psv fire
psv fire
(OP)
hi,
i have read that there are country in which local authority or the law obliges the designer to consider fire like contingency even if there are procedures written that make the event very low probable or impossible. Who knows? and Italy is among these?
tx
i have read that there are country in which local authority or the law obliges the designer to consider fire like contingency even if there are procedures written that make the event very low probable or impossible. Who knows? and Italy is among these?
tx





RE: psv fire
Regarding fire exposure, typical practices in the US are different from those in Europe. The default practice in the US is to consider including fire exposure in the relief design whenever the vessel is at risk of exposure to a pool fire. That's not true in Europe. The default practice in Europe is to not consider fire exposure in the relief design.
I don't know the explanation why - it's just a difference in the risk management practices which evolved over the past century.
RE: psv fire
I think this practice is good, but now i must comment an engineering study of another engineering society and i don't know how to impose it.
I think it's need a risk evaluation for exclude fire design!
what do you think?
RE: psv fire
Procedures may make something low probability, but they don't make it impossible. Your key questions should be - Can a fire develop in a location which would cause your equipment to be subject to thermal loads beyond the design max temp. If yes then you need to design for fire regardess of the likelehood, especially if a potential consequence is leak, rupture or over pressure. This should normally come out in a HAZOP or HAZID, but much better to design it in at the start rather than having to do mods to the design after a HAZOP.
I've never designed anything like that in Italy, but they have a decent safety culture there and it would certainly be something that needs to be considered and only not allowed for if it is physically impossible or doesn't have an impact on the equipment.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: psv fire
I always consider fire case, but if I can't come up with a pool of flammable liquid then it is not credible. If I can't come up with a scenario (in a vessel which contains liquid with a flashpoint >200 F) that results in the vessel becoming liquid full and blocked in coincident with a pool of flammable liquid then it is not credible. I rarely have a credible fire case in low pressure gas/water field systems--with the minimal liquid inventory boiling all the water doesn't lift the PSV (in most analysis) and once the liquid is gone the metal will flow before the ideal gas law can lift the PSV.
David Simpson, PE
MuleShoe Engineering
"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
The plural of anecdote is not "data"
RE: psv fire
Good luck,
Latexman
Need help writing a question or understanding a reply? forum1529: Translation Assistance for Engineers
RE: psv fire
All codes and standard intentionally leave it to the user to determine the sizing basis for reief devices. That's true in ASME jurisdictions and in PED jurisdictions such as Italy. As I mentioned above, engineers in Europe don't generally design for fire exposure the same way we do in the US. That doesn't mean they're wrong. It just means that they apply risk management practices differently.
It appears that the OP (gelsi) is being asked to comment on some relief designs which were done by others. Gelsi, my suggestion is that you point out the areas in which fire exposure is a risk, and recommend that the owner assess this risk against their corporate risk tolerance. Maybe this will result in some fire sized PRVs and maybe it won't.
RE: psv fire
Good luck,
Latexman
Need help writing a question or understanding a reply? forum1529: Translation Assistance for Engineers