Steel alloy choice for wood fire service?
Steel alloy choice for wood fire service?
(OP)
Hi,
I'm building a maple syrup evaporator and need load bearing metal bar stock that will withstand thermals with direct exposure to wood fire (Google tells me this is around 600degC, but not sure the accuracy of that). I tried mild steel bar stock that was fine under ambient temperatures but deformed severely at temperature. What would be an affordable choice of metal for this application? Would 316 stainless be okay?
Thanks
I'm building a maple syrup evaporator and need load bearing metal bar stock that will withstand thermals with direct exposure to wood fire (Google tells me this is around 600degC, but not sure the accuracy of that). I tried mild steel bar stock that was fine under ambient temperatures but deformed severely at temperature. What would be an affordable choice of metal for this application? Would 316 stainless be okay?
Thanks





RE: Steel alloy choice for wood fire service?
RE: Steel alloy choice for wood fire service?
If you are getting a lot of scaling and metal loss then a stainless might make sense.
In reality this more of a mechanical issue.
Your main supports should be out of the direct heat. The rest need to have some 'give' to them.
I have melted Al in a wood fire, that is 660C.
= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube
RE: Steel alloy choice for wood fire service?
I see I can get carbon or galvanized steel bar grating for not that much money. But not sure if that will hold up better than what I used previously.
RE: Steel alloy choice for wood fire service?
It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.
RE: Steel alloy choice for wood fire service?
RE: Steel alloy choice for wood fire service?
Why does the support need to be in the fire?
Can you support or hang it from the upper lip?
= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube
RE: Steel alloy choice for wood fire service?
As an interim solution I just piled a stack of bricks in the middle of the fire pit to make a midpoint support. This greatly reduced the amount of sag as I can actually support a good portion of the weight of the maple sap tub/pot on the bricks instead of the steel bars (which I re-checked and found to only be .25" in thick not 0.5" steel). Low tech solution.
The downside of this is that it's taking up a good bit of space in the firepit, where I could otherwise be stacking logs for maintaining my boil. And it impedes the airflow. So I may still look to getting steel bar grating to replace these somewhat flimsy bar stock & brick combination.
RE: Steel alloy choice for wood fire service?
The important thing for the grate is that the bars spanning need to be taller.
In order to keep the bars from twisting is is common to weld small rods across them at the top and bottom.
This still lets them flex a bit but adds stiffness.
Mild steel should be fine.
= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube
RE: Steel alloy choice for wood fire service?