Weakened, compromised steel is what made the towers fall

[Elite Engineer]

I was having discussion with my friend yesterday, and he says the jet fuel from the jet that crashed into the towers cannot melt steel...which I fully agreed with

 

him. However, I argued (and I'm no engineer by any means) that the impact of the plane, the weight, and heat combined made the towers collapse. A 168 ton plane, flying

 

at 400 mph, had to have severlely weakened the immediate area that the aircraft impacted. Also, the steel beams were not engineered to hold a 168 ton aircraft, along with the

 

high temperatures inside the tower. All these factors combined lead me to believe this is what caused the first or few floors to buckle causing the towers to fall in a floor-to-floor

 

chain

 

reaction.

 

- Your thoughts?

 

~EE

[Sensei]

What Boeing 767 aircraft is made of? Aluminium. 80-104 tons of Aluminium.

 

What happens if Al join with f.e. Fe₂O₃ at high enough temperature.. ?

http://en.wikipedia.org/wiki/Thermite

 

There will happen very rapid chain reaction:

 

In WTC debris there has been found Thermite and melted iron.

And conspiracy seekers argue it's proof that government collapsed towers.

While it could be created in right circumstances spontaneously.

 

At high temperature water instantaneously changes to vapor, then separates to gaseous Hydrogen and Oxygen.

And Oxygen can react with anything, especially metals, especially Iron to create Fe₂O₃ f.e.

That's why certain types of fire can't be extinguished by water.

Because there is risk of explosion of gaseous Hydrogen and Oxygen.

Steady continuous supply of Oxygen gas to any fire can easily excess melting point of every element.

 

Thermal decomposition of water

http://en.wikipedia.org/wiki/Water_splitting#Thermal_decomposition_of_water

Edited April 11, 2015 by Sensei

[imatfaal]

Quite apart from interesting points made by Sensei; what temperatures were you thinking of Elite Engineer? Steel at 1000 deg C will be orange - and you wouldn't want to be using orange hot steel to support anything. And how hot jet a1 can burn at in the sort of wind you get at 1000 feet up and just offshore; I really don't know. Tell me - how does your friend know? FYG the max burn temperature of jet a1 is within a couple of hundred of coal

[John Cuthber]

What Boeing 767 aircraft is made of? Aluminium. 80-104 tons of Aluminium.

 

What happens if Al join with f.e. Fe₂O₃ at high enough temperature.. ?

http://en.wikipedia.org/wiki/Thermite

 

There will happen very rapid chain reaction:

 

In WTC debris there has been found Thermite and melted iron.

And conspiracy seekers argue it's proof that government collapsed towers.

While it could be created in right circumstances spontaneously.

 

At high temperature water instantaneously changes to vapor, then separates to gaseous Hydrogen and Oxygen.

And Oxygen can react with anything, especially metals, especially Iron to create Fe₂O₃ f.e.

That's why certain types of fire can't be extinguished by water.

Because there is risk of explosion of gaseous Hydrogen and Oxygen.

Steady continuous supply of Oxygen gas to any fire can easily excess melting point of every element.

 

Thermal decomposition of water

http://en.wikipedia.org/wiki/Water_splitting#Thermal_decomposition_of_water

 

"What happens if Al join with f.e. Fe₂O₃ at high enough temperature"

Why even ask the question?

People don't reinforce concrete with Fe2O3 do they?

If the steel has already oxidised to Fe2O3 then it's lost practically all its strength.

 

re."At high temperature water instantaneously changes to vapor, then separates to gaseous Hydrogen and Oxygen."

Barely.

You need to get to about 3000C before half the molecules break up.

At that temperature the concrete and the steel will be liquid.

So, it can't actually be relevant.

 

"In WTC debris there has been found Thermite and melted iron."

Not really.

There's plenty of aluminium from the structural components of the plane. And there's no shortage of iron and it's oxides from the rebar and rust etc.

 

"And Oxygen can react with anything, especially metals, especially Iron to create Fe₂O₃ f.e.That's why certain types of fire can't be extinguished by water."

Not really.

You can't put out, for example, a magnesium fire with water because magnesium will cheerfully burn in steam.

That's all the sort of nonsense that the conspiracy theorists make up.

It never did make sense and it should be dead and buried by now.

[Sensei]

Why even ask the question?

People don't reinforce concrete with Fe2O3 do they?

Of course it was not present at building time in significant amount.

 

Oxidation of steel bars happened during building life time and then accident.

 

US government source with photos of WTC melted steel bars with analyze what elements are present in them (that was not there prior accident):

http://www.fema.gov/media-library-data/20130726-1512-20490-8452/403_apc.pdf

 

 

Not really.

You can't put out, for example, a magnesium fire with water because magnesium will cheerfully burn in steam.

Nobody said a word about Magnesium in this thread..

[John Cuthber]

Of course it was not present at building time in significant amount.

 

Oxidation of steel bars happened during building life time and then accident.

 

US government source with photos of WTC melted steel bars with analyze what elements are present in them (that was not there prior accident):

http://www.fema.gov/media-library-data/20130726-1512-20490-8452/403_apc.pdf

 

 

 

Nobody said a word about Magnesium in this thread..

If the steel in the reinforcing bars had turned to Fe2O3 the building would have fallen down without needing to be hit by a plane.

So, in the real world, there just isn't much Fe2O3 to react with any Aluminium.

Nobody specifically mentioned magnesium but someone mentioned "certain types of fire can't be extinguished by water" and magnesium fires are a fairly well known example of that. I used magnesium as a specific example of the real reason why you can't put those fires out with water.

The web page you have cited doesn't say anything about thermite or aluminium. The element that is present in the debris that is not present in the original steel is sulphur.

About an eight of the weight of gypsum (used in plasterboard etc) is sulphur, so it's presence is perfectly predictable.

 

Why are you trying to argue?

Edited April 11, 2015 by John Cuthber

[Elite Engineer]

what temperatures were you thinking of Elite Engineer? Steel at 1000 deg C will be orange - and you wouldn't want to be using orange hot steel to support anything. And how hot jet a1 can burn at in the sort of wind you get at 1000 feet up and just offshore; I really don't know. Tell me - how does your friend know?

roughly 700-800 degrees C. Not exactly at 1000 C, but enough to begin the compromising of the steel beams in the tower. You made a good point about the wind velocity at that particular height in the towers, close to an off-shore location. However, I think its more than factoring in the wind speed at that height. It's factoring in the wind turbulence as it flows through the mangled tower structure. If you've ever had a fire in a chimenea you'd know that the design allows incoming wind to form a vortex inside the oven, resulting in increased air and higher temperautres. So the air flow in the tower would also be a major factor that could have increased the flame temperatures as well..maybe as high as 900-1000 C. BTW, my friend is just a guy who reads conspiracy forums, so no real competition here

[studiot]

Was that report linked by Sensei the best the US government could do?

 

I really can't see that it showed enough to conclude much of anything.

 

It is, however, well enough known that thick timber will hold its strength longer than equivalent structural steel in a fire, for UK building codes to require fire protection to supporting structural steel members.

Roof members are largely unprotected or lightly protected.

 

But that report tested such a tiny amount of steel for which it can't even identify the source that the conclusions are IMHO largely meaningless.

 

I have investigated steel motorway bridge beams following intense fires from road fuel tankers and did a more thorough job than that.

Edited April 12, 2015 by studiot

[Enthalpy]

Ordinary steel looses much of its strength around 500°C. If a fire has enough time to bring steel to 800°C, collapse. To compare with, steel is forged around 1200°C, still far from the melting point.

Edited April 14, 2015 by Enthalpy