Overpressure protection of HC liquid cartiridge filters and HC-wtaer liquid coalescers
Overpressure protection of HC liquid cartiridge filters and HC-wtaer liquid coalescers
(OP)
Would appreciate very much any feedback on overpressure protection design for hydrocarbon liquid cartridge filters and hydrocarbon-water liquid coalescers. I am working on a system which has a cartridge filter located upstream of the coalescer to filter out any solids to prevent plugging of the coalescing element. To prevent over pressuring during external fire how many PSVs (pressure safety valves) should be installed on each vessel - one (1) on each side of the filter cartridge and coalescing element or just one (1) upstream of the elements? It seems the safer design would be to install two (2) PSVs on each vessel. If only one (1) PSV located upstream of the filter or coalescing element is used the downstream section without the relief valve may be over pressured because of possibly high pressure drop thru the element. Also, there is a possibility of filter cartridge being plugged. Would like to know about some actual design and what is the industry practice. Thanks.





RE: Overpressure protection of HC liquid cartiridge filters and HC-wtaer liquid coalescers
Please upload a simple sketch of the system you described included the valves. It can help to submit better response to your query...
RE: Overpressure protection of HC liquid cartiridge filters and HC-wtaer liquid coalescers
A psv on each is best. A common psv is a cheaper design which puts administrative burden on operations.
Best wishes,
Sshep
RE: Overpressure protection of HC liquid cartiridge filters and HC-wtaer liquid coalescers
sshep: Did you mean a PSV on each vessel or each side of the vessel which would mean 2 PSVs on each vessel? Also, I did not understand the "administrative burden on operations" if one (1) PSV is used. Will one(1) PSV require more frequent inspections? Could you please clarify that comment. Thanks.
RE: Overpressure protection of HC liquid cartiridge filters and HC-wtaer liquid coalescers
RE: Overpressure protection of HC liquid cartiridge filters and HC-wtaer liquid coalescers
One on each vessel, upstream the internal elements.
There is no need for the second PSV on each vessel.
However, the 1.5 x 2 relief valve does seem small for the fire case
RE: Overpressure protection of HC liquid cartiridge filters and HC-wtaer liquid coalescers
What is your problem with current configuration? Because there are manual isolation valves between filter and coalescer, both equipment can't be protected with one PSV. Indeed, provision of the spare for PSV isn't mandatory per API and ASME Sec. VIII, then appears current configuration to be acceptable. With the limited info you are provided seems credible scenarios are blocked outlet and fire case, and if only fire case is credible scenario it's not unusual to install one PSV on the equipment is to be protected and the spare PSV to be kept in warehouse in saving standpoint...
RE: Overpressure protection of HC liquid cartiridge filters and HC-wtaer liquid coalescers
RE: Overpressure protection of HC liquid cartiridge filters and HC-wtaer liquid coalescers
RE: Overpressure protection of HC liquid cartiridge filters and HC-wtaer liquid coalescers
No need to connect the PSV to downstream side of the cartridge at all, because the source of over pressure is at upstream side of the cartridge...