An Experimental Study on the Thermal Characteristics of Firestop Systems Depending on Physical Properties of Metallic Pipe Materials

We quantitatively analyzed the effects of physical properties of metallic pipe materials on the thermal performance of firestop systems. Fire-resistance tests under realistic fire conditions were conducted for 120 min using five types of metallic pipes—carbon steel, stainless steel, cast iron, copper, and aluminum—under identical firestop material conditions. The temperature distribution at key locations within the slab and average rate of temperature increase over specific time intervals were compared. Materials with higher thermal conductivity and lower wall thickness exhibited faster thermal response characteristics. High-temperature behavior was most pronounced at the pipe surface, where copper and aluminum pipes reached temperatures approximately equal to 200 °C and 190 °C, respectively. During the initial 30 min, the average rates of temperature increase were the highest for aluminum (2.9 °C/min), followed by copper (2.2 °C/min), although the rate of heat transfer gradually decreased subsequently. A correlation analysis between the composite index of thermal conductivity and cross-sectional area, revealed a strong correlation at the pipe’s surface, with a coefficient of determination greater than 0.85. The thermal properties and cross-sectional characteristics of metallic pipes can directly affect the thermal behaviors of firestop systems. The results may serve as a basis for material-informed structural design and performance evaluation criteria.