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Wednesday, February 27, 2008

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In earlier post "Should we consider JET FIRE for Pressure Relief Valve (PRV) load determination ?", there were few main points discussed. Among all, there are

i) Pressure Relief Valve (PRV) may not protecting equipment and/or system from FIRE attack

ii) External FIRE (regardless of POOL or JET fire) for gas filled vessel will probably fail the vessel before the internal pressure reach its PRV set pressure.
Similarly for a high boiling point liquid stored in a vessel or tank exposing to external FIRE, the vessel may fail prior to the internal pressure reach its PRV set pressure. For a gas filled and high boiling point liquid vessel, there shall be other protective measures in place in order to avoid or minimize the consequent of catastrophic failure due to FIRE.

What are other protective measures against FIRE you may consider other than Pressure Relief Valve (PRV) ?

(i) Depressuring (vapor & Liquid)
Depressuring is one of the effective protective measures against FIRE attack. Depressuring (a) relocate hazardous fluid to SAFE area and (b) decrease the internal pressure of vessel or tank under fire attacked. Somehow, please don't misunderstood depressuring.

(ii) Provide Rupture / bursting disc instead of Pressure Relief Valve (for system that will lift PRV)
Rupture disc (RD) will burst in the event of overpressure. With the bursting of RD, it (a) relocate hazardous fluid to SAFE area and (b) decrease the internal pressure of vessel or tank under fire attacked.

(iii) External cooling (deluge & spraying)
In Steam in FIRE, it's been discussed that water is an inert agent it has the potential (vaporization and specific heat) of removing heat released by FIRE. Provide fixed deluge and spraying system around equipment is one of the effective protective measures.

(iv) Fire Extinguishing agent (with external cooling)
In the fixed deluge and spraying water system, may consider to mix water with fire extinguishing agent e.g. foam. As water mixed with foam is sprayed, foam in water with high surface tension will tends to capture air in the bubble and form barrier between fresh air, fire and material under fire. Other than foam deluge and spraying system which normal directly spray on the equipment, may also consider to provide fixed / portable foam pouring system. It works exactly the same as foam deluge system, however, it target on the material under fire which is normal in stay in bunded area. For fire potential occur in hydrocarbon storage tank, fixed / portable foam pouring system can be used to extinguish fire in the tank.

(v) External Insulation
This is another effective measure. Providing external fire resistance insulation will minimize heat input into vessel or tank and to avoid/ minimize internal overpressure and failure of vessel or tank. It associate with reliability issue of insulation and internal corrosion issue.

(vi) Sand Cover Storage
This method works similar to external insulation where it isolate the vessel and its content from any external fire. However, it associate with corrosion issue.

(vii) Diversion wall for isolation and proper drainage
This is one of the effective measure to minimize / avoid escalation of fire from one area to another area. Basically the concept is to provide bund wall around equipments. In the event overfilling or vessel rupture and caught fire, it content is capture in the bunded area and fire will not escalated to other vessel. Proper drainage system is one is measure should be in place in order to evacuate any hydrocarbon liquid to SAFE area.

(viii) Reliable & Compatible Fire detection system
Conduct detail safety and fire analysis and provide reliable and compatible fire detection system around the high fire potential areas. This includes redundancy of fire detectors (sparing, diferrent detection technology, etc) and compatibility (correct fire detector for type of fire).
So do you have any more to add ? Why not share with us here ?


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posted by Webworm, 12:30 PM

1 Comments:

Blogger Martha said...

These are all good protective measures against fire particularly Fire Detection Systems. Obviously this is all dependent on the layout, structure and site use as well as a number of other factors.

December 1, 2010 at 3:00 PM  

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