Dear all,

I am looking for guide for sizing PSV i.e. step by step approach for sizing PSV. Can anybody please share if they have any document for this or any website related to this. I dont want link for any free software because first I want to learn basic of PSV sizing. I have read API STD 521. But still its not much clear to me.

Thanking you all in anticipation.

Cheers,

Gunjan

Sizing a PSV is not the difficult part, determining the controlling relieving scenario and the associated flow and conditons is. To determine the controlling relieving scenario involves a deep understanding of the process segment and a mini-HAZOP if you will. API Std 521 will tell you all about the potential relieving scenarios and API RP520 will give you the equations to use once you determine the controlling scenario and conditions.

There is an overwhelming number of articles on this subject. However I'm going to make it simple (well, a little more simple). The following references are need (in my opinion) at the very least if you are going to be seriously involved in this area of engineering associated with chemical/petrochemical/refinning/agricultural/biopharmaceutical, etc. processes:

1. The latest edition of CODE (either ASME or the PED or whatever your place of origin considers CODE)
2. The latest edition of API RP520
3. The latest edition of API Std 521
4. A book published by the Center for Chemical Process Safety (CCPS) of the American Institute of Chemical Engineers (AIChE), "Guidelines for Pressure Relief and Effluent Handling Systems", 1998

Additionally, if you are going to get into two-phase relief you need the following:

1. Reference "4" above
2. Leung, J.C., "Easilly Size Relief Devices and Piping for Two-Phase Flow", Chemical Engineering Progress, December 1996
3. Fisher, H.G. et al, "Emergency Relief System Design Using DIERS Technology, AIChE, NY, 1992

And let us not forget posting specific questions you may have here on this Forum.

Yes, this is almost overwhelming in of itself but these are necessary references because the subject must not be taken lightly. You cannot expect to be proficient in PSV analysis and calculations over night. This is why I strongly suggest a novice should never be allowed to perform these calculations unless there is an experienced (in this area) engineer looking over their shoulder.

To make it really, really easy for you, go to a PSV vendor's website and look at the technical section in their cataloges. This will give you a basic overview. Two in particular are Farris Engineeirng (http://www.farrisengineering.com/Products/products.htm) and Anderson-Greenwood (http://www.andersongreenwood.com/).

Then if you get into low pressure vessels, you need to deal with various NFPA standards, API 650, API 620 and API 2000. You see, this isn't a subject for the weak at heart!!

Also, have a look at GPSA Engineering Databook Vol 1 for a good description of relief sizing.