Twin Tower Fires Weren't Very Hot
Well, NIST itself says that paint tests indicated low steel temps -- 480 Fahrenheit -- "despite pre-collapse exposure to fire". NIST also said that microstructure tests showed no steel reached critical (half-strength) values of 600 Celsius (1112 degrees Fahrenheit) for any significant time.
In addition, Thomas Eager, a Professor of Materials Engineering and Engineering Systems at MIT and a defender of the official story, concluded that the temperatures in the Twin Towers never exceeded 800 Celsius (1472 degrees Fahrenheit). Eager pointed out that, contrary to popular belief, jet fuel from the planes did not increase the temperature of the fires.
Finally, 4 additional pieces of evidence are cited by Jim Hoffman to show low temperatures in the Towers:
(1) At least 18 survivors evacuated from above the crash zone of the South Tower through a stairwell that passed through the crash zone, and many more would have were it not for confusion in the evacuation process. None of the survivors reported great heat around the crash zone. An audiotape of firefighter communications revealed that firefighters had reached the 78th floor sky lobby of the South Tower and were enacting a plan to evacuate people and put out the "two pockets of fire" they found, just before the tower was destroyed.
(2) The fires were not hot enough to produce significant window breakage in either tower. Window breakage is a common occurrence in large office fires, particularly when temperatures exceed 600° Celsius.
(3) Unlike the North Tower, in which some fires were visible well above the impact zone, the fires in the South Tower never spread beyond the impact zone. In fact there is no evidence that the fires on the floors at the impact zone even spread to the opposite side of the building. By the time the building collapsed, the fires appeared to be suffocating, as no flames were visible, and only black smoke was emerging. At that time the vast majority of smoke was coming from the North Tower.
(4) The fires did not cause parts of the building to glow. At temperatures above 700° C, steel glows red hot, a feature that is visible in daylight.See also this page.
The fires were not very hot. So why did the Twin Towers collapse?