SS Material for Batch Box Burn Chamber n Manifold Stack

Hello,

Am new to the forum, I have a few questions on my RMH design and materials I want to use, I have some 6" x 6" x 1/2" wall SS square tubing, I would like to know why this wouldn't work for the "Main" burn tubes for the Rocket portion of the stove including the upright exhaust into the Manifold, which will be a SS tank as well ?

Rocky,

Even regular austenic stainless steel of 304 family (321, 347 and even 310) will eventually fail (please read about sigma phase) but because people usually do not build from stainless (especially 6x6x0.5 which would be quite expensive nowadays) and because of that nobody really knows how long it will last. It may actually last longer that anybody thinks or longer than your desired lifespan of the heater. It would be great if you built it and report now and in a few years.

Thanks Cris,

I should be using some larger tubing for the riser, which I do have, but what about the insulation of the riser, is it necessary with this material or will it extend the life if I do insulate it ?

If you insulate it will shorten its life, because heat will not be able to be expelled by the steel. That's why heaters are not build from steel but from refractory ceramics and steel is used on the OUTSIDE to reinforce it and also to block the gas exchange in both directions (toxic gases while burning and incoming cold room air when cooling down). Also the firebox tube will become red hot and it also complicates things and helps to start a good fire of the building.