Experimental Analysis of the Temperature Rise Characteristics in Nonmetallic Pipe Firestop Systems

Elucidating the high-temperature characteristics of nonmetallic pipe firestop systems is challenging because they undergo softening, deformation, melting, or pyrolysis at high temperatures, and experimental data examining the high-temperature behavior of nonmetallic pipe materials, including the effects of pipe thickness and diameter conditions for materials within the same polyvinyl chloride (PVC) series, are limited. This study addresses these gaps by investigating the effects of the nonmetallic pipe material and dimensional conditions of the PVC pipe on the temperature response of firestop systems. PVC, fire-safety-enhanced PVC [PVC(F)], polyethylene (PE), and fiber-reinforced polymer (FRP) pipes, together with PVC(VG1/VG2) pipes ranging from 50A to 150A, were tested under an ISO 834-1 standard fire exposure test. Temperature responses were compared at the pipe outer surface and adjacent opening finish above the annular gap to distinguish pipe and firestop behavior. At 120 min, pipe-surface temperatures were 135.8, 152.2, 97.9, and 239.9 °C for PVC, PVC(F), PE, and FRP, respectively. PE melted and lost geometry, FRP largely retained its geometry, and PVC and PVC(F) showed intermediate responses with softening, partial loss, and residue formation. For PVC(VG1/VG2), temperatures generally increased with diameter, with greater VG1–VG2 differences at larger diameters.