Hi Rubje,
By gas expansions I am talking explicitly about a vessel or container filled with gas which is expanded due to thermal energy input from a fire.
In many cases (but not all) the design temperatures of the vessel and associated equipment is often exceeded because of the large amount of...
Relief temperatures exceeding design temps are quite common in gas expansion scenarios and care must be taken to ensure the PSV will actually relieve before this occurs.
Latexman gives good advice in sizing for the highest credible relief load, however, you need to establish whether this is just...
@Rubje You answered my question, the PSV is the in the vapor space. I was considering if the setting media might have something to do with a low relief.
To Latexman's point, even 90% operating to set pressure is probably too close for a SOPRV (normal operating pressure)
Would help to have a more information on the actual application and service too. I know you said it's on a boiler but in cases where a PSV is normally seeing liquid and then is exposed to a gas this can cause early valve lifting in the range you're talking about.
Something worth considering which I think has been overlooked here is the seat tightness of the pressure relief valve (SOPRV).
If we consider a standard like API-527 then maintaining a normal operating pressure of 90% (or even 95% of set pressure) is asking for issues
Hi All,
Just looking to get people's experience with PSV sizing and selection from both the operator and vendor point of view.
In my experience, people tend to either send so much process or application information that they could have completed the exercise themselves or so little that it any...
There have been some substantial changes to the relevant specifications in the last 20 years, I do notice a lot of people seem to be using services like Scribd for access to old documents which exacerbates this problem.
The temperature compensation factor should be outlined in the manufacturers...
Hari Mech,
I have found University libraries to be pretty helpful when looking for this kind of stuff during postgrad.
I've actually used that exact Statoil PPT The Obturator posted as a reference before.
Try seaching the process + PFD.
Here is something I found with just a base level search...
Have to agree with the comments above, for applications outside of the bread and butter blocked flow and fire cases outlined in API 520, these should be reviewed by a specialist consultant like the one mentioned above.
I believe Smith and Burgess and The Equity Engineering Group may offer these...
gguliye,
Yes, POPRVs can also have gags.
You are correct, there is often a spring in the dome of the main valve, however, these are typically very very low rate as they would otherwise impact the performance of the valve.
Are you trying to maintain the main valve at the closed position even when the upstream pressure is low such as before a compressor startup or similar?
avalveman, this is my point.
ASME Section VIII requires us to demonstrate that the blowdown figure can be achieved, however, I feel in some cases that demonstrations requiring special ring configurations under lab conditions are not representative of in-situ(real world) performance.
I have...
The question I've often had with some of these low blowdown valve designs is one of configuration differences between bench testing and in service performance.
Some manufacturers require specific ring positions/configurations for blowdown testing which are later returned to default for field...
