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Old 01-11-2011, 07:41 PM
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Pete VanderLaan Pete VanderLaan is offline
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Steel "fails" at 800F which is not very hot. Those were the numbers we always used in the fire service to determine whether a steel beam was no longer viable. Also keep in mind that at those temperatures as it gets hotter, it expands almost ten percent, which is huge. A car on fire under an overpass can destroy the overpass if the I-beams are not insulated from the heat. If there is pre or post tensioned concrete in a heated situation, where the steel cable in the concrete can heat to that level, the steel fails and then so does the concrete because it's no longer in tension.

The cold face of a three inch refractory casting is going to be a lot hotter than 800F.
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