Heat transfer through pipe in floor

[VTMEFPE]

I've just gotten a problem that is straightforward but could use some help in documentation. A 12-inch, schedule 40 pipe sleeve penetrates a 10-inch thick concrete floor in an inaccessible part of a 40-year old plant. The question is what is the threat to the room above if a fire below impinged upon this sleeve, which is capped on both ends by steel plates, roughly 1/2" thick. We assume there is nothing in the sleeve. Does anyone know of a good coefficient of heat transfer for "old" concrete? Has anyone had a reason to set up a heat transfer similar to this? It would seem to me the argument could be made the top of the pipe would be nearly as hot as the bottom within 15-minutes or so, but if anyone has any experince before I try to model it it'd be very welcome. And I am definitely not an expert at heat transmission in and spalling of concrete, but I can tell you the floor/ceiling currently looks healthy with no signs of pitting, etc.

 

[racookpe1978]

The pipe is vertical?

Capped both below and above, but the fire is assumed below the concrete floor burning continuously, right?

Fire temperature = wood or oil-fed or coal-fed? Or something vaporously explosive like acetone or gasoline naptha?

What thickness concrete?

Is the lower room vented anywhere into the upper room? Stairwell, other openings NOT blocked off, ladders, pipe racks, cable runs, elevator openings?

How close is the nearest "thing" to the 1/2 plate covering the upper hole in the pipe? (For example: The lower plate gets to 1200 F by being in the flames for a long time. The bottom of the pipe is 1000 F, the middle is 400 F, and the upper plate stabilizes to 200 F. The closest "thing" is a motor breaker 24 inches away. The upper plate is too cool to hurt the breaker in any reasonable time.

 

[VTMEFPE]

RA Cooke, you're probably getting a little more indepth than I was going to. The floor is 10" of healthy concrete, and each room is fiarly well-sealed. What I was really interested in figuring was the first 15 or 20 minutes of heat transfer. So, assuming an oil pool fire below that impinges upon the pipe sleeve, how hot could the top of the pipe get before a fire brigade would be spraying water on it? The brigade should have responded within 15 minutes.

My largest gap of knowledge for a problem of this sort is how well the concrete floor would insulate or dissipate the heat conducting through the pipe. The target of the heat rising off the pipe coudl change. For instanceif it was determined the top of the pipe could get to 500F within 15 minutes I would not allow boxes anywhere near it on the floor above.

Thank you.

 

[IRstuff]

I think it's just basically going to get somewhat warm to the touch. Air is not that good a conductor. Concrete is, by at least factor of 3, a better thermal conductor. I'd be more concerned about the concrete getting hot. 10" of concrete will conduct about 200W/ft^2 for a 1500F temperature difference. Your sleeve full of air will transmit about 10W.

TTFN
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