When do you use a Ball Valve followed by a Globe valve?
When do you use a Ball Valve followed by a Globe valve?
(OP)
Hello,
I'm looking at a P&ID with an inlet ESD Valve with a bypass around it that contains a ball valve followed by a globe valve.
This may be a very basic question but, can someone please tell me what the basis is for having a ball valve in series with a globe valve?
thank you.
I'm looking at a P&ID with an inlet ESD Valve with a bypass around it that contains a ball valve followed by a globe valve.
This may be a very basic question but, can someone please tell me what the basis is for having a ball valve in series with a globe valve?
thank you.





RE: When do you use a Ball Valve followed by a Globe valve?
Is the globe valve perhaps for modulating control, with the ball valve simply to isolate it for maintenance?
Can't tell for sure without looking at the P&ID...
Good on ya,
Goober Dave
RE: When do you use a Ball Valve followed by a Globe valve?
Thanks for the response.
Sorry I can't upload the P&ID, but just picture a normally fully open ESD valve on a line with a bypass around it for maintenance. The bypass line has a ball valve and globe valve in series. that's it. no other blinds or hardware.
The ESD is normally full port open and is not modulated. There is no control required at this point, it's not like a bypass around a control valve.
thanks again,
Juujee12
RE: When do you use a Ball Valve followed by a Globe valve?
There must be some system specific reason.
One guess is to manually throttle flow around the ESD when it is closed.
Of course this defeats the purpose of the ESD.
RE: When do you use a Ball Valve followed by a Globe valve?
hope this helps.
-pmover
RE: When do you use a Ball Valve followed by a Globe valve?
thanks again to everyone for your help!
RE: When do you use a Ball Valve followed by a Globe valve?
The reason why you cant move the valve is in he way the seal work that prevents the valve from leaking.
The globe valve is of course for a controlled release - sometime a RO is used instead.
Best regards
Morten
RE: When do you use a Ball Valve followed by a Globe valve?
RE: When do you use a Ball Valve followed by a Globe valve?
Assuming the arrangement to be on a high pressure gas facility. The pressurisation is manally controlled to prevent (minimise) the seat erosion on the ESD valve. Also J-T cooling can result in temperatures below the MDMT. On some arrangements, eg compressors with auto start, the pipework downstream of the globe valve is stainless steel. The globe valve will be on the low pressure side (or the maintainable side).
The larger ESD valve can be a rotating seat so that the same bit of seat is not subjected to the wear in the same point.
RE: When do you use a Ball Valve followed by a Globe valve?
Only put off until tomorrow what you are willing to die having left undone. - Pablo Picasso