Combustible material?

Furnace & water heater flue pipe touching duct wrap. Is HVAC wrap considered a combustible material?


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What is it up against on the other side?..looks unplanned…homeownerish.

The insulation duct I installed last year had a flammability of 0 but hard to say what that is for sure or what’s under it. It looks too loose and baggy for insulation duct but could be.

On the left is a thermal expansion safety tank above the water heater.