Drain valves on LPG pipework

[jonesey]

Does anybody have any experience of what type of drain valves are best to use on LPG lines, where the risk of water contamination exists ? We have used plug valves in the past, but they tend to jam up and sieze solid. A number of years ago we switched to ball valves, but the seats tend to wear and require replacing. The main problem is that the valve can freeze up when draining. This is particularly a problem after pressure testing when mositure can still be present in the line.

 

[TD2K]

I would think any valve is subject to this problem. Drain valves on LGP services are commonly installed as an upstream ball or gate valve with a downstream globe or other type of throttling valve. The intent is that the ball or gate valve is first opened FULLY and then the globe is used to throttle the LPG (and take the pressure drop/flashing). If the globe freezes and can't be closed, the upstream valves CAN be closed as they are taking no dP and are still warm.

Might want to consider using a temporary threaded connection with a downstream globe or other valve so you still have the upstream root valve available to isolate the piping if needed.