Service-paint

Fire protective (or intumiscent) painting of steel

How does an intumescent paint work?

In the case of an intumescent paint, when subjected to temperatures exceeding 120°C the paint will intumesce (swell up to 50 times the thickness of the paint) and form a carbon layer (Char) which, in the case of intumescent steel paint, thermally insulates the steel substrate and maintain a temperature below 550°C or 620°C for a given period of time.

Intumiscent paint is designed to increase the time period that a structural load bearing steel within a building will last during a fire. The paint works by intumescing or expanding to create an insulation barrier on the steel and increasing the time period to 240 minutes. During a fire it can just take a few minutes for the temperature of unprotected steel to reach 550 C, at this point steelwork loses its structural load bearing capacity and can buckle causing a building to potentially collapse.

Intumescent paints are the most common form of fire protection to steel. This is because of how widely available the products are and how cheap they are.

Why is it needed?

In a fire it is critical that the structural steel frame of the building is protected correctly so that the steels do not reach their critical failure temperature which is between 550°C and 620°C. Below these critical temperatures the structural steel exists in a state of Elasticity which allows the steel to bend/deflect and return to its original state once the force has been removed. If the temperature increases above the critical temperatures the structural steel under load goes into a state called Plastic which means the steel will buckle and bend potentially causing the building to collapse.

What forms does it have?

Intumescent paints and coatings are available in Water and Solvent based forms with fire ratings of 240 minute utilising thin film intumescent technology and intumescent technology.