Fireproof paint for steel

Paint protecting steel against fire.

The selection of a fire protection system for a steel structure is a complex process and depends on several factors: the required fire resistance class, the massiveness of the steel cross-section, the designed critical temperature, and the corrosiveness class of the environment. 

Required fire resistance class

The resistance class is indicated by the symbol: R15, R30, R60, even up to R120. The number indicates the time in minutes, i.e. how long the structure will be protected against fire.

Massivity of the steel cross-section

Massivity is an indicator determining the ratio of the section's circumference to its cross-sectional area. Only the perimeter exposed to fire should be considered. For example, a beam supporting a reinforced concrete ceiling will be exposed to fire on only three sides. This value is characteristic for each cross-section, therefore, when pricing the fire protection system, it is necessary for the customer to provide a list of the steel structure. Large sections will have a lower section massiveness index than small sections. For example, for HEB300 this indicator is 116 1⁄m, and for IPE100 as much as 387 1⁄m. The higher the solidity index, the thicker the coating of fire retardant paint must be applied.

Designed critical temperature

For the same cross-sectional mass, the thickness of the fireproof coating will change depending on the designed critical temperature. The higher the critical temperature, the lower the coating thickness.

Environmental corrosivity classes

Depending on whether our structure will operate in a C2 or C4 environment, an appropriate primer and topcoat system should be selected. The full fire protection system is applied in three stages: anti-corrosion primer, fire retardant paint, topcoat.

Based on the factors mentioned above, we finally determine the thickness of the fire-retardant coating by reading it from the appropriate table in the technical approval of the fire-retardant paint.

Find out how to choose a fire protection system for steel.