API 521 is a standard, not a code.
Here's a link to the API website that explains some things about API publications....
http://api-ec.api.org/publications-standards-and-statistics/~/media/A89289B7F99F4DC8944567880A9357B1.ashx
Whether you consider API 521 as mandatory or not depends on who...
Typically dual PSV arrangements on refrig units that vent to atmosphere have their own (separate) discharge pipe which would provide the greater flexibility for maintenance. Unless there is some other limitation for having a common discharge pipe, usually, you are not talking about a lot of...
Bill,
You need to be clear about what "codes" apply to your system.
You make reference to API 520 which was developed specifically as a supplement to ASME Section VIII. So does ASME Section VIII apply? If so, and there are no other exceptions to your location, then I think you are required...
The way you have worded your query is a little unclear. Are you are really breaking your relief valves? Are you looking for a reclosing spring-loaded device or a non-reclosing disk that breaks?
In any case, have you considered any of the Compressed Gas Association type devices?
Here's a...
As another consideration, typically you will not want a pop open pilot valve for liquid relief scenarios in order to avoid liquid, hydraulic hammer issues. You should consider the modulating design for liquid relief.
Here are some additional considerations...
A relief valve does not always have to be set at the design pressure but it must not be set any higher than the design pressure/MAWP for a single valve installation. So I wouldn't say you are wrong on that point but just not completely right.
As to the discussion in the thread, it is not about...
In my opinion, API did a less than adequate job covering this subject.
By ASME UG-99 the standard hydrostatic test pressure is...
"at least equal to 1.3 times the maximum allowable
working pressure (the maximum allowable working pressure may be assumed to be
the same as the design pressure when...
dcasto,
If your relief system was only a PSV nozzle, then I would agree that for critical flow conditions, the back pressure has no affect on the PSV capacity.
However, a PSV has a disk that is affected by both the amount of pressure on the upstream and downstream side of the disk. For...
Similar to dust explosions, a mist of combustible liquid can also be a concern...
http://dx.doi.org/10.1016/S0304-3894(03)00273-5
Sparging with N2 is an advantage especially if your N2 system along with your conservation vents are setup to prevent air from being pulled in.
There is some...
ASME Section VIII, Division 1, Appendix 11 explains how to perform capacity conversions for pressure safety valves. If you don't have the ASME code you can find an excerpt in the Crosby Engineering Handbook...
www.tycovalves-na.com/ld/CROMC-0296-US.pdf
Also, don't overlook contacting a local...
One other point to remember, it is not just the rating of the low pressure side of the heat exchanger that needs to be considered but the evaluation should be made for any other piping and equipment that is associated with the low pressure side of the exchanger.
On the other hand, maybe it's the service provider that needs some education... seems that is why he's here. Could be that the client has mistakenly chosen the wrong spec. Could be you don't know the full story why the client has chosen what they did. Be sure you know the full story before...
Like gr2vessels, I suspect you are referring to height. API 521 uses 25 ft, NFPA 30 uses 30 ft which is also the value that API 2000 suggests.
If your question regarding fire zone is related to a system that follows API 521, then also review the section in API 521 covering "Vapor From Fire...
Try searching for pipe covers or weather caps. Also check with your local relief valve or rupture disk supplier. I'm sure they will be more than happy to assist.
http://www.oseco.com/pages/products/holders.html
http://www.zookdisk.com/disk_holder_accessories.asp...
TheDruid,
It looks like you have taken your colleague's velocity and multiplied by the cross-sectional area of your DN20 pipe to get your flow of 200 ANm3/h.
Your units of ANm3/h are confusing to me. Tyically the "A" would indicate "actual" meaning volumetric flow based actual temperature and...
Of course you'll need to make sure your blowdown rate doesn't exceed your flare capacity or present any other concerns in case you've had to model a release from the flare without it burning.
