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Design Temperature Vs Fire Case


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#1 Ibnu84

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Posted 22 October 2015 - 02:06 PM

Hello All,

I have a drain system to collect oil leakage from our electrical transformer room.  The maximum oil temperature (operating) in the transformer circuit is 90 deg C and the drain pipe is designed for 100 deg C.  The drain pipe is made of GRE (Glass Reinforced Epoxy).  The drain sump is provided with a liquid seal to prevent fire propagation through drain system.

When there is a nearby fire, the transformer oil could catch fire and the oil would flow through the drain system. The question is: should I consider a design temperature for the drain pipe considering the burning oil temperature?  The flash point of the transformer oil is around 150 deg C.  If this to be considered, the GRE pipe cannot be used for the drain system.  Please advise.



#2 latexman

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Posted 22 October 2015 - 02:12 PM

When something has happened in the past, it is considered a credible scenario.  It is RAGAGEP to design for credible scenarios.

 

Transformer oil fires have happened in the past.



#3 Ibnu84

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Posted 22 October 2015 - 02:20 PM

Latexman,

If we take an example for determining design temperature of flare system, we normally do not consider fire relief temperature for the flare pipe design temperature. But it seems the transformer oil case above is not similar to fire relief case, isn't it?

#4 latexman

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Posted 23 October 2015 - 04:12 AM

I would prefer to stay on task with post #1 to explain my response more clearly.  We don't have all the details, such as how big is this drainage system, does it go underground, does it pass over flammable or combustible materials, does it pass over bodies of water, does it pass over occupied areas, etc.  Without intimate knowledge, one will probably get conservative answers.  Thus, I can't see using a combustible pipe material in an unfamiliar service that might have to flow burning transformer oil.  My response was more on your last sentence in post #1 than design temperatures.



#5 Ibnu84

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Posted 23 October 2015 - 06:07 AM

Hi Latexman,

Thanks for your reply. This is an offshore installation. Below transformer room is provided with drip pan with gulley and liquid seal. The seal is made of carbon steel. The GRE part is downstream of the seal. Though the fire is trapped in the seal, but the oil would still flow by gravity to the drain tank located at the lowest deck. It does not pass over bodies of water

Edited by Ibnu84, 23 October 2015 - 06:12 AM.


#6 fallah

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Posted 23 October 2015 - 07:33 AM

ibnu84,

 

The decision to consider the possibility of fire case happening is totally left to the user...

Anyway, you haven't to take fire case temperature as design temperature of the drain pipe; nevertheless it's better to consider CS material for drain pipe instead GRE...



#7 Neelakantan

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Posted 25 October 2015 - 05:10 AM

again limited information getting limited (limited in the content) responses;

 

you have not mentioned why GRE is used originally; can I hazard to guess that this drain system services other materials in the offshore installation (rig? fpso? ) including produced salt water; may I also hazard to guess that transformer oil drain may occur occasionally during maintenance, when the temp will be ambient? and that regular normal drain materials would be different from oil? and that GRE is decided to fight corrosion with exposure due to marine environment?

 

without these information, the responses will be, as I say, limited

 

regards

neelakantan

 

(PS: in offshore design, we tend to have open drain, closed drain and hazardous chemical drain; which type is this? open drain?)






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