I found the following article about a petroleum storage burning with even a movie. Ken Revart writes:

 It appears to me that the the thermal insulation on the spheres begins to char at the equator from radiant heat and then ignites after subsequent explosions. I understand that this facility installed PUR/PIR foam insulation for cold process. I have to wonder how the pipe insulation stood up to the fire. Did the PUR/PIR melt away and contribute to the cascading affect of the explosions.

What are your thoughts or experiences of fire protection from mechanical insulation in these scenarios? (I skipped the last sentence to respect a legal settlement)

With GLAPOR cellular glass, this catastrophe would never happen because cellular glass is non-combustible. It is produced from 99.9% glass without using any binder. In fact, reinforced with a ceramic mesh on the opposite side of the fire, it behaves as a very good fire resistance.