Sizing a psv on a pump discharge line

[9751jld]

With all things I have done as an engineer, I have never sized a psv.

This psv is on the discharge of a 2x1 centrifugal pump that circulates hot water in a closed system to provide heat to a couple of jacketed vessels then back to and through a small hydronic boiler. Temp of product is 45 degrees C +/- 5 degrees C. Psv on the boiler is set at 45 psi.

How do I size and select the psv on the discharge of the pump?

I suscribe to the statement that the only dumb question is the one you don't ask. I'm asking.

Thanks,

9751jld

 

[pleckner]

What are you trying to protect?

 

[9751jld]

The jacketed vessels being utilized are not coded vessels...they were purchased used from who only knows where. Prior to their being placed in service (and this has not happened as of this writing)the jackets were filled with water and 10 psi air pressure was applied. The gage held for over an hour. This was the only test performed, and that was just to see if there were any leaks...none appeared. I do not know the vessel wall thickness, nor the jacket thickness...no one has determined this.

With all this said, I think the answer to your question would be protection of the integrity of the jacket and shell. There is no evidence from inspection inside the vessels that baffles were installed with the installation of the jacket(s).

Plans are to blanket the product with dry instrument air at 2 psi just to keep out moisture, and the PSV on the vessels are to be set just above this...at least that is the current plan. Sizing the vessel PSV's, to me, would be based on the charge rate of the product when filling/refilling the vessels. This product will be pumped into the vessels, and when level is reached pumps will shut down and hose disconnected to fill line.

I apologize for being so wordy, but I hope I have answred you question.

9751jld

 

[dcasto]

The whole system is your risk management. I'd gather data like wall thickness, ACTUAL density of the fluid in the vessel and look at all the hydraulics. Then decide where to go from there.