62953 2025 eng 1 12 153 article Elsevier Ltd. 1 -- -- -- Intumescent coatings are commonly used in civil engineering to increase the fire resistance of steel structures. Exposed to fire, the intumescent coating reacts and forms a thermal protective char around the steel member. Thus, the heating of the steel is significantly slowed down and the fire resistance can be improved. Information regarding the scope of application and the durability of intumescent coatings are given in national approvals or European Technical Assessment documents. Due to the environmental conditions, intumescent coatings are subjected to ageing effects, which can reduce the durability and their thermal protection performance. To predict the durability for several years, during the approval procedure the behaviour of intumescent coatings is predominantly extrapolated based on accelerated artificial ageing. The established German and European assessment procedures to test and assess durability assume a working life of at least 10 years. Additional evidence may be required for longer periods. However, at present there is no method of verifying the thermal performance of existing structural members on site. For this reason, BAM is conducting the research project "INSIST" [1] to develop a minimally invasive in situ test method to determine the fire resistance of existing steel structures with applied intumescent coating. The investigation includes the development of a mobile prototype furnace. The paper describes the test setup, the developed prototype furnace, and the results of the performed test programme on uncoated and coated steel specimens. Based on this, recommendations for the test procedure are given. 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Published by Elsevier Ltd.","name":"copyright","label":"Copyright"}],"article-number":"104380"}} journal-article publish 16.04.2025 Creative Commons - CC BY - Namensnennung 4.0 International Richard Fürst Dustin Häßler Ludwig Stelzner Sascha Hothan eng uncontrolled In situ testing eng uncontrolled Fire resistance eng uncontrolled Intumescent coating eng uncontrolled Steel eng uncontrolled Thermal protection eng uncontrolled Durability Ingenieurbau 7 Bauwerkssicherheit 7.3 Brandingenieurwesen Infrastruktur Fire Science Verlagsliteratur Datei für die Öffentlichkeit verfügbar ("Open Access") Wissenschaftliche Artikel der BAM Bundesanstalt für Materialforschung und -prüfung (BAM) https://opus4.kobv.de/opus4-bam/files/62953/Insitu_testing_of_intumescent_coating.pdf