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The steel was definitely very hot you can see black patches,
Remember tower 2 collapsed in about 40+ minutes after impact. So the fireproofing had to be removed by NIST no matter what!
The steel was definitely very hot you can see black patches,
Tempering (metallurgy)
en.m.wikipedia.org...(metallurgy)
If steel has been freshly ground, sanded, or polished, it will form an oxide layer on its surface when heated. As the temperature of the steel is increased, the thickness of the iron oxide will also increase. Although iron oxide is not normally transparent, such thin layers do allow light to pass through, reflecting off both the upper and lower surfaces of the layer. This causes a phenomenon called thin-film interference, which produces colors on the surface. As the thickness of this layer increases with temperature, it causes the colors to change from a very light yellow, to brown, then purple, then blue. These colors appear at very precise temperatures, and provide the blacksmith with a very accurate gauge for measuring the temperature. The various colors, their corresponding temperatures, and some of their uses are:
Faint-yellow – 176 °C (349 °F) – engravers, razors, scrapers
Light-straw – 205 °C (401 °F) – rock drills, reamers, metal-cutting saws
Dark-straw – 226 °C (439 °F) – scribers, planer blades
Brown – 260 °C (500 °F) – taps, dies, drill bits, hammers, cold chisels
Purple – 282 °C (540 °F) – surgical tools, punches, stone carving tools
Dark blue – 310 °C (590 °F) – screwdrivers, wrenches
Light blue – 337 °C (639 °F) – springs, wood-cutting saws
Grey-blue – 371 °C (700 °F) and higher – structural steel
Beyond the grey-blue color, the iron oxide loses its transparency, and the temperature can no longer be judged in this way.
Hot black oxide Edit
Hot baths of sodium hydroxide, nitrates, and nitrites[3] at 141 °C (286 °F)[4] are used to convert the surface of the material into magnetite (Fe3O4). Water must be periodically added to the bath, with proper controls to prevent a steam explosion.
Hot blackening involves dipping the part into various tanks. The workpiece is usually "dipped" by automated part carriers for transportation between tanks. These tanks contain, in order, alkaline cleaner, water, caustic soda at 140.5 °C (284.9 °F) (the blackening compound), and finally the sealant, which is usually oil. The caustic soda bonds chemically to the surface of the metal, creating a porous base layer on the part. Oil is then applied to the heated part, which seals it by "sinking" into the applied porous layer. It is the oil that prevents the corrosion of the workpiece. There are many advantages of blackening, mainly:
Blackening can be done in large batches (ideal for small parts).
There is no significant dimensional impact (the blacking process creates a layer about a micrometre thick).
It is far cheaper than similar corrosion protection systems, such as paint and electroplating.
The oldest and most widely used specification for hot black oxide is MIL-DTL-13924, which covers four classes of processes for different substrates. Alternate specifications include AMS 2485, ASTM D769, and ISO 11408.
This is the process used to blacken wire ropes for theatrical applications and flying effects.
Mid-temperature black oxide Edit
Like hot black oxide, mid-temperature black oxide converts the surface of the metal to magnetite (Fe3O4). However, mid-temperature black oxide blackens at a temperature of 220–245 °F (104–118 °C), significantly less than hot black oxide. This is advantageous because it is below the solution's boiling point, meaning there are no caustic fumes produced.[5]
Since mid-temperature black oxide is most comparable to hot black oxide, it also can meet the military specification MIL-DTL-13924, as well as AMS 2485.[6]
Cold black oxide Edit
Cold black oxide is applied at room temperature. It is not an oxide conversion coating, but rather a deposited copper selenium compound. Cold black oxide offers higher productivity and is convenient for in-house blackening. This coating produces a similar color to the one the oxide conversion does, but tends to rub off easily and offers less abrasion resistance. The application of oil, wax, or lacquer brings the corrosion resistance up to par with the hot and mid-temperature. One application for cold black oxide process would be in tooling and architectural finishing on steel (patina for steel).[7] It is also known as cold bluing.
en.m.wikipedia.org...
originally posted by: Hulseyreport
There practically no evidence the fireproofing was removed on upper floors
originally posted by: waypastvne
originally posted by: Hulseyreport
There practically no evidence the fireproofing was removed on upper floors
No evidence except for the 1/2" of fireproofing dust lying on the ground after the planes hit.
originally posted by: Hulseyreport
Fireproofing insulation.
originally posted by: waypastvne
originally posted by: turbonium1
All that matters is - a structure cannot collapse through itself, and never will. It is impossible. Physics proves it is impossible. It is not possible to replicate such a collapse, in any way.
There are a lot of papers written about something you say doesn't exist.
www.google.com...
Your opinion doesn't matter, never will, because you are wrong.
originally posted by: turbonium1
You can point to stacks of papers, and claim 'that shows you are wrong', all you want.
Failure of Welded Floor Truss Connections from the Exterior Wall during Collapse of the World Trade Center Towers
app.aws.org...
Summary
Analysis of the connections supporting the composite floor system of the WTC towers showed that at and below the im- pact floors, the greater majority (above 90%) of the floor truss connections were either bent downward or completely re- moved from the exterior column. This was probably related to the overloading of the floors below the impact region after col- lapse initiation. Depending upon weld joint geometry, detachment of the main load-bearing seats was a result of either fracture in the heat affected zone of the base material (standoff plate detached from spandrel) or through the weld metal (seat angle detached from standoff plate). Failure in both cases was assumed to be a result of a shear mechanism as a result of overloading from floors above impacting those below. There did not appear to be a significant change in distribution of failure modes of the floor truss connections when comparing those connections inside vs. outside of the impact region or those ex- posed to pre-collapse fires and those that were not.
originally posted by: waypastvne
originally posted by: Hulseyreport
Fireproofing insulation.
There is no fireproofing on the steel in that photo.
originally posted by: neutronflux
a reply to: Hulseyreport
You
The steel was definitely very hot you can see black patches,
False argument. Fire running oxygen lean makes soot that stains steel and material.
Notice the pictured below? Cut by torch. The steel is not black on the cut. Is a dull metallic grey.
originally posted by: waypastvne
originally posted by: Hulseyreport
There practically no evidence the fireproofing was removed on upper floors
No evidence except for the 1/2" of fireproofing dust lying on the ground after the planes hit.
originally posted by: waypastvne
originally posted by: turbonium1
You can point to stacks of papers, and claim 'that shows you are wrong', all you want.
You can point at this photo and say that truss seat can not be broken, all you want. We know you are wrong. It has an ultimate strength, it is 94000 pounds. On 9/11 that limit was exceeded.
We have explained to you how the building collapsed.
Now, for a change, why don't you explain to us, why the building can't collapse, using physics.
Go get your eyes checked then? I can see the spray-on foam still there.
That's NIST claim.
You merely look at the construction to notice a floor truss failure crushing the hat truss very unlikely.
originally posted by: Hulseyreport
Go get your eyes checked then? I can see the spray-on foam still there.