What is the stable operating temperature of insulation cork?Updated a day ago

Insulation cork has a stable operating temperature of -180°C to +120°C (–292°F to 248°F). It can withstand short burst up to 140-150°C (284–302°F)

Keep in mind that cork is not fireproof. It is self-extinguishing meaning that it typically does not sustain combustion without an active flame. It will char and release CO2 smoke under flame. However, under very high temperatures (outside of the above range), these properties change and there can be thermal degradation and active flaming.