A survey of commercial intumescent coating performance – contribution to the fire resistance of structural steel according to EN 13381 and BS 476

The fire resistance of structural steel can be improved if it is coated with intumescent coating. Many intumescent coatings, tested according to standardized large-scale tests, are available on the market. In this work, data for 62 coatings, tested according to EN 13381-8 and/or BS 476-20/21, was compiled and analyzed. This was done to provide an overview of what fire-resistance performance can be expected from commercially available technologies and to identify trends in the data. The data shows that the fire resistance time tend to be 10-15% lower when testing according to EN compared to BS. A comparison of data for rectangular and circular hollow sections reveals no consistent difference in fire resistance performance, indicating that any differences are a consequence of the individual coating behavior. For a given design temperature, the fire resistance time of I/H-sections is almost always higher compared to that of a corresponding hollow section. The difference was shown to be more pronounced at high section factors and/or low dry-film thicknesses. For I/H-sections, 3-sided exposure has a performance similar to 4-sided exposure, whereas rectangular hollow sections tend to have a somewhat higher fire-resistance with 3-sided exposure. Possible explanations for the observed trends are discussed in this review.