What is the significance of Maximum DeltaP shut off for valves? Is it applicable for a Self regulated Valve? or only for ESD Shut off valves and Control valves? In some cases, the Max shut off Differential pressure is given as Design pressure. is it correct? Please guide

 

Maximum shut off DP is vital to size the actuator of the valve. If the DP is less, the actuator size will be small. As the DP increases, the actuator size also increases. If your valve actuator is not sized properly, when there is maximum DP across the valve (e.g., valve is fully closed), you may not be able to open the valve. This is equally important for regulators, control valves or shutdown valves.

Nomally at the initial design stage people are not sure what could be the maximum DP across the valve. One safe escape in that situation to consider the pipe line design pressure as the maximum DP across the valve. Because at any time the pressure in the pipe line will not be more than the design pressure of the pipe line.

Hope this helps.

 

Whether Maximum DP of ESD Valve be greater than Line Design Pressure? I have seen it in ESD Valves Data Sheets.

 

It's absolutely true. Best thing to design the Shutdown valve actuator for shut-off pressure as system/pipe design pressure. In this case valve opening is ensured for a differential pressure across the valve equal to design pressure.

Now, I have query to any person who is working as valve vendor.

Is it possible to design the actuator for lower pressure than design pressure. It will be designed as below:

1. Valve body will be designed for pipe Design Pressure (say 40 barg)

2. However, actuator will be designed for 5 barg. This means valve will not operate or open/close if the differential pressure is more than 5 barg.

Thanks,
Ray

 

Hi all

> However, actuator will be designed for 5 barg. This means valve will not
> operate or open/close if the differential pressure is more than 5 barg.

From my current design, a main ESDV (12") can not be operate if the differential pressure is more than 10 bar. We have a PDT across the main ESDV. in parallel of this previous ESDV, we have a small on/off ball valve actuated, ESDV also, 2". The purpose of this 2nd ESDV is to be open first in order to reduce the differential pressure and to reduce the size of the actuator of the main ESDV.

regards