Hi,
I have been looking into the capacity certification of PSVs by ASME code and how it confirms the rated capacity of PSVs as well as the rated coefficient of discharge.
Considering API 520& API 526 are preliminary starting points for calculating the required and selected effective coefficient of discharge and effective area based on the required relieving capacity,
At the early design stage and prior to PSV procurement, selection and testing certifications,
In order to perform the initial sizing of PSV inlet and outlet tail pipe sizes based on the 3% non-recoverable pressure losses and backpressure criteria respectively (except for modulating type pilot operated PSVs where required relieving capacity will be used), what would be the most recommended estimation of an initial PSV rated capacity in order to perform such calculations, would be assumed based on the the 10% ASME derating factor or this step mandates initial screening of actual PSV rated capacities available in the market for similar API 526 effective area designations.
Thanks