World Trade Center Building Fire 09/11/2001
Previous WTC Fire: February 13 1975 World Trade Center One Fire
Previous WTC Bombing: 1993 World Trade Center Truck Bomb
8:46AM: American Airlines Flight 11 Impacts North Tower
8:57AM: Jet Fuel in North Tower (WTC1) Burns Up
9:03AM: United Airlines Flight 175 Impacts South Tower
9:13AM: Jet Fuel in South Tower (WTC2) Burns Up
"The initial jet fuel fires themselves lasted at most a few minutes.” [National Institute of Standards and Technology, 9/2005, pp. 183 pdf file]
Engineering professor Forman Williams will say the jet fuel “burned for maybe 10 minutes.” [Popular Mechanics, 3/2005]
FLIR Image of WTC2 15 Minutes After Impact irinfo.org
Flight 11, a Boeing 767, had a fuel capacity of 23,980 gallons, but was only carrying about 10,000 gallons when it hit the WTC. NIST will estimate that less than 1,500 gallons were consumed in a fireball inside the tower and a comparable amount was consumed in the fireballs outside the building. Therefore, approximately 7,000 gallons splashed onto the office furnishings and started fires on various floors. However, after the jet fuel is used up, office fires burn until the building collapses. NIST will calculate that there were about four pounds per square foot of combustibles in the office space, or about 60 tons per floor. Offices in the WTC actually have fewer combustibles than some other similar spaces due to the small number of interior walls and limited bookshelf space. NIST will later find that only three of sixteen perimeter columns it recovers reached a temperature of 250°C and neither of the two core columns it retrieves reached this temperature. NIST will also find that none of the samples it acquires reaches a temperature above 600°C (see August 27, 2003). Although steel does not melt until its temperature is about 1,600°C, it may begin to lose significant strength at over 500°C. [National Institute of Standards and Technology, 9/2005, pp. 20, 29, 24, 77 pdf file]
"The fire is the most misunderstood part of the WTC collapse. Even today, the media report (and many scientists believe) that the steel melted. It is argued that the jet fuel burns very hot, especially with so much fuel present. This is not true.... The temperature of the fire at the WTC was not unusual, and it was most definitely not capable of melting steel. In combustion science, there are three basic types of flames, namely, a jet burner, a pre-mixed flame, and a diffuse flame.... In a diffuse flame, the fuel and the oxidant are not mixed before ignition, but flow together in an uncontrolled manner and combust when the fuel/oxidant ratios reach values within the flammable range. A fireplace is a diffuse flame burning in air, as was the WTC fire. Diffuse flames generate the lowest heat intensities of the three flame types... The maximum flame temperature increase for burning hydrocarbons (jet fuel) in air is, thus, about 1000 °C -- hardly sufficient to melt steel at 1500 °C. But it is very difficult to reach this maximum temperature with a diffuse flame. There is nothing to ensure that the fuel and air in a diffuse flame are mixed in the best ratio... This is why the temperatures in a residential fire are usually in the 500 °C to 650 °C range. @@It is known that the WTC fire was a fuel-rich, diffuse flame as evidenced by the copious black smoke.@@" tms.org
"Annealing studies on recovered steels established the set of time and temperature conditions necessary to alter the steel microstructure. Based on the pre-collapse photographic evidence, the microstructures of steels known to have been exposed to fire were characterized. These microstructures show @@no evidence of exposure to temperatures above 600C for any significant time.@@ Similar results, ie., @@limited exposure if any above 250C were found for the two core columns recovered from the fire-affected floors of the towers@@, which had adequate paint for analysis." NIST.gov_pxli
(9:50 a.m.) September 11, 2001: Molten Metal Pours from South Tower
Molten metal pouring out of the side of the World Trade Center.Molten metal pouring out of the side of the World Trade Center. [Source: Cameraplanet]Video footage later reveals that in the minutes immediately before the collapse of the WTC’s South Tower, a stream of molten metal starts pouring out of a window opening around the northeast corner of its 80th floor. FEMA later suggests that this is “possibly aluminum from the airliner,” and comments, “This is of particular interest because, although the building collapse appears to have initiated at this floor level, the initiation seems to have occurred at the southeast rather than the northeast corner.” [Civil Engineering, 5/2002; Federal Emergency Management Agency, 5/1/2002, pp. 2-34; Dwyer and Flynn, 2005, pp. 207] According to the National Institute of Standards and Technology, “The composition of the flowing material can only be the subject of speculation, but its behavior suggests it could have been molten aluminum.” [Pitts, Butler, and Junker, 9/2005, pp. 375] However physics professor Steven E. Jones will in 2006 dispute this, saying that molten aluminum is silvery and never turns yellow, like what is in the video footage. He will instead claim the presence of this molten metal supports the theory that explosives, specifically thermite, are what caused the Twin Towers to collapse. He says thermite can cause steel to melt and become yellowish. [Deseret Morning News, 4/10/2006]
From Federal Building and Fire Safety Investigation of the World Trade Center Disaster
Page 52, E.8.2 Characteristics of the Fires
The dominant fuel for the fires in the towers was the office combustables. On the floors where the aircraft fuselage impacted, there was a significant, but secondary contribution from the combustables in the aircraft. Most of the jet fuel in the fire zones was consumed in the first few minutes after impact, although there may have been unburned pockets of jet fuel that led to flare-ups late in the morning.
Page 53, E.8.3 Capability for Large Fire Reconstruction
Jet fuel sprayed onto the surfaces of typical office workstations burned away within a few minutes. The jet fuel accelerated the burning of the workstation, but did not affect the overall heat released.
Page 104, 3.2.1 Nature of Combustables
While much of the public attention has been focused on the jet fuel, most of this was combusted in only a few minutes.