Structural steel can be fire protected by a variety of methods, the most commonly used Passive fire protection tends to fall into one of the following three categories:
The material is inexpensive and was known to withstand even extremely high temperatures.
Lightweight cementitious fireproofing retains the benefit of being based on inexpensive raw materials and without the problems associated with extreme weight. As its name suggests, the material is significantly lighter than dense concrete and so doesn’t require the over-specification of structural steel. These products also share their predecessor’s tendency to crack.
Perhaps the biggest liability with a cementitious coating, though, is the inevitable creation of space between the coating and the substrate. This space has a tendency to collect moisture, which in turn fosters corrosion of the substrate. In the long run, this unfortunate flaw can actually cause a lightweight cementitious coating to work against the integrity of the asset it was meant to protect.
Intumescent coatings work by charring and expanding in the presence of extreme heat. The increase in volume and subsequent decrease in density slows the heating of the substrate, increasing the time before the steel itself begins to melt. Intumescent typically swell to 25 times their original thickness when engulfed in flames. This expansion allows them to provide a barrier between the flames and the steel that is exponentially larger than a coating that does not swell.
Adding thickness to an intumescent coating application increases the amount of swelling that will occur in the case of a fire incident.
When intumescent coatings come in single-component and multi component formulas, they are much simpler to apply than dense concrete and lightweight cementitious coatings and are therefore accompanied by far lower labor costs. But the material cost is high.
Additionally, since they are applied directly to steel, no gap is created in which moisture can sit and incite corrosion. Intumescent coatings fight corrosion in much the same way as traditional protective coatings, the difference being their ability to swell and the much greater thicknesses at which they are initially applied. With all of the benefits of intumescent coatings combined, it’s our recommended method of fireproofing steel.
Durability – these coating systems are typically durable and do not readily flake off when struck.
Versatility – Intumescents can be easily applied on- and off-site to a variety of surfaces.
Aesthetics – Good Aesthetics as compared to Cementitious.
Application and maintenance – Intumescent coating systems are relatively easy to apply and maintain.
Anticorrosion protection - extending their life significantly. In fact, intumescent coatings fight corrosion in much the same way as corrosion resistant coatings.