Pressure Relief Valve Nozzle Orifice Designations 1

[AljosaM]

Hi all,

I have a quick question on how nozzle orifice areas are classified according sizes. (Sorry if this is in the wrong thread; I thought it fits best here since to my understanding, the BPV Code, Sec. VIII, Div. 1 is used as a primary design basis on pressure relief valves. Please correct me if I'm wrong.)

See the attachment. It's a snapshot taken from a typical PRV catalog showing the nozzle designations. I have seen the table with the same values in literature from different vendors, but I wasn't able to find it in the BPV code. Am I just looking in the wrong place? Is there some other ASME code which is used for pressure relief valves? If so, please point me in the right direction.

Thanks for the help.

 

[EmmanuelTop]

Relief valve orifice areas are selected according to API RP 526, "Flanged Steel Pressure-relief Valves". These effective areas are valid only when used with the sizing equations contained in API RP 520 "Recommended Practice for the Design and Installation of Pressure Relieving Systems in Refineries", Part I - Sizing and Selection.

Dejan IVANOVIC
Process Engineer, MSChE

 

[AljosaM]

Thank you for reply, Mr. Ivanovic.

Just for clarification, what you are saying is that if the valve was sized according to ASME Sec. VIII Div.1, the orifice designation is not applicable? Does ASME have its own designation tables?

I have received many valve datasheets for a project, and my vendor has written an orifice designation of 'F', but has specified ASME Sec. VIII Div.1 as a design basis. I feel this is incorrect.

Thanks.

 

[EmmanuelTop]

There is no such procedure for PRV sizing based on ASME Sec. VIII Div 1. I think what the vendor stated is that the relief valves are (or will be) ASME-certified. See UG-131 of ASME Sec VIII Div 1.

The actual valve delivered by the vendor does not need to have orifice area according to API 526, but its capacity (the required relief flow) must be ASME certified.

Dejan IVANOVIC
Process Engineer, MSChE

 

[AljosaM]

I understand now. You are correct, the ASME certification is a requirement, but not the API sizing.

Thanks again.