Evaluating the impact of testing conditions on intumescent coatings' fire performance: A comparison of laboratory-scale and industrial-scale experiments

Steel is extensively utilized in construction but loses mechanical strength at elevated temperatures, posing a risk of structural failure during fires. Fire protection measures, such as intumescent coatings, are essential to ensure safe evacuation times. Regulatory standards necessitate fire testing of materials using defined fire curves in industrial furnaces, which are energy-intensive, costly, and time-consuming. To mitigate these issues, laboratory-scale (lab-scale) methods are employed to reduce costs and enhance efficiency. However, lab-scale tests, typically conducted on flat plate samples, may not accurately represent conditions in industrial furnaces. Therefore, it is imperative to systematically assess the discrepancies in intumescent coating performance between lab-scale and industrial-scale environments. This study aims to examine the influence of various testing conditions on the fire performance of intumescent coatings by comparing results from lab-scale and industrial-scale tests with two different fire scenarios, namely the hydrocarbon and cellulosic fire curves. It is shown that lab-scale flat plates closely resemble the exterior of H-columns and hollow structures. Additionally, a good agreement in expansion ratios between the exterior of H-column and hollow structures was achieved in the lab-scale tests. Replicating the thermal conditions and higher coating expansions inside the H-column web is however more challenging with flat plate lab-scale experiments.