Sulfidated Steel in WTC 7

The eroded, sulfidated steel from WTC 7 at the scrapyard before it was cut off and taken for testing.

John Gross, who represented NIST on the FEMA Building Performance Study, poses next to the eroded, sulfidated steel. NIST would later claim that no identifiable steel was recovered from WTC 7, and John Gross would deny the existence of molten metal. ■ NIST’s next claim is simply false. It is impossible for a diffuse hydrocarbon fire to reach temperatures close to the 1,482°C (2,700°F) required to melt steel, particularly in an oxygen-starved debris pile.

■ Finally, with the expression “Any molten steel in the wreckage,” NIST neither confirmed nor denied the existence of molten metal. In an investigation that followed NFPA 921, NIST would have sought to establish whether molten metal was present and, if so, what its source was.

However, outright denial would be the approach used by NIST investigator John Gross. In a talk at the University of Texas in October 2006, he responded to a question about the presence of molten metal with the following answer:

First of all, let’s go back to your basic premise that there was a pool of molten steel. I know of absolutely nobody, no eyewitness who has said so, nobody who’s produced it. I was on the site. I was on the steel yards. So I don’t know that that’s so. Steel melts at around 2,600°F. I think it’s probably pretty difficult to get that kind of temperatures in a fire.5

In a New York Times article published in February 2002, James Glanz and Eric Lipton wrote:

Perhaps the deepest mystery uncovered in the investigation involves extremely thin bits of steel collected…from 7 World Trade Center…. The steel apparently melted away, but no fire in any of the buildings was believed to be hot enough to melt steel outright…. A preliminary analysis at Worcester Polytechnic Institute [WPI]…suggests that sulfur released during the fires—no one knows from where—may have combined with atoms in the steel to form compounds that melt at lower temperatures.6

The WPI professors, who were “shocked” by the “Swiss cheese appearance”7 of the steel, reported their analysis in Appendix C of the FEMA Building Performance Study, making the following recommendation:

The severe corrosion and subsequent erosion of Samples 1 and 2 are a very unusual event. No clear explanation for the source of the sulfur has been identified…. A detailed study into the mechanisms of this phenomenon is needed….”

A simple explanation for the source of sulfur, as well as the high-temperature corrosion and erosion, is “thermate,” which is produced when sulfur is added to thermite. In Revisiting 9/11—Applying the Scientific Method, Dr. Steven Jones explains:

When you put sulfur into thermite it makes the steel melt at a much lower temperature, so instead of melting at about 1,538°C it melts at approximately 988°C, and you get sulfidation and oxidation in the attacked steel….

The thermate reaction proceeds rapidly and is in general faster than basic thermite in cutting through steel due to the presence of sulfur.

How did NIST respond to FEMA’s recommendation?

First, NIST ignored it — thus ignoring what the The New York Times called “perhaps the deepest mystery uncovered in the investigation.”

Second, NIST claimed that no identifiable steel was recovered from WTC 7, providing the following answer in its WTC 7 FAQs:

Once [debris] was removed from the scene, the steel from WTC 7 could not be clearly identified. Unlike pieces of steel from WTC 1 and WTC 2, which were painted red and contained distinguishing markings, WTC 7 steel did not contain such identifying characteristics.

Third, when asked at NIST’s WTC 7 Technical Briefing on August 26, 2008, whether NIST had tested “any WTC 7 debris for explosive or incendiary chemical residues,” NIST lead investigator Dr. Shyam Sunder replied: