(: Metal J Tube.

: Greetings. I am currently having a friend weld a 8" & a 6" J-tube for putting inside two different barrels configurations in place of the brick one. I have done one brick one before. I plan for the J-Tube to have 4 legs & be wrapped in a metal mesh with a perlite & fire clay mixture, then just going through a short earthen seat for one & the 2nd one to be part of a water heating system before if vents out.  I have the Rocket Mass Heater Builders Guide for the measurements of the J-Tube. I am using thick square stock steel for the J-Tube.
Has anyone here done a Metal J-Tube & have thoughts on this??
: BEST!
: Leanne-R: Phillips.

I think your rocket won't last very long. :(
Have a look at this thread where metal in the burn tube is discussed. If the metal isn't insulated (like some rocket stoves) it is likely to last longer I guess, but then won't be so efficient.