The simple facts of temperatures:

* 1535ºC (2795ºF) - melting point of iron
* ~1510ºC (2750ºF) - melting point of typical structural steel
* ~825ºC (1517ºF) - maximum temperature of hydrocarbon fires burning in the atmosphere without pressurization or pre-heating (premixed fuel and air - blue flame)

Diffuse flames burn far cooler.
Oxygen-starved diffuse flames are cooler yet.

The fires in the towers were diffuse -- well below 800ºC.

Their dark smoke showed they were oxygen-starved

steel melts at a temperature of 2,750 degrees Fahrenheit, but jet fuel burns at only 1,517 degrees F, if you want the place i got this information id be glad to give it to you