The 9/11 Forum

Some guy from AE911Truth did a rather convincing experiment (at least so far as the 'ingredients' he tested with) showing that 'normal' building materials would not have contributed to sulfidation of steel. He introduced gypsum + concrete powder + aluminum + diesel fuel to an I-beam, and burned it for for many hours (it took days to cool).

http://911blogger.com/news/2010-07-13/911-experiments-mysterious-eutectic-steel

Hi Metamars,

I'm out of town most of the time of late so I have not been doing much 911 research these days. However, I did have a look at the video. I must say that I'm very impressed with Mr. Cole's experiment - nice job! It certainly looks convincing with regard to how the experiment was carried out and I'm very happy to see someone test something I suggested a few years ago.

I am prepared to admit that my initial proposal as to how steel was sulfided during the 911 events needs to be modified. Certainly it looks like diesel fuel, gypsum, concrete and aluminum alone are not going to do it .....

However, the one thing I would suggest that still makes "natural" sulfidation of steel a real possibility is the inclusion of chlorine in the experiment. Chlorine species would have been present in the WTC fires from the thermal degradation of the very common plastic PVC which is used in many office building items such as flooring tiles, electrical insulation, TV and computer housings, window blinds, plumbing fixtures, etc, etc.

The combustion of PVC releases copious amounts of the very corrosive gas HCl which attacks even stainless steel. HCl and Cl2, alone or in combination, are also known to have a catalytic effect on high temperature steel corrosion that would leave affected areas of steel very vulnurable to subsequent sulfide attack. The type of accelerated corrosion I am referring to has been observed in the gaseous effluent streams of industrial and municipal waste incinerators. So regrettably, before anyone claims victory on this question, I would say that the experiment needs to be repeated with PVC thrown into the mix.

Unfortunately, I'm not allowed to post on 911Blogger, but perhaps you could convey these comments to those guys.

Thanks,

Frank

Metamars:

As a follow-up to my last post, here is some supporting information on PVC and HCl/Cl2 in fires:

Thermal Degradation of PVC and the Fate of HCl Emissions

The thermal degradation of pure PVC and PVC blended with plasticizer and other additives has been extensively studied for a wide range of formulations heated in air, inert gases or under vacuum. Dehydrochlorination at ~ 300 °C is the dominant decomposition reaction for all formulations although the initiation temperature depends on the particular additives and may be as low as 250 °C. Nevertheless, the loss of HCl from PVC is invariably close to the theoretical maximum of 56.7 % of the sample weight for all formulations heated above 400 °C.

- [CHCl – CH 2 ] n - + Heat = - [CH = CH ] n - + n HCl

See for example: J. Polymer Sci. Vol 12, 737, (1974); Vol. 16, 3139, (1978); Vol. 18, 3101, (1980); Polymer Vol 25, 1337 (1984), etc.

HCl is an extremely corrosive and reactive gas. In fact it has been reported that the concentration of HCl in a fire involving PVC “decreases rapidly after its generation due to its consumption in reaction with almost all the surface of the building. Accordingly, the actual concentration of hydrogen chloride in the atmosphere of a fire accident involving PVC is far lower than the calculated value. For instance, some reports say that the hydrogen chloride concentration is about 10% of the calculated value in a fire involving PVC made cable insulator.”
(See http://www.vec.gr.jp/english/library/fire/3.html).

In the case of the fires in WTC 1 & 2, HCl was released not only from the electrical wiring but also from PVC-based plastics in materials such as flooring tile, window blinds, TV monitors, etc, present in the workstations on the fire-affected floors. NIST NCSTAR 1-5C states that plastics accounted for about 20 % of the combustibles in a typical workstation. Given that PVC is one of the most widely used plastics, I would estimate that there was at least 3 tonnes of PVC on every WTC floor in addition to the PVC in the electrical wiring. Thus as much as 2 tonnes of HCl was available to react with exposed surfaces on the fire-affected floors in WTC1 & 2.

HCl reacts with zinc, copper and iron, forming the corresponding chloride and liberating hydrogen gas:

Zn + 2HCl = ZnCl2 + H2

Cu + 2HCl = 2CuCl + H2

Fe + 2HCl = FeCl2 + H2

Secondary reactions also occur:

FeCl2 + HCl = FeCl3 + ½ H2

Fe2O3 + 6HCl = 2FeCl3 + 3H2O

Studies, (See for example Oxidation of Metals 26, 157, (1986)), have shown that the formation of ferric chloride, FeCl3, is favored by the presence of oxygen via the reactions:

2HCl + ½ O2 = Cl2 + H2O

2FeCl2 + Cl2 = 2FeCl3
Or the reaction:

Fe + 3HCl + ¾ O2 = FeCl3 + 1½ H2O

In the present context the most significant feature of the chlorides of zinc, copper and iron is that they have low melting and boiling points, (See Table 1), and are therefore very mobile.


Table 1. The Melting and Boiling Points of Some Zinc, Copper and Iron Chlorides

Species Melting Point (°C) Boiling Point (°C)
Zn 420 908
ZnCl2 275 765
Cu 1083 2582
CuCl 430 1463
Fe 1539 2887
FeCl2 677 1026
FeCl3 304 319

Because the metal chlorides listed in Table 1 have significant vapor pressures above their melting points, exposure of specimens of iron, zinc or copper to HCl at temperatures above 400 °C results in substantial weight loss through vaporization of the metal chloride reaction product. Thus iron loses up to 600g/m2 per hour as volatile FeCl3 through exposure to HCl-air mixtures at 500 °C, (See Corrosion Science 21, 805, (1981)).

The Production of SO2 in the Fire-Affected Regions of the WTC:

While hydrochloric acid appears to have been the main corrosive agent in the fire-affected zones of the Twin Towers, the sulfidation of steel discussed in the FEMA Report and in NIST NCSTAR 1-3C suggest that sulfur-containing species also contributed to the wastage of metals in these buildings. Live load materials that were present in the WTC would be very similar to the materials found in offices or dwellings in any modern urban environment. In fact, researchers investigating airborne particulate over New York City in October 2001 observed that the plume of smoke and dust released during the WTC disaster “resembled in many ways those seen from municipal waste incinerators”, (See T. A. Cahill et al. “Analysis of Aerosols from the World Trade Center Collapse Site, New York, October 2 to October 30, 2001.” Aerosol Science and Technology 38, 165, (2004)).

D. O. Albina et al. in the article “Effects of Feed Composition on Boiler Corrosion in Waste-to-Energy (WTE) Plants”, published in the 12th North American Waste to Energy Conference (NAWTEC 12), 2004, have studied the composition of flue-gases from the combustion of municipal solid waste, (MSW):

“The calculated flue-gas composition upon combustion of 1 kg (dry) NYC MSW was 7.4 % CO2, 11 % H2O and 7.2 % excess O2 and the balance N2 with 334 ppm HCl, 210 ppm, NO and 227 ppm SO2. These results are in relatively good agreement with flue-gas compositions obtained in the combustion chambers of present WTE facilities. Typical HCl concentrations in combustors were in the range 200 – 900 ppm while SO2 concentration were in the range of 10 – 300 ppm….. Concentrations of gaseous SO2 were observed to increase at 600 °C and to peak at 900 °C.”

Thus I would argue that the corrosion of iron, copper and zinc in the fire-affected regions of WTC 1 & 2 was dominated by the presence of HCl and SO2 produced by the decomposition of PVC, gypsum and other materials containing labile chlorine and sulfur species. I have also pointed out the similarity of the gaseous emissions from the WTC fires to the emissions from waste incinerators. This is very significant because high temperature corrosion of incinerators is a well-documented problem for heat transfer surfaces such as the boiler walls and super-heater, evaporator and economiser tubes made from low alloy steels.

P. Rademakers et al. in a report entitled “Review on Corrosion in Waste Incinerators and Possible Effect of Bromine”, issued in October 2002, (http://www.ebfrip.org/statements/TNO-AK ... -Final.pdf) note that:

“High temperature corrosion in waste incinerators is caused by chlorine, either in the form of HCl, Cl2, or combined with Na, K, Zn, Pb, Sn and other elements. In particular both gaseous HCl, with and without a reducing atmosphere, and molten chlorides within deposits are considered to be major factors. Sulfur compounds, which under certain circumstances are corrosive compounds themselves, can enhance or reduce the corrosion by chlorine…(depending on) the SO2 / HCl ratio.”

Of particular concern in waste incinerator operations is a type of corrosive attack known as “active oxidation”. A well-known example of this occurs in oxygen-starved regions exposed to HCl or Cl2 where volatile iron chlorides form and migrate away from the original reaction site. In regions exhibiting higher oxygen partial pressures, these chlorides are converted to oxides with the liberation of chlorine. However, the newly formed oxide does not form as a perfect layer and offers little or no protection to the underlying metal. Under these circumstances Cl2 can penetrate pores or cracks in the oxide/deposit and react with the metal to form more volatile chlorides. Thus we see that the chlorine is acting as a catalyst leading to enhanced corrosion:

Fe + Cl2 = FeCl2

4FeCl2 + 3O2 = Fe2O3 + 2Cl2

On the role of sulfur compounds during waste burning P. Rademakers et al. state:

“In waste incinerators deposit formation is one of the main reasons for corrosion at relatively low metal temperatures… (in the range of 250 to 400°C). Analyses of deposits have shown that outer scales contain mainly sulfates like CaSO4 , Na2SO4,, K2SO4 , ZnSO4 , PbSO4 . The inner scales near the metal surface show considerable amounts of chlorides like CaCl2 , KCl, ZnCl2 and PbCl2 . These salts are able to convert the protective oxide layers to complex oxy-chlorides .”

The presence of sodium and potassium salts in waste incinerator deposits is noteworthy and stems from the fact that alkali metals, and in particular potassium, are enriched in the organically bound metallic elements that are organically bound or dissolved in salts in wood or wood derived products such as paper and cardboard (See for example, T. R. Miles et al. in “Alkali Deposits Found in Biomass Power Plants”, NREL Report, April 1995). Research presented in a paper entitled “Aerosols in Fixed –Bed Biomass Combustion”by I. Oberberger presented at a Bio-energy Conference in October 2003, shows that the aerosol concentration in the flue gas from burning biomass increases with increasing concentrations of K, Na, Zn and PB in the fuel.

Table 2 provides some data on chloride – sulfate mixtures with particularly low melting points.

Table 2. Low Melting Point Chloride – Sulfate Mixtures

Salt Mixture with wt % of each Component Melting Point (°C)
60 ZnCl2 + 34 FeCl3 200
ZnCl2 + KCl + ZnSO4 + K2SO4 226
68 ZnCl2 + 32 KCl 230
84 ZnCl2 + 27 PbCl2 262
ZnCl2 + ZnSO4 300
35 FeCl2 + 47 KCl 355


The very low melting point of ZnCl2–based salt mixtures accounts for the poor corrosion resistance of galvanized steels to high temperature environments containing HCl or Cl2. Indeed researchers in the U.K. have developed a process for the removal of the zinc coating on galvanized steel scrap metal using air containing 10 % gaseous chlorine at 800° C. (See the article by J.K.S. Tee et al. in the Journal of Metals 51, 24 (Aug 1999)). These authors report over 90 % removal of the zinc on a specimen of electro-galvanized steel after only 10 minutes of exposure to the 10 % Cl2 / air gas mixture. Interestingly, the same authors have patented a process for zinc removal utilizing the combustion of waste PVC as the source of chlorine.

An analysis of the thermodynamics of metal chlorides and sulfates shows that, in addition to zinc, copper and lead may be mobilized under the conditions prevailing in solid waste incinerators. (See: J. of Mat. Cycles Waste Manag. 4, 143 (2002) and Envi. Sci. & Tech. 30, 50, (1996)). In the case of copper it appears that the degree of volatilization is strongly dependent on the CO/CO2 ratio. Under reducing conditions, (CO/CO2 ³ 0.1), 100 % volatilization of copper is predicted at temperatures of 800° C or higher. Similar behavior is expected for lead at temperatures above 500° C with no sulfur species in the system, or 800° C under conditions favoring sulfate formation.

Metamars:

Just two more points:

1. It is interesting to note that the surface analytical data presented by S. W. Banovic in NIST NCSTAR 1-3C show that for the single column sample K-16, chlorine was the most abundant species (after iron of course!), and was generally HIGHER than the much debated sulfur. And if you look at the USGS Particle Atlas Table of XRF analyses for concrete particulate in WTC dust, more than 50 % showed the presence of chlorine. This chlorine cannot be indigenous to the concrete since chloride ion is specified to be less than 200 ppm in concrete because of its deleterious effects on this material.

2. The NIST Report NCSTAR 1-5 provides data for plastic materials in a typical WTC workstation. This data indicates that there was about 1.5 tonnes of PVC derived chlorine per floor. This estimate actually ignores the contribution from PVC in the vinyl asbestos tiles used in the WTC flooring. This amounted to about 0.3 tonnes per floor. That's a lot of chlorine!

Dr G.

Interesting chemistry. However why would the chemical attacks be concentrated at the joints/ends of the steel recovered? Why would this be concentrated and not attack more of the steel?

The problem seems to be that whatever attacked the steel chemically does include the chemicals you mentioned. And what do you, there aren't too many other chemicals to consider.

The columns and beams were encased in fire protection and the twins columns had 3" thick gypsum blocks encasing them. You can see some of them in the debris.

If sulfur and chlorine attacked the steel, perhaps they were put where someone wanted the steel weakened?

And would we expect the gases to be flow down wind? Why would they all migrate and hang around the ends of steel beams and columns?

And finally if what is burned incinerators is such a toxic chemical how are steel elements of the incinerators not attacked to the point were they need to be constantly be replaced? Whatever happened to the WTC steel in WTC 2 took about an hour WTC 1 slightly longer and WTC 7's burn times are still shrouded in mystery. But such short burns of open air uncontrolled combustion seems unlikely to produce the thoroughness of the attack of the recovered steel.

You may have the chemistry correct, but I think you are in tin foil territory as to the source. Even if there were 2 tons of PVC on a floor - its spread over 30,000 SF and not all of it was burning and what did burn did not all burn in one short instant.

If office fires in high rise steel structures produced that in 1 hr, what about Madrid and the other well known office high rise fires... where is the sulphur attacked steel? Answer: no where to be found.

SanderO wrote:why would the chemical attacks be concentrated at the joints/ends of the steel recovered?

Perhaps because the process occurred post descent, where column ends would be more likely to come to rest in *pools* of available compounds ?

I think you are in tin foil territory as to the source.

Given the excellent quality of Dr. G.'s analysis, I think this an unwarranted and rather rude inclusion in your post.

If you can respond in a similar level of technical detail, then you earn wider lattitude. In this case it looks more like hand waving. Get the textbooks out.

If office fires in high rise steel structures produced that in 1 hr, what about Madrid and the other well known office high rise fires... where is the sulphur attacked steel? Answer: no where to be found.

Where is the PVC in that building ?

According to Dr G and I concur that PVC is a rather common substance today in all home and office environments it goes to reason that the WTC chemical mix was not especially different, although it was alleged to be asbestos rich.

I am not a chemist and I am impressed by Dr. G's post, but notwithstanding all the references the underlying thinking seems flawed to me - and so I used the term tin foil territory. It wasn't intended as an insult, so if anyone is offended by this language I apologize. I can't respond on a similar level of detail because it is outside my expertise as an architect.

I, for one am not impressed by presentations which I cannot understand. But heck, go for it if it reveals the truth about what happened.

There is some of fixing the facts around the "policy" I sense from all sides in the 9/11 debate. But this is understandable as forensic researchers here are largely starved for data (some of it denied and held by the government - NO FAIR!). The sulfidation of the steel seems to have confounded almost everyone as it's probably never been seen after steel has been in an office fire for a few hours. Jon Cole's experiment was the first part of demonstrating that most of the chemicals present would not produce the effect. I wrote to him suggesting he add sulfur and more heat for a few hours burn to see if he could reproduce it. He's only ruled out one set of conditions. Dr. G can send him a recipe and see what that produces.

Maybe Cole should toss in a whole bunch of electrical cables. It's unlikely that there was PVC pipe used in the WTC. They weren't using it in buildings at the time and it's not NYC DOB approved for piping or conduit. But there was wire and computer cases and office furniture etc. Two tons of pvc per floor might be a bit high and I would like to see how that number was derived.

Saying that the process occurred post descent also makes little sense (to me), though it's certainly possible. it appears more likely that sulfidation was contributory to structural failure than a consequence of it.

SanderO wrote:Dr. G can send him a recipe and see what that produces.

That would be a next step imo.

Maybe Cole should toss in a whole bunch of electrical cables.

And all manner of stuff, including (OLD) network cabling.

Saying that the process occurred post descent also makes little sense (to me), though it's certainly possible. it appears more likely that sulfidation was contributory to structural failure than a consequence of it.

Why ? There has to be a specific reason for it NOT to have occured post descent to have that position. Post descent is *possible* and would potentially explain the focus.

If it occurred post decent this type of steel should have been found at all three collapses, or even at WTC 5 and 6 where there were collapses and files and the same soup of chemical.

Most high rise fires never reach the stage of collapse so post collapse processes is also something rather not well documented. So sure the buildings fell and some weird chemistry began down there where the NASA images show it was extremely hot.

So the same sulfidation of steel was found under all three buildings?

SanderO wrote:So the same sulfidation of steel was found under all three buildings?

No idea. Anyone ?

Dr. G wrote:Hi Metamars,

I'm out of town most of the time of late so I have not been doing much 911 research these days. However, I did have a look at the video. I must say that I'm very impressed with Mr. Cole's experiment - nice job!

Thanks very much for checking in. I posted most of your first response at 911blogger, and linked back to here. I also requested that they reconsider their having banned you.

Best,
metamars

Dr. Greening, I think one can see how HCL could cause corrosion, but it is hard to see how it could cause intergranular melting, at about 1,800 degrees F due to a eutectic formation.

Although you show sulfur compounds to be present I don't see where you fully explain the actual chemical mechanism by which you believe the observed sulfidation and any subsequent formation of a eutectic could be caused.

Well, as far as I understand it calcium sulphate alone is not gonna to do it, of course you need some kind of reducing agent like carbon to generate sulphur dioxide.

So, the ultimate mistake in my point of view is that he did not mixed in enough carbon (am I missing something?), the fuel he added surely vaporised quickly and escaped the box, while the amount of plastic he added was way too small.

I don't think that some kind of HCl assisted corrosion would do much, as some people are burning coal with high sulphur content and PVC in their stoves for years without any significant holes.

Anyway, I would repeat the experiment with PVC, carbon and pure sulphur.

EDIT: Dr.G, are you able to carry out some experiments?

A eutectic formation is something which has a lower melting point than any of the components? Is that true?

Is there a claim that some soup of chemicals associated with the steel lowered its melting point or shifted its strength characteristics relative to its temperature?

SanderO wrote:A eutectic formation is something which has a lower melting point than any of the components? Is that true?

Is there a claim that some soup of chemicals associated with the steel lowered its melting point or shifted its strength characteristics relative to its temperature?

A good example of a eutectic is tin/lead solder. The lowest possible melting point of any alloy combination of tin and lead occurs with approximately 62% tin and 38% lead. That temperature is 361 degrees F (183 degrees C). If the percentage, by weight, of either the tin or lead is changed in either direction the melting temperature is greater than 361 degrees F. Individually both lead and tin have higher melting temperatures than 361 degrees F, with pure tin melting at about 450 degrees F (232 degrees C) and pure lead at 621 degrees F (327.5 degrees C).

Here is an image of the phase diagram of tin/lead solder where you will see the low melting point occurs at the percentage of each constituent shown above and that at all other combinations it is higher http://www.ami.ac.uk/courses/topics/024 ... dex.html#2.

The FEMA Appendix C report says the melting of the steel piece they examined occurred at approximately 1,800 degrees F, which is a full 900 degrees below the point where steel would normally just begin to melt. The authors of Appendix C say it was a eutectic formation which included sulfur that caused the melting point to be lowered.

Interestingly, it is known that the addition of sulfur to thermite produces a eutectic reaction with steel, causing it to melt at a lower temperature. Here is a link to an objective look at this by a chemical engineer http://www.journalof911studies.com/volu ... emistryWTC