Joe on Nostr: Category 3 is an insulated, multi layer pipe. the whole point is to prevent burning ...

Category 3 is an insulated, multi layer pipe. the whole point is to prevent burning materials in direct contact with the pipe, like roofs or walls. Generally you also want a 1" gap between the pipe and surrounding materials. Your pipe idea shoukd work fine, so long as the pipe does not come into contact with flammable materials.