Fire resistant steel?

Question

Hi, does anyone know where i can find more about this topic ? fire resistant steels for structural applications. thanks

Answer 1

Steel is naturally "fire-resistant" in that it is not combustible (unlike wood).

When heated to extraordinary temperatures (usually above 500 or so Fahrenheit), it starts to loose stiffness and strength. This is why steel is typically enclosed - to prevent it from heating, not to prevent it from catching fire (like a wood structural element would).

What you are probably asking about is intumescent paint, this is a paint that is applied as a pretty thin, normal-looking coat of paint, but when it gets particularly hot, 'explodes' (expands) into a thick layer around the steel, which then acts as insulation (which is pretty commonly called fire-proofing but is more accurately insulation, it keeps the steel from heating up by insulating it). As a point of reference, the hourly rating given by UL rated assemblies are terminated if the steel reaches a certain temperature, so the intumescent paint keeps the steel from reaching that temperature as quickly, thus providing a fire-rating.

Alternates to intumescent paints (because they are quite expensive in the US and more popular in Europe) are gypsum wall board enclosures, or encasing in concrete, or other spray on foam 'fireproofing.' (I believe vermiculite was used in the past, and while it isn't quite the same as asbestos, there are some issues with it)

There was an article in Modern Steel Construction (via aisc.org) on fire protection that might answer more of your questions and substantiate what I've already written here.

Here's the article information:

Structural Fire Protection: Common Questions Answered, Alfawakhiri, Hewitt, Solomon, Modern Steel Construction, December 2002 (available free at the AISC.org website under Modern Steel Construction, Back Issues)
more or less direct link - http://www.modernsteel.com/Uploads/Issues/December_2002/2002_12_qa.pdf

google search for intumescent paint:
http://www.google.com/search?hl=en&rls=SUNA%2CSUNA%3A2006-01%2CSUNA%3Aen&q=intumescent+paint

Answer 2

In the fire protection world, we do not consider steel fire resistant. Of course it doesn't burn under ordinary conditions, but it lose strength as it is heated. As has been mentioned, there are coatings which insulate steel to enable it to withstand high ambient temperatures for a long time. Construction using this method is called fire resistive construction.

Answer 3

Gavin, the danger posed by steel columns and girders during a fire in a building, is not the danger of the steel melting but of the steel expanding and snapping the bolts that hold all of the steel together. Very high temperatures can be achieved in a building fire because the up-draft caused by the rising hot air, delivers a massive amount of oxygen to the burning carpet, paper and furniture. When a steel frame office tower burns, the heat expands the steel and snaps the bolts. This causes the building to "fall-down" and not necessarily, "burn-down". I am too lazy to look-up the melting point of steel but it is not very high. That is one reason for the columns and girders in steel framed buildings, to be covered in asbestos (which is a fatally toxic material) or magnesium di-oxide.

Answer 4

There is a chemical that is used presently that is sprayed onto steel beams called Monocoat. Its a form of insulation that gives steel protection for up to 2 hours I think. Hope that helps!

Answer 5

Steel is extremely flammable in a fire and needs to have a fire retardant coating to meet most building codes.