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Pool fire near Portable buildings

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hammy1554

hammy1554

Chemical
Jul 6, 2020
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Hello

We have a portable wood container building with metal cladding placed approx 30 meters away from the Dike of the Hydrocarbon tank. This is potential for Pool Fire.

The building is exposed to 37.5 KW/M2 and 20kw/m2 as per the QRA report.

There will be 200 people occupying this building in the future. What kind of mitigation action we can propose.

Is there any thermal shielding that will work along with Evacuating the building in case of fire? or Only evacuation of the building would be sufficient.

If thermal shielding will help to protect the people for the period of 5,6 min of escape time, is it work to install.?
 
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Am not a technical safety engineer, but some more detail may help:
a) What hydrocarbon
b) What type of tank and is it inert gas blanketed
c) What is the max vapor pressure of this hydrocarbon at max normal ambient temp and is there a likelihood of an explosion from within this dike resulting from an overfill or tank rupture ?
d) Are there flammable gas /smoke sensors in the HVAC air intakes to this portable building ?
e) Where is the emergency generator ?
f) Are overfill high integrity ESD trip valves located safely outside the dike?

Think you get the drift - what is your emergency recovery strategy and will it hold up in the event of an explosion or pool fire ? Also have a read of the Buncefield report on safety and recovery measures in tank farms.

 
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Large containments entail serious exposure to surrounding area. Some of cases can be mitigated by implementation of countermeasures in your case dike fire or flying debris can be compensated by a fire alarm and a fireproof wall (usually made of concrete blocks). Cases spreading outside of a secondary containments (dike) cannot be revealed and mitigated in a proper way, e.g.:

distruction of surrounding area by spool of low vapor pressure hydrocarbons

fire by hydrocarbons tank disintegration

acute toxic and explosive vapor cloud exposure by spill of high vapor pressure hydrocarbons

distruction by overpressure of an extremely viscous hydrocarbons

and even a water tank can be deadly

Note that your are not the first one considers a personnel occupation premises located next to a process side is a not a bad idea

You will find much more examples searching internet or loss prevention books. Note that all of those cases were inadvertent and sudden. Two golden rules of safety engineer:
- This has never happened before and here we go again / It's brand new crap all over again
- It's all of them, I've told them [paste instructions]
 
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Guys thanks for the response. Sorry for not providing the detailed information.
The stored material is Ethyl Acetate. Dike is provided around the tank. All active safeguards and passive safeguards are available. Blast waves are not reaching to the building. Hence blast is not a concern. Toxic gas release risk is there and provided gas mask to all number of employee to evacuate.
Ambient temperature is maxed 45 in summer, Ethyle acetate boiling temp is 77.

i know no one will survive above 12 kw/m2, but is there any chance to evacuate the building before fire reach to max. like this is fire not an explosion. Pool fire or dike pool fire doesn't go to peak in seconds. Can we consider 5 min evacuation time for this?
we are not making this building to occupancy during emergency, hence in any gas leak or Tank leak there would be immediate evacuation.

Please guide if i am not in right direction.
 
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Hi,
I believe there is no way to relocate the tank or the container !
I've seen in China for such issue the erection of a brick wall between the building and the storage tank , the product was toluene .
BTW did you consult the fire brigade/EPB or the insurance broker in charge of your facility , rules should apply in your country and you won't get operating license if you don't follow them ?

Good luck
Pierre
 
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Consider following if not not done yet
1-Relocation of container to safe location.
2-The inventory in the tank to be kept at minimal.
3-Tank to be kept at idle state(means no in / out)
4-There is no integrity issue with the tank and all layers of protection are healthy.
5- Stagger the no of person to avoid accumulation in one given time
6- Use open tents are used instead of containers to have clear line of site and early evacuation

 
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A cone roof tank can have a full surface fire with maximum intensity fairly quickly, as many fires start with an internal explosion blowing the roof completely off. An open-top floating roof tank typically has a seal fire first with much lower radiation levels, unless the roof sinks, in which case there may be some time to evacuate before maximum radiation levels.
The spacing doesn't appear to meet typical process safety guidelines for separation between flammables tanks and occupied buildings (e.g. thermal radiation criteria 5 kw/m2 for temporary buildings without shielded escape from Energy Institute Model Code Part 19 Fire Precautions at Petroleum Refineries and Bulk Storage installations).
A firewall would have to shield from the entire flame height to some calculated distance.
A fire-rated exit corridor may be an option provided it has sufficient capacity and terminates far enough away that the radiation level is below injury levels.
The safe level of thermal radiation is a function of the radiant heat and time.
I once did an analysis of escape from a temporary office portable building exposed by a large tank based on emergency egress outdoor travel speeds, radiation at various points along the path, and TDU (total thermal dose) that indicated potential pain level, but less than 1/2 of blistering level to bare skin (not accounting for the effect of clothing, or fire-retardant workwear. TDU = kW/m2^4/3*time(sec).
 
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