Why are intumescent fire resistant coatings required for the protection of steel in building construction?

The mechanical properties of steel are very stable at temperatures less than 250℃, however strength will decrease as temperature increases above 300℃.  This is especially true when the temperature is in the range between 450 - 650℃ where the steel strength decreases rapidly, leading to the collapse of the building.  Therefore the fire resistant protection of an intumescent coating is necessary in order to attain fire protection in accordance with building codes throughout the World.

Furthermore intumescent coating is a desirable approach because it is a thin, white coating that has an attractive appearance.

Example Case:

The World Trade Center of Manhattan catastrophically collapsed during the 9/11 attack. The steel support beams of the building failed due to the intense heat and high temperature of the burning aircraft fuel. The building was designed before fire resistant coating protection was required. Potentially lives could have been saved if the building’s collapse would have been delayed via coating the steel beams with a fire resistant intumescent coating.

The theory of fireproofing:

Insulation effect，the heat transfer is stopped by intumescent carbon layer

Heat absorption because of the intumescent process, it will absorb lots of heat during the process of softening , fusion, evaporation and intumescence of the coating and resolving of the carbon layer.

Oxygen isolation, the intumescent carbon layer have the function of covering.

Dilute the oxygen content and release the non-inflammable gas.

Flame retardant solutions for intumescent coating:

Acid source: JLS-APP series

Gas source: JLS-MELAMINE

Carbon source: JLS-PENTA

Classic three sources intumescent system, suitable for water based/solvent based extra-thin/thin intumescent coating.

Epoxy based intumescent coating: JLS-APP104MF

Flame resistant standards: EN, DIN, BS, ASTM, GB.