open barrel-isolation valve
4. Shut side valve
5. Re-open side valve after pig has left
6. Shut barrel-isolation valve
7. Shut kicker and blow barrel down.

With that sequence you never have any dP across the big valves so I think an actuator is a waste of money and an addition of unnecessary complexity.


David Simpson, PE
MuleShoe Engineering

http://www.muleshoe-eng.com

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

The Plural of "anecdote" is not "data"