I'm a new engineer less than a year out of college. I'm working in the upstream Oil and Gas sector designing central processing facilities and tank batteries.
My question is regarding control valve sizing and line sizing.
Is it typical for control valves to be smaller in size than the line they are controlling?
Typically, I size lines for pressure drop below 1 PSI/100ft and Velocity below API 14E recommended. The control valve has almost always been a pipe size smaller than the line itself.
It makes sense to me theoretically because the valve needs to have good ability to throttle flow. I just want to check and make sure I'm not missing something here.
I know differential pressure across the valve plays a big part in the control valve sizing to determine Cv of the valve for the required flowrate Q.
Choked flow occurs in Brine level control valves coming from the separators and going to tanks, but Differential pressure is not large enough on any other control valves I'm referencing to have choked flow conditions.
And I know there are exceptions and different situations but generally is this the case, Control Valves being smaller than the Line size?
Thanks,
New Engineer