Help on calculating required relieving capacity
Help on calculating required relieving capacity
(OP)
I have found various sources (including manufacturer's websites) that tell me how to determine relieving capacity of a burst disk given a relieving pressure and disk size. I have read articles on Coefficient of Discharge and Resistance to flow methods.
However, how do I determine the REQUIRED relieving capacity?
Is this typically something that a customer purchasing pressure equipment would determine based on his application and require the vessel manufacturer to meet?
Any helpful pointers from the forum would be much appreciated!
However, how do I determine the REQUIRED relieving capacity?
Is this typically something that a customer purchasing pressure equipment would determine based on his application and require the vessel manufacturer to meet?
Any helpful pointers from the forum would be much appreciated!





RE: Help on calculating required relieving capacity
API 520 has a list of categories of credible scenarios. Some are very specialized (e.g., one of them is runaway chemical reaction which is rarely credible for a 2-phase gas/liquid separator on a wellsite), some must be considered nearly always (e.g., fire case and blocked outlet case).
The process for finding required flow rate is to run through the API 520 (or 521) list and determine which scenarios are credible. For the ones that are credible you need to assess the flow rate during that scenario. Size your device for the largest flow credible flow rate.
David
RE: Help on calculating required relieving capacity
Would you agree though that the customer is in a better position to determine the required relieving capacity than the manufacturer?
Is this responsibility placed on the customer anywhere within the ASME code? Since the API is not really a "code" I would expect it would not be specified therein.
Thanks!
RE: Help on calculating required relieving capacity
Also, for our litigenous business environment, DO NOT take on the PRV / overpressure liability. Put "Pressure Relief Device(s) to be Supplied by Customer" in ALL your contracts.
RE: Help on calculating required relieving capacity
RE: Help on calculating required relieving capacity
RE: Help on calculating required relieving capacity
I don't agree with the concept of just marking "supplied by others". I think it should be a collaboration. For example, I wrote a vessel RFQ just this afternoon where I evaluated the credible scenarios, picked the one with the highest required rate, and provided that flow rate to the vessel fabricator to size an over pressure protection plan. I don't expect the fabricator to know what my process can give the vessel, but I don't think it is reasonable for the end-user to develop PSV sizing expertise.
David