Fireproof paint for steel

Paint that protects 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 environmental corrosiveness class. 

Required fire resistance class

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

Massiveness of the steel section

Massiveness is an index defining the ratio of a section's perimeter to its cross-sectional area. Only the perimeter exposed to fire should be considered. For example, a beam supporting a reinforced concrete ceiling will only be exposed to fire on three sides. This value is specific to each cross-section, so when pricing a fireproofing system, the client must provide a steel structure specification. Large sections will have a lower massiveness index than small sections. For example, for HEB300, this index is 116 1⁄m, and for IPE100, it is as much as 387 1⁄m. The higher the massiveness index, the thicker the fireproof coating must be applied.

Design critical temperature

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

Environmental corrosion classes

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

Learn how to choose a fire protection system for steel.