Erica Wisner wrote:[
We've done galvanized heat risers before; they're not our top choice. Generally too thin, and once the galvanized burns off, the steel underneath will crisp like overcooked bacon (6-18 months). So this is a good area to use something more durable, or create your own insulative ceramic materials.
For metal pipe, what would the recommended 'something more durable' for a heat riser be?
I am working on a Rocket Mass Forge.
http://mike.creuzer.com/topic/builds/his/rmhf (or more specifically
http://mike.creuzer.com/2011/10/rocket-mass-forge.html ) This would start with the heat riser, as I need an open space under it for the forge fire. If I am going to do woodworking in the garage, I can lay in a quick brick burn tunnel for the day. The whole thing is 'disposable', getting tore apart in the spring. The heat riser just needs to hold together for 6 months. However, if I can get something that will last several years for not much more money than the galvanized, I'd like to go that route.
I am using the lid of the barrel with two 6" holes, and setting the barrel upside down over the top of it. As there isn't any support at the front due to the forge fire being located here, I can't use a masonry heat riser, the weight would tip the hole thing over. So, it's 2 pieces of duct pipe of some sort with ash & perlite insulation. I was going to get more 6" galvanized as it's in a drafty garage, and the burning off of the duct happens inside the barrel, so the poisons gets vented outside anyhow. But, I am in a tightly packed residential area, and am not keen on poisoning anybody.
I had built a paint can pocket rocket using 3 inch double gas water heater pipe and 'crisped' the inner pipe within a half dozen burns. Crisped it 1/3 the way up the pipe! Photo can be found on
http://mike.creuzer.com/2011/05/twitter-updates-for-2011-05-02.html
Is the 24 gauge black pipe good enough? Does the stainless last any longer? I'd think the black pipe would be a good compromise between safety, durability, and cost.