How Do the Intumescent Coatings Work?
The Basic Principle of Intumescent Coating
Fire protection of structural steel is attained by painting the steel structures with a special protective paint – an intumescent coating. The intumescent coating expands at high temperatures and forms a protective, insulating layer on the surface of the steel. Therefore, in a fire, the steel structure will be protected for a given period of time while the people are safely evacuated and the fire fighters can extinguish the blaze.
What is a Critical Temperature?
The high temperatures reached during a building fire trigger significant changes in the structural properties of steel. Already at 300 °C, the strength of the steel begins to decrease. At 400 °C, the structural strength of the steel has been reduced by 60% of its original capability. To put these temperatures in to a context a typical building fire exceeds 1000°C.
Should the steel structure reach it critical failure temperature (typically 550-650°C), the steel would no longer be able to support the load of the building. The steels would then distort and collapse from the weight of the building. The critical temperature is the temperature at which the steel can no longer fully carry a designed load, therefore its load bearing capabilities can no longer be relied upon.
Nullifire Intumescent Coatings extend the time when, exposed to fire conditions, the steel reaches the critical temperature. This extension of time is specified typically by the usage of the building, however maybe up to 120 minutes.