## 2 Experimental Plan and Method
### Experimental Method  
The fire-resistance tests were conducted to evaluate the performance of firestop systems used in pipe-penetration assemblies. The tests followed the standard procedure outlined in KS F ISO 10295-1:2021 for fire-resistance testing of penetration seals [20]. The applied heating condition conformed to the ISO 834 standard temperature-time curve [21], with furnace temperature controlled as a nonlinear function of time (Equation (1)). This theoretical curve is shown in Figure 2[21] compared with the experimentally measured furnace temperature curves for both metallic and non-metallic pipe tests. \[T=345\log_{10}(8t+1)+20 \tag{1}\] \begin{table}
\begin{tabular}{c c c c c} \hline \multirow{2}{*}{**Slab Structure**} & **Outer Diameter of** & **Pipe Wall** & **Outer Diameter of** & **Firestop-Material Size** \\  & **Metallic Pipe (mm)** & **Thickness (mm)** & **Sleeve (PP) (mm)** & **(Thickness \(\times\) Width \(\times\) Length, mm)** \\ \hline Autoclaved & 60.5 & 3.65 & 140 & 7.8 \(\times\) 40 \(\times\) 400 \\  & 89.1 & 4.05 & 165 & 7.8 \(\times\) 40 \(\times\) 480 \\ lightweight & 114.3 & 4.5 & 187 & 7.8 \(\times\) 40 \(\times\) 560 \\ concrete slab & 139.8 & 4.85 & 187 & 7.8 \(\times\) 40 \(\times\) 560 \\ \hline \end{tabular}
\end{table} 
Table 1: Experimental conditions for metallic pipes. Figure 1: Installation views of pipe-penetration specimens. where \(T\) is the temperature (in \({}^{\circ}\)C) and \(t\) is the time (in minutes). Experiments were conducted in a 4 m \(\times\) 3 m horizontal furnace, with metallic and nonmetallic pipe specimens installed and evaluated independently. The specimen configurations and thermocouple-attachment positions are shown in Figure 3. All specimens featured a single-penetration design comprising a sleeve-integrated firestop and a mounting frame, installed in a 150 mm-thick autoclaved lightweight concrete floor slab. The firestop material whose volume was adjusted in this study, refers to the intumescent sealant applied circumferentially at the interface between the pipe and the slab. This is indicated by the red-shaded zone labeled \"Firestop material\" in Figure 3 and is distinct from the insulation layers applied above the slab for metallic-pipe specimens. For penetrants, carbon-steel pipes conforming to KS D 3562 [22] were used for metallic specimens, and unplasticized polyvinyl chloride pipes conforming to KS M 3404 [23] were used for nonmetallic specimens. The exposed length of each pipe below the heated surface was fixed at 1000 mm. The insulation materials used for the metallic-pipe specimens included both inorganic (ceramic fiber blankets) and organic (cross-linked polyethylene (PE) foam) types. The ceramic fiber blanket, a high-temperature insulation material, had a density of at least 96 kg/m\({}^{3}\) and a thermal conductivity of 0.090 W/(m\(\cdot\)K) at an average temperature of 300 \({}^{\circ}\)C. The PE-foam insulation had a thermal conductivity below 0.043 W/(m\(\cdot\)K). For metallic-pipe penetrations, the insulation was arranged as shown in Figure 3b. At the slab surface around the pipe, a 25 mm-thick, 300 mm-high ceramic fiber blanket was installed; above this, a 25 mm-thick, 300 mm-high PE insulation layer was applied; a 25 mm-thick, 100 mm-high PE layer was then applied; and finally, a 25 mm-thick, 400 mm-high PE layer was installed above the ceramic blanket. Thermocouple locations for measuring the unexposed surface were marked with black dots and attached to the specimens' rear side, on the exposed faces of the insulation and the pipes. For nonmetallic specimens, two thermocouples were installed on each of the floor, mounting frame, and pipe--a total of six. The three-layer insulation fully enclosed the floor surface for metallic specimens; therefore, no floor thermocouples were used; instead, two thermocouples were placed at the bottom, middle, and top sections of the insulation, and on the metallic-pipe surface.