Study of Industrial Grade Thermal Insulation as Passive Fire Protection up to 1200 °C

Abstract

It has recently been demonstrated that 50 mm thick industrial grade thermal insulation may serve as passive fire protection of jet fire exposed thick walled steel distillation columns. The present study investigates the performance of thermal insulation in conjunction to 3 mm, 6 mm, 12 mm and 16 mm steel walls, i.e., where the wall represents less heat sink, when exposed to 350 kW/m2 heat load. Regardless of the tested steel plate thicknesses, about 10 min passed before a nearly linear steel temperature increase versus time was observed. Thereafter, the thinnest plates systematically showed a faster temperature increase than the thickest plates confirming the wall heat sink effect. To study thermal insulation sintering, 50 mm thermal insulation cubes were heat treated (30 min holding time) at temperatures up to 1100 °C. No clear sign of melting was observed, but sintering resulted in 25% shrinkage at 1100 °C. Thermogravimetric analysis to 1300 °C revealed mass loss peaks due to anti-dusting material at 250 °C and Bakelite binder at 460 °C. No significant mass change occurred above 1000 °C. Differential scanning calorimetry to 1300 °C revealed endothermic processes related to the anti-dusting material and Bakelite mass losses, as well as a conspicuous endothermic peak at 1220 °C. This peak is most likely due to melting. The endothermic processes involved when heating the thermal insulation may to a large part explain the 10 min delay in steel plate temperature increase during fire testing. Overall, the tested thermal insulation performed surprisingly well also for protecting the thin steel plates.

Study of Industrial Grade Thermal Insulation at Elevated Temperatures

“…Thus, the second peak was only observed in test specimens treated at 900 °C and above. As stated in [ 11 ], the first peak (exothermic reaction) may be explained by the combustion of the dust binder due to the ambient air atmosphere in the furnace. The second exothermic peak may be explained by the crystallisation of the amorphous silica (SiO 2 ) in the thermal insulation.…”

“…In the present study, industrial-grade pipe section mat (ProRox PSM 971, thickness 50 mm, Trondheim, Norway) delivered by Rockwool, Inc., was studied as a representative industrial thermal insulation, i.e., the same thermal insulation as in previous studies [ 10 , 11 ]. The detailed technical data and thermal conductivity of this thermal insulation up to 350 °C are presented in Appendix A , Table A1 and Table A2 .…”

“…Previous studies of 50 mm thick thermal insulation (ProRox PSM 971, 50 mm, Rockwool) protecting a 16 mm thick steel wall using small scale testing [ 10 , 11 ] rather than full-scale testing [ 12 ] demonstrated that the thermal insulation alone was sufficient to withstand 30 min of jet fire exposure. Even with only 3 mm thick steel walls, the testing showed sufficient fire protection for 20 min.…”

“…The sintering and melting of the insulation due to the heat exposure resulted in cracks/openings in the insulation mat, as shown in Figure 1 b,c. The previous oven testing up to 1100 °C [ 11 ] showed minimal shrinking (less than 25%) of the thermal insulation. Hence, a further examination of the thermal insulation, explaining the observations in the small-scale jet fire testing [ 10 , 11 ] and determining the breakdown temperature of the insulation are the motivations for the present study.…”

“…Sjöström et al [ 13 ] and Olsen et al [ 14 ], performed oven tests of a Rockwool insulation similar to that of Bjørge et al [ 11 ], i.e., recording the temperature in the centre of the insulation. In addition, thermogravimetric analysis (TGA)/differential scanning calorimetry (DSC) tests and transient plane source method (TPS) measurements were performed.…”