PIN FR coatings for fire protection of steel
Intumescent coatings using tannic acid, APP and epoxy showed torch heat resistance up to 20 minutes. The intumescent PIN FR coating was made using tannic acid (derived from gall nuts) @ 43% w/w plus the inorganic salt PIN FR ammonium polyphosphate @ 11% w/w in epoxy (EPON 828 epoxy 28% – Ancamide 503 amine hardener 19%). A coating of 1 mm was applied by brush to a 6.3 mm steel plate. This was subjected to a 130 kW/m2 methane torch. Detailed COMSOL-based heat transfer modelling closely matched experimental outcomes: the PIN FR coating reduced backside heat by 90%, keeping the steel below 250°C, that is well below the critical temperature for structural failure (550-600°C) after 20 minutes of exposure to the torch flame.
“Experimental and Numerical Approaches to Optimize Heat Blocking Efficiency in Intumescent Coatings”, T. Hafiz et al., NAFEMS EMAS vol. 2 issue 1, 2025, https://doi.org/10.59972/xny38fpw
