Col wrote:
"The Natural Philosopher" wrote in message
...
Brian Morrison wrote:
On Thu, 10 Sep 2009 08:31:08 +0100
"Col" wrote:

"Brian Morrison" wrote in message
k...

If any fire protection material that could cope with an airliner
collision at full speed exists, I would be surprised. The WTC had
sprayed on material on the steel beams, naturally such stuff is fairly
crumbly and works by ablating and taking heat with it. It isn't
mechanically strong.
Such fire protection does exist.
It's called 'intumescent paint'.
Does it still work when the paint is covered in burning jet fuel and
the temperature is 1000 degrees C?

yes, for a time.

Ultimately all fire protection of steel is about the insulating of the
structure, and the energy used to sublimate the coating..but eventually, a
fire hotter than the melting point of steel, will destroy the steel. You
can buy time, but not prevent failure.

A hydrocarbon fire will not reach the melting point of steel,

Odd that, since a bessemer converter is wholly carbon fuelled, and is
used to melt steel.

And in fact all steel is traditionally made using carbon fuels.


which is around1500C. Burning jet fuel will reach about 1100C.

Yeah sure, that's why they use special alloys in the exhaust of jet
engines.reheat gets up to a lot more than you might think. The
temperature is a function of the air blast I suppose, and a tall
building with a nice service area chimney can create quite a blast..

I suppose an oxy acetylene welder isn't a hyrdocarbon fuel fire
either..sure melts steel tho.



That said, getting close to the melting point isn't really all that
important. At 550C, steel has half the strength it has at room
temperature and this temperature is taken as the 'time to failure'
for determining the fire rating for intumescent coatings.


Exactly.


Col