firetube means A tube conveying hot gas in a boiler. Lexicurio rates it Sui generis — a strength score of 91 out of 100.
Etymology
From fire + tube.
noun
- A tube conveying hot gas in a boiler.“In a conventional boiler, the hot gases from the firebox, after passing through the firetubes, arrive in the smokebox and then pass up the chimney to atmosphere.”