@Dave1000car It is the burner on a South African made 2pint primus. The pipe is standard copper plumbing waste pipe with O.D. 40mm. Brass tube can be purchased in various diameters on Ebay. It will be coming from China so delivery may be slow but they are still shipping around the world.
Good man . Looks excellent and you get the good feeling of not buying your way out of a problem. Slàinte