Actuator MAST


I'm encountering a problem in my Project for the procurement of Pneumatic spring return ESD valves. In the Sizing calculations, for some valves the Actuator MAST is exceeding the Valve MAST, which I believe is not desirable.

I cannot change my DP on line & cannot reduce my safety factor (2). What is the solution now?

Can i proceed with Actuator MAST higher than Valve MAST?

Thanks in Advance!

Having now understood MAST (Maximum allowable stem shear torque), it would seem a bad idea to have the Actuator MAST exceeding the Valve MAST as you could end up with a damaged valve.

Can you explain what calculations you are making?

If these are spring return, are they fail safe closed or fail safe open?