Vacuum relielf Valves

[Barhp]

Dear,

I am working in a cryogenic ethylene tank turnaround. The vacuum relief valves are set to open at -20 mmH20 and during manteinance they were calibrated at -28 mmH20, my question is: is there any problem with the set pressure? is the integrity of the tank at risk because of the new set pressure?

What would you recommend?

Any help?

Thanks

 

[ash9144]

What is design pressure of tank? If tank design is -20 then thats what the vacuum relief should be set to.

Do you mean mmHg? rather than mmH2O

 

[Barhp]

Design Pressures:
Inner tank: 1000 mmH20
Outer Tank: 25 psf (inclds vac)

 

[Chance17]

Ash9144: I don't see your answer as being accurate. If the tank design is -20, the set pressure should be less vacuum. The device is evaluated at contingency flow to ensure -20 tank design is not exceeded.