The Truth of Thermite & Leapfrogging

[johnny karate]

metamars, please tread lightly. If you get William of Ockham spinning in his grave any faster, it'll knock the Earth out of orbit and send us careening into the sun.

 

[Cl1mh4224rd]

I love the idea of vermiculite fireproofing adhering to the burning super thermite! And creating some impenetrable wall of solid fireproofing, keeping the hot side hot and the cool side cool.

Metamars, have you ever seen structural fireproofing? If you had done so, you might imagine why your idea is pure looney tunes.

Yep. It's a horribly retarded notion at best.

The fireproofing would begin falling away as soon as the nano-thermite began reacting, considering it no longer has anything to "stick" to. Once that happens, the majority of the energy from the nano-thermite reaction is allowed to escape relatively harmlessly into the air.

 

[fourtoe]

Update...I was on a We Are Change LA channel and they banned me shortly after bringing these issues up and the differences between a CD & the WTC...shocking I know.

Oh wacLA, you loved my crashing your 9-11 protest rally, then crashing the 10-11 protest rally, oh how you shall love my attending the 11-11 protest rally you are holding next week. This time, I'll record everything.

wacLA are crazy, they claim that AQ doesn't exist on their site...

 

[grandmastershek]

I've patented picothermite and femtothermite with all rights and privliges therein. It uses a 1500W hair dryer and only a hair dryer, as an ignition source. Time delay is accomplished by varying combinations of "hi", "lo", "style" and "volumize" settings. Great stuff for all your demolition needs.

????

 

[grandmastershek]

Oh wacLA, you loved my crashing your 9-11 protest rally, then crashing the 10-11 protest rally, oh how you shall love my attending the 11-11 protest rally you are holding next week. This time, I'll record everything.

wacLA are crazy, they claim that AQ doesn't exist on their site...

excuse my noobness, AQ?

 

[Brainache]

excuse my noobness, AQ?

Al Qaeda.

 

[grandmastershek]

Al Qaeda.

ahhh yes, and we didn't got to the moon either.

 

[TruthersLie]

Sharks with friggin laser beams!

no no no
super duper nano mothra

 

[grandmastershek]

no no no
super duper nano mothra

PFFFT! The space beam nutters got it all wrong. Sharks with laser beams were in the Hudson River! It's a historical fact!

http://query.nytimes.com/gst/abstract.html?res=9906E0D81E3BE033A25754C1A96E9C94659FD7CF

 

[Dave Rogers]

Kindly tell us, Dave, what you think would happen if 3.7 mm layer of non-explosive nano-thermite was placed on the outside of one side of a load-bearing column (say loaded to 50% of capacity), and then 2 inches of vermiculite fire-proofing was placed around that, and the nanothermite ignited. (I don't remember what column thickness I used for my 3.7 mm calculation. Figure a 'typical' thickness of columns at the impact level in WTC 1).

Bugger all, I suspect. I haven't done the calculations, but at a rough guess I'd say the thermite would at most supply enough energy to melt about 2mm of steel on one side of the column. However, this energy would not be transferred particularly efficiently into the steel, and would be conducted away from the surface 2mm to some extent. Overall, then, the result would be to warm the column a little.

What it would not do is cause the abrupt failure of the structural element with the millisecond-level precision of timing that most proponents of controlled demolition cite as their primary piece of evidence for the presence of an external source of collapse initiation. In particular, it would be useless for suppression of Tony Szamboti's much discussed missing jolt.

The physical principle that I do understand, and that you would do well not to forget, is conservation of energy.

You can waffle on about temperatures and thermal conductivities, make no mention whatsoever of energy densities and specific heats, and then make a statement like this????

Have you no sense of shame?

Dave

 

[Dave Rogers]

OK, let's do some actual energy calculations, rather than ignoring the conservation of energy and pretending that temperatures are all that matters.

I'll work with volumes rather than masses, so we can convert to metamars's 3.7mm layer easily. Thermite has an energy density of 18.4kJ/cc, so we can estimate nanothermite's energy density at about 7.4kJ/cc. That's all the energy we have to work with; conservation of energy, remember?

For a rough estimate of the specific and latent heats of steel, let's use iron; it's not going to be far wrong. The specific heat is about 3.5J/ccK, and the latent heat of fusion is about 2.1kJ/cc. Assuming a melting point of 1370K, we need to heat the steel by about 1070K before melting it. That requires about 3.7kJ/cc. Add another 2.1kJ/cc to melt it, and we have an energy requirement of 5.8kJ/cc to melt steel from room temperature.

Sounds like thermite can melt just over its own volume of iron. But wait; it needs to raise itself to the same temperature. I don't have a figure for the specific heat of thermite, but let's guesstimate it as about half of the specific heat of iron (thermite is about half the density of iron; I'll pass over the fact that the specific heat of aluminium is higher) and add another 1.8kJ to the energy requirements. That gives us 7.6kJ/cc, or roughly the amount of energy we started with.

Therefore, if we could somehow obtain perfect heat transfer between the nanothermite and the steel, with no heat going anywhere else, and also obtain perfect insulation between the outer 3.7mm of steel and the remainder of the column, then metamars's 3.7mm of nanothermite would melt away the outermost 3.7mm of the column. That requires that it has no effect whatsoever on the remainder of the column.

The corner columns at the 97th floor were I-beams with 3" flanges. Loss of 3.7mm from a 76.2mm plate will reduce its strength by 5%. Since the beam was initially loaded at 50% of capacity, it is now loaded at 52.5% of capacity. Global collapse does not ensue.

Of course, in real life, not all the energy from the thermite would transfer to the column, so this is a worst case scenario. Also, in real life, the heat conduction of the steel would result in even heating of the column flange rather than highly localised melting of one side. Assuming 7.4kJ/cc transferring into a volume 20 times that of the thermite, we get a total temperature rise of 105K over the entire flange of the column. This is not sufficient to cause significant reduction in structural strength of the steel. Again, global collapse does not ensue.

This is just a rough, back-of-the-envelope calculation, and I've been known to make mistakes on these things. I'd encourage anyone else who's interested to check my calculations. From a first look, though, it appears to me that 3.7mm of nanothermite applied to a core column and ignited will have negligible effect on the structural stability of the building.

Dave

 

[TruthersLie]

Dave.

How dare you debunk the super duper nano mothra. It is special, because it has the word NANO infront of it.

shesh... and you call your self a physicist...
You obviously need to go back to school and take the "evil super genius" classes where they teach you to warp the fields of reality.

 

[Myriad]

Meanwhile, interesting things would be going on at the thermite-vermiculite boundary. I'm assuming that Metamars is referring to expanded (aka annealed or exfoliated) vermiculite based on the thermal insulation value he's claiming, and also because raw vermiculite would expand dramatically when exposed to heat (that's how the expanded exfoliated vermiculite insulation material is manufactured), blowing the whole elaborate wrapping apart.

Since the vermiculite melts at a comparable temperature to steel, its insulating qualities become irrelevant (except to facilitate melting at the thermite-exposed surface) and due to its low density it would erode rapidly, releasing heated air in the process. The melted vermiculite is about one sixth the density of molten iron so expect violent fluid convection allowing the iron thermite product to rapidly displace downward. Best case is a loss of the better part of the thermal energy; that's if the whole thing doesn't just melt through at the base of each section and splash the thermite product all over the place, or blow apart if the outer wrapping has insufficient venting for the heated air.

All while the steel surface just sits there and laughs.

Engineering tip: using an insulating material that melts at over a thousand degrees C less than the temperatures you're trying to insulate = bad idea.

I would pay Broadway ticket prices to eyewitness a test of this scheme, say on a 10-foot vertical I beam loaded to 50% of its capacity.

Respectfully,
Myriad

 

[metamars]

Of course, in real life, not all the energy from the thermite would transfer to the column, so this is a worst case scenario. Also, in real life, the heat conduction of the steel would result in even heating of the column flange rather than highly localised melting of one side. Assuming 7.4kJ/cc transferring into a volume 20 times that of the thermite, we get a total temperature rise of 105K over the entire flange of the column. This is not sufficient to cause significant reduction in structural strength of the steel. Again, global collapse does not ensue.

Dave

Wow. So you think considering two extreme cases, and completely ignoring what, in a sense, could be considered to come between them, is a clever way to make a reasonable guess as to whether such a column would collapse?

I think not.... (We may be observing another case of debunker abortive thought processes!)

Even with simplyfying assumptions, I'm pretty sure a computer is needed to solve the heat equation, either for a box column or a flange column. Even if you considered the nanothermite an ideal heat source, which it's not.

In the meantime, you can take a look at this web page, which graphs the equilibrium solution of the 1-d heat equation, when one end of the rod is maintained at a higher temperature than the other. There's a linear drop off of temperature.

Please take another stab at this, Dave, but look beyond (i.e., at a later time) heat from the nano-thermite source magically not penetrating the steel column at a depth equal to that obtained by melting an outer layer. Also, consider what the temperature distribution would be like before complete thermal equilibrium is attained.

Yes, you need a computer to get an exact solution. Nevertheless, you should be able to make reasonable qualitative guesses.

 

[twinstead]

Yes, you need a computer to get an exact solution. Nevertheless, you should be able to make reasonable qualitative guesses.

Do you define "reasonable qualitative guesses" only as "stuff I agree with"?

 

[funk de fino]

Yes, you need a computer to get an exact solution. Nevertheless, you should be able to make reasonable qualitative guesses.

Why should anyone put any effort into your imaginary world scenario? It's impossible.

It's like asking someone to prove there are no fairies.

 

[Dave Rogers]

Wow. So you think considering two extreme cases, and completely ignoring what, in a sense, could be considered to come between them, is a clever way to make a reasonable guess as to whether such a column would collapse?

Let me just point out that that's two more cases than you've considered. It certainly seems to me that a better way to make a reasonable guess as to what happens in a heat transfer process is to consider heat transfer in some way, rather than simply talk about temperatures. You can't understand the difference between intensive and extensive variables, and you have the nerve to call my thought processes abortive?

Please take another stab at this, Dave, but look beyond (i.e., at a later time) heat from the nano-thermite source magically not penetrating the steel column at a depth equal to that obtained by melting an outer layer. Also, consider what the temperature distribution would be like before complete thermal equilibrium is attained.

Yes, you need a computer to get an exact solution. Nevertheless, you should be able to make reasonable qualitative guesses.

There is not enough heat present to cause significant weakening of the column, and the shortfall is about an order of magnitude. That's my reasonable qualitative guess, based on a consideration of the actual energetics of two bounding assumptions. At the moment, I'm way, way ahead of you as far as analysis of your scenario goes.

It's your theory. You do the hard work. You prove that there is any possible way that the amount of thermite you're proposing can weaken the column. At the moment, all you've done is give an impressive demonstration of laziness, ignorance and hypocrisy.

Dave

 

[W.D.Clinger]

In the meantime, you can take a look at this web page, which graphs the equilibrium solution of the 1-d heat equation, when one end of the rod is maintained at a higher temperature than the other. There's a linear drop off of temperature.

With a linear dropoff, less steel would melt than in Dave's calculation, which assumed the heat is confined to the surface.

Please take another stab at this, Dave, but look beyond (i.e., at a later time) heat from the nano-thermite source magically not penetrating the steel column at a depth equal to that obtained by melting an outer layer. Also, consider what the temperature distribution would be like before complete thermal equilibrium is attained.

Doesn't Dave's calculation provide an upper bound for the effects before thermal equilibrium?

Yes, you need a computer to get an exact solution. Nevertheless, you should be able to make reasonable qualitative guesses.

A computer can tell you the consequences of your model, but it's unlikely to improve your model all by itself.

Will

 

[Dave Rogers]

Doesn't Dave's calculation provide an upper bound for the effects before thermal equilibrium?

Yes, it does. I've calculated the maximum amount of steel that could be melted, and it's negligible.

OK, now that I've got over the irritation at metamars whingeing that I haven't tried hard enough to prove his idiotic theories, let's try a linear temperature gradient. I know how much heat is present, so I can work out how far the gradient extends into the steel. In fact, I can scale it from the overall 105K temperature rise at equilibrium. Now let's see; assume the steel is at 1350 at the surface, the temperature decays linearly with depth, and the total heat content is the same as for a 105 degree rise over a 76mm flange. Average temperature of the heated region is 675 degrees, so the total heated thickness is a little under 12mm.

OK, metamars, there's your third case. The temperature of the column varies, in this approximation, linearly from 1350 degrees at the surface to room temperature 12mm below the surface. Only about 15% of the material is affected in any way. I'd read off the strength vs. temperature curve for steel and work out the total reduction in strength of the column, but I can't be bothered; the strength goes monotonically to zero at 1350 degrees and it's at about 50% somewhere around 600 degrees, so a reasonable guess would be that the column strength is reduced by about 10%. Global collapse, once again, does not ensue.

ETA: I've assumed that no steel melts. If any steel does melt, that reduces the energy available to heat the rest.

Bottom line: however you distribute it, there isn't enough energy here to do anything significant. If you want any more analysis, do it yourself.

Dave

PS. I see I mixed up kelvin and centigrade in my first calculation, so in effect I was assuming a melting point of only 1075ºC for the steel, and hence overestimated how much would melt. It's even less than that when you do the sums right. Again, I don't think correcting it would be a productive use of my time.

 

[Swing Dangler]

Wrong as usual.

http://en.wikipedia.org/wiki/Nano-thermite

Why do Govt. Truthers make so many mistakes or why do they lie?

James B-Hours after the fact? The troofers claim there were tons of molton metal weeks after the fact. They have yet to explain what version of thermite causes that.

Truthers don't claim that, eyewitnesses stated that.
Can you explain what type of jet fuel causes that? Nahh didn't think so. I've been gone from this site for so long but the stench of crap is still here. Why am I not surprised??

Surely James you can point to other office building fires that created molten steel, can't you?