Pressure relief requirements for non-code vessels
Pressure relief requirements for non-code vessels
(OP)
My company is designing a water treatment system that will use several pressure vessels (ambient temp water, approx 300 gallons capy) that are not ASME code stamped and a few questions come to my mind:
1) If it's not an ASME code vessel, what regulations govern it?
2) Is over pressure protection required, and by whom?
If it were an ASME code vessel my extremely limited knowledge based on excerpts I've found of the code suggest to me that they would need OP protection from the feed pump as well as OP protection from thermal events and blocked-in conditions. Is that accurate? But what if it's not an ASME vessel. What then?
Thanks much,
John
1) If it's not an ASME code vessel, what regulations govern it?
2) Is over pressure protection required, and by whom?
If it were an ASME code vessel my extremely limited knowledge based on excerpts I've found of the code suggest to me that they would need OP protection from the feed pump as well as OP protection from thermal events and blocked-in conditions. Is that accurate? But what if it's not an ASME vessel. What then?
Thanks much,
John





RE: Pressure relief requirements for non-code vessels
RE: Pressure relief requirements for non-code vessels
Regards,
Mike
RE: Pressure relief requirements for non-code vessels
Cheers,
gr2vessels
RE: Pressure relief requirements for non-code vessels
Correctly qualified as pressure vessels? To my way of thinking they must be – they aren’t atm tanks, but perhaps there is some framework in which they don’t qualify as PVs (not a smart alec comment, maybe there is some language or exception for water treatment or something). I don’t see how they could fail to be classified as PVs but I have been wrong before. These are one of the types being used: http://www.yardneyfilters.com/sand_media_filters_i...
The state in which these vessels will be operated is MD and based on what I read last night at this URL, all new pressure vessels must be ASME stamped: http://www.dllr.state.md.us/labor/safety/boil.shtm...
I did not investigate beyond that page as it seemed pretty clear.
My belief is that OP protection is required for two scenarios: 1) OP due to the feed pump which is capable of generating pressure that exceeds the MWP of these vessels by 30% and 2) OP protection for a completely filled vessel (water), blocked in during a system shutdown during freezing weather. Relief for fire, internal reactions and such aren’t possible with this process.
Some in my company believe that the MD building code, which I haven’t read (don't yet know if they have), has jurisdiction. I’ll look at it on Monday, but given the language in the MD link above, the bldg code would have to come up with some exemption based on size, intended usage, or some such. Further my people state, and I don’t know on what basis yet, that “Boiler codes, or any codes related to the handling of steam and condensate systems are not applicable to our treatment system”. The problem I see with that is this phrase from the MD code: “The Law also requires that any Boiler or Pressure Vessel that will be installed in Maryland be built to American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code and be registered with the National Board of Boilers and Pressure Vessel Inspectors.”
We didn’t really write a specification for the vessels, just said “those ones”! Pretty hot shot engineering, eh?
You guys are going to be laughing at me…but at least I'm swinging the bat in the right ballpark.
Thanks a lot to you all!
RE: Pressure relief requirements for non-code vessels
Regards,
Mike
RE: Pressure relief requirements for non-code vessels
RE: Pressure relief requirements for non-code vessels
So OP protection devices are not required for ASME code compliance on water pressure vessels operating up to 300 psig and 210F. I wonder if there are any vessel size limits that apply to that. I know of a couple of 20,000 gallon ASME vessels that operate at 120 psi and ambient temps, and have OP protection; it's counter intuitive to me that the code wouldn't require OP protection on such a large vessel. Then again, maybe it would just fracture, relieve and not really cause damage, though 120 psig jets could put a hurt on a person, never mind a 299 psig jet!
I'll do some more reading.
Thanks again.
RE: Pressure relief requirements for non-code vessels
Again, your jurisiction may dictate differently.
Good luck,
Mike
RE: Pressure relief requirements for non-code vessels
I found that the ASME code has been adopted by the state and I see the citation you noted. I wonder: Is there some other division of the ASME code that addresses the requirements for water vessels at 300psig & 210F or less? It just doesn't seem reasonable to me that pressure relief devices (and headspace air control) aren't required on vessels, of apparently unlimited size, containing, say, 290psig/200F water. Am I missing something?
I'm trying to find a local copy of the code but no luck so far.
John
RE: Pressure relief requirements for non-code vessels
It sure looks like there are no requrements for pressure relief. Now if gas can accumulate in the headspace (they are downflow vessels) from entrained air (pretty unlikely) or biological activity (not out of the realm of reasonable possibility) then things would seem to change. I need to see where the code quantifies the amount of headspace gas that is acceptable, and the amount that makes this a pressure vessel or something requireing gas release.
RE: Pressure relief requirements for non-code vessels
For example, if I remember right, vessels less than 6" diameter are exempted from the ASME Section VIII. That doesn't mean if a 7" vessel blows up, it's dangerous, but if a 5" vessel blows up, it's perfectly safe. It just means one is addressed by the code, the other isn't.
There are a lot of items designed that do not fall under a specific code of construction, and non-code vessels are one of those. They may be covered to some extent by building codes or by tank standards or pipe standards, etc. Where not covered by a standard of some kind, good engineering practice would be to make it as safe as similar items furnished under other circumstances.
RE: Pressure relief requirements for non-code vessels
RE: Pressure relief requirements for non-code vessels