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SS Fire grate question.

NooBBQNooBBQ Posts: 134
edited 5:31PM in EggHead Forum
Due to connections and profession, it would be fairly easy for me to have a fire grate made out of SS for little or no cost.

Given my current grate is cracked, I am contemplating doing just that.

Now some questions, obviously the SS would have to be a certain thickness just to work mechanically at the heat engaged. Also it would have to be acid resistant (so a higher grade SS) as somewhere in the process of fire and smoke, you will engage H2SO4 and H2SO3.

Now as far as warpage, would I be better of going as thin as possible (like the turbo grade) or go beefy 3/8 or so?



  • Photo EggPhoto Egg Posts: 7,906
    nm edit.
    Thank you,

    Galveston Texas
  • fishlessmanfishlessman Posts: 23,020
    i went with an inconel 625 series at .125 thick. ive added more holes since this pic was taken and it still looks new after several 12oo degree cooks. i melted thru a couple of cast grates. make it a little larger for more air flow, it helps with speed getting things up to temp


  • Grandpas GrubGrandpas Grub Posts: 14,226
    That sure is a nice looking grate.

  • BBQEdBBQEd Posts: 63

    Do you worry about Ni leaching into the cook from the Inconel? Beside the ungodly cost of Inc. I was afraid to use it in my Stump clone because of the high Ni content. I kicked around making the firebox from 1/4 622 but chose to use 304 SS in the end. I tried to find any information about Inconel being used in food preparation but couldn't. Also, I wouldn't have thought 10 Ga would have held up that well. We use a lot of Inconel 622 for coal fired power plant work and 625 in garbage burners and BOF's so we occasionally have decent sized drops laying around ;)

    I haven't run my clone at very high temps but for now the SS firebox and cook chamber appear to be holding up very well.
  • NooBBQNooBBQ Posts: 134
    So did you end up with 1/4" SS? (I would likely go with a higher grade than 304)

    Does it stay straight?

    Did you more or less copy the dimensions and holes from the original?

    Any heat treatment to destress it before use?

  • fishlessmanfishlessman Posts: 23,020
    the 625 is pretty stable stuff, i build heat sheilding where the temps are brought up past 3600 f. its an inert environment so its different than in a cooker but the inconel stands up well were the stainless parts i make become unstable, the stainless turns to mush loosing its tensile and the metal turns a dark green/grey with the stainless gassing off.
  • stikestike Posts: 15,597
    what will stainless do for you that thick cast iron won't? i mean, other than being affordable and easily obtainable for you (which is a pretty damn good reason!)

    it's not going to be much better structurally, will it?

    no matter your reason, i vote "sure". what's the harm?

    if you're interested, though, here's a little history as far as the forum goes:

    when someone here suggests making a raised grid of bolts and washers married to a spare grid, invariably someone will mention it needs to be made of stainless steel, and not galvanized, for fear of the galvanized steel giving off supposedly deadly fumes.

    in looking into it, it became pretty clear that galvanized steel used indirectly couldn't reach temps required to give off those fumes, and that even if it did, the fumes are not deadly.

    but the odd thing that became apparent was that stainless steel at the temps being warned about gave off far more dangerous fumes than galvanized ever could. nickel and chromium being the big culprits.

    the materials safety data sheet for stainless (although there are lots of types of stainless) spelled out that the fumes are far worse than galvy fumes. i don't think you will hit the sustained temps required, but i'm just mentioning the concern. i think it's an overreaction whether it's for stainless or galvanized, but of the two, stainless would be worse.

    it will be interesting to see if you get any dire warnings from our resident "canaries in the coalmine"
    ed egli avea del cul fatto trombetta -Dante
  • BBQEdBBQEd Posts: 63
    The outer skin on my smoker is split horizontally to allow for differential expansion. I would say the inner assembly expands around 3/16 to 1/4 during a typical cook, at least that's how much the upper section of the skin moves up the lower section. I used shop drops to build the smoker so I couldn't be too choosy about the grade of material used.

    From what I can see the firebox appears to be holding it's shape very well. I didn't feel stress relief was in order so it wasn't done.

    Unlike the Egg I haven't taken it "nucular" yet. In fact it hasn't even been above 400 deg.

    Pictures can be seen here if interested
  • BBQEdBBQEd Posts: 63
    Stike, you've piqued my interest. Any metallurgist types out there that might know at what temps this will become an issue of concern?

    I would have guessed that SS would be much less of a concern than Galvanized.
  • fishlessmanfishlessman Posts: 23,020
    from a welding standpoint most studies ive seen say stainless is more of an irritant than a problem from inhaling the fumes. they will tell you that welders have higher lung cancer rates but having been around this stuff my whole life theres alot more welders are exposed to than just welding fumes.
  • stikestike Posts: 15,597
    welding temps is what is warned about in the MSDS.

    lump will hit 1800, maybe 2000 for short times.

    but what's arc welding? 3000 plus?

    i think it's a non-issue on all counts, but you'll see much angst expressed about aluminum and galvvanized fumes (we've even had warnings about aluminum foil), but for some reason, folks treat stainless like it's some magic crystal with a healing power of +10 health points (non-sequiter, half-assed reference to dungeons and dragons)
    ed egli avea del cul fatto trombetta -Dante
  • BBQEdBBQEd Posts: 63
    I've asked our QC to dig up MSDS' for Inconel and SS. I probably should have explored this much earlier but I'm still very curious. I'll get better information when our welding engineer comes back from vacation.
  • stikestike Posts: 15,597

    i just think that the warnings about some metals here are out of proportion to the reality, and that generally stainless is seen as being some magic elixir.

    i went to buy some magnets to hang my kitchen knives. got some run of the mill german stainless knives.

    guy at the store was much older, much wiser, told me that stainless wouldn't stick to a magnet. i nodded and said "well, the kitchen knives will stick, anyway, where are they, do you carry them (magnetic tool holders, for a workshop)?" he reiterated that the knives wouldn't stick.

    when he found them for me, he said that i could take them back when they didn't work. i had a knife in the car (i was getting them sharpened at buccis next door), and wanted to make sure the thing was strong enough, because i was mounting the strip vertically, with the knives horizontal. bought them, got them to the car. tried the knives on them


    stuck nice and solid.

    i know you know this, being a metal dude... but when they drop-forge them, or if you even bend stainless, it will allow it to be magnetized. and the stainless knives will still get rust spots... it's more "stain resistant" than stainless.

    it's like pressure treated wood. people have ascribed far more merit to it than it actually has.
    ed egli avea del cul fatto trombetta -Dante
  • stikestike Posts: 15,597
    frankly, i think worrying about fumes from metal in the egg is a waste of time.

    if you really want to be safe, a person shouldn't run the egg at all (he said, being facetious). you might get fumes from stainless on rare occasions, and you might get it from galvanized metal, but you ALWAYS get carbon monoxide. and it is in high quantity, and far more dangerous.

    a person needs to ask themselves how it is they are going to be affected by stainless (or other fumes) but not by the CO. if the thing is properly vented, you are fine. and if not (if you make a habit of breathing directly from the top vent, for example, or burning it in an enclosed space), the CO will kill you before you notice any effects from the galvy or stainless.

    the CO is the only 'real' issue, any other worries about fumes from the egg are misplaced and irrational.

    not to be a killjoy, it's just well-intentioned but erroneous risk-assessment to worry about one thing and not the other (more dangerous) thing
    ed egli avea del cul fatto trombetta -Dante
  • BBQEdBBQEd Posts: 63
    I was speaking with a metallurgist from a company we are doing business with and decided to ask him his opinion.

    Roughly from our conversation....

    Inconel is much better to use in the firebox than SS as Cr not Ni would be the problem at elevated temperatures.

    His belief is that Cr in SS isn't a problem until the oxidation limit of the material is reached, ~1500 deg F for 304. He like me, thinks I would be hard pressed to get the firebox at 1500 degrees and that it would be easy to tell because oxidation on the surface of the SS would be visible.

    We didn't discuss galvanized but I would guess the same would hold true for Galvanized bolts, one would just have to find the oxidation limit of the bolt to know when Zn would be released.

    Our welding engineer is pretty in the know as well so I'll corner him when he gets back from vacation.

    Thanks for bringing this up as I too thought that SS was the magic material to use when I fabricated my smoker, now I know better. The sad part is that I deal with people everyday that could have given me good information and never thought to ask.
  • fishlessmanfishlessman Posts: 23,020
    with my setup for pizza at 1100 to 1200 dome temps im getting oxidation on the spider that holds my inderect setup, it does get hot down there, but at temps that most are cooking at i dont think there is much problem at all. my spider is getting pitted
  • JeevesJeeves Posts: 461

    How much would you sell one for?
  • BBQEdBBQEd Posts: 63
    Which leads to the question of how much Cr in the cook would be considered unacceptable? I personally don't stand over my smoker when I cook, though I may if it were pizza, so for me inhalation would be much less than I experience when I walk through through shop. Is consuming it just a hazardous? If so what's the safe limit there? My guess is that exposure is very minimal, especially when I see guys welding this stuff 7+ hrs/day 5 days a week with little more than ventilation fans in their work areas.
  • fishlessmanfishlessman Posts: 23,020
    ive read a few things about welding fumes over the years, even breathing it it doesnt stay in the lungs, it dissapears after a few months. even galvy poisoning seems to clear up after awhile from the lungs. now have you walked thru a big trash gen plant, you can taste the metal in the air, that cant be good.
  • stikestike Posts: 15,597
    when your dome says 700, the lump is at 1200+. likely hotter, maybe as much as 1800 degrees. and that's where the lump is.

    here's the odd thing. when your dome says 250, your lump is at, well, 1200 or so.

    carbon burns at a sort of minimum fixed temp of 110-1200 degrees. with more oxygen flowing, you'll see lump that hits 1800 or better. your SS fire grate would in direct contact with that
    ed egli avea del cul fatto trombetta -Dante
  • stikestike Posts: 15,597
    if you haven't been killed by the CO (which is ALWAYS present), how is the chromium going to affect you. i'll say again, you';ll never have an issue with any metal fumes, because to inhale them, you'd also be inhaling the CO, and that would kill you before you ever complained of the galvy fumes

    non issue.

    i'd be more concerned about thinking that the stainless will be any better than the cast iron, because you will have oxidization anyway at the temps lump is at. dome temp is irrelevant. your egg is always running at 1200 or better. it's just a question of how much lump is at 1200, and how much that raises dome temp
    ed egli avea del cul fatto trombetta -Dante
  • stikestike Posts: 15,597
    check the diffe between galvy fumes and SS though. galvy only gives you flu-like symptoms, which disappear in a day or so. you are safe to inhale galvy fumes for 15 minutes a day evn, according to the MSDS.

    but there are serious long-term warnings about SS, specifically chromium and nickel.

    but not for the egg. you'll never inhale them if your egg is running correctly
    ed egli avea del cul fatto trombetta -Dante
  • fishlessmanfishlessman Posts: 23,020
    we die from asbestosis before chromium and nickel has a chance to take us down. i wonder how long it will be before rutlandosis starts taking over because thats whats replacing the asbestos in this field.
  • stikestike Posts: 15,597

    i think you know where i stand on all this. hell. i have a dad that would burn PT wood, creosote soaked lumber, plastic milk bottles, gunked up pallets.... as a kid, i had to empty the woodstove of nails every week or so as it filled up.

    there's more harmful stuff passing through my liver than into my lungs. i really can't wrap my head around worrying about metal fumes from the egg. they are infinitesimally less dangerous than the CO, and hell, less dangerous than the steak you are cooking.

    i say, cook away. i'd buy a galvanized spatula if i could, and keep it clean by storing it in a coffee can full of kerosene. i'd shake the excess kerosene off before using it to flip the burgers
    ed egli avea del cul fatto trombetta -Dante
  • BBQEdBBQEd Posts: 63
    Are you sure lump burns that hot?

    I believe this tube was around 1500 deg F when the picture was taken...

  • BBQEdBBQEd Posts: 63
    fishlessman wrote:
    ive read a few things about welding fumes over the years, even breathing it it doesnt stay in the lungs, it dissapears after a few months. even galvy poisoning seems to clear up after awhile from the lungs. now have you walked thru a big trash gen plant, you can taste the metal in the air, that cant be good.

    I guess I'll feel lucky that I've never been in a garbage burner. But I have spent a lot of time in Basic Oxygen Furnaces and that is not a pleasant experience either...
  • stikestike Posts: 15,597
    it's carbon. what temp does carbon burn?

    1800 is entirely normal. but all of this is MOOT. well, moot as far as health is concerned (from the whole histrionic chicken little metal-fume perspective anyway). but it ain't moot if you're concerned about the SS oxidizing and loosing its properties.

    that pic shows red/pink. glowing red isn't frankly very hot (relatively). any other color is hotter (orange, yellow, white, blue). lump will get white hot. that's 2000+ right in the center of the white lump

    lump is highly pure carbon, and ignites and keeps a sustained temp of something like 1100-1200 degrees. keep a good draft though, and she'll hit 1800 easily.

    there are some guys that forge steel with wood lump, instead of coal. and they can get hot enough (forcing air into the lump) to melt iron

    if you are wondering what temp the lump gets to, your answer lies in the fact that you are replacing a cast iron grate which has deformed and cracked. i think we all know that doesn't happen at 700-800 degrees (f), and yet you have a deformed and sagging cast iron grate.

    just get a new one, so we can all move on.

    ed egli avea del cul fatto trombetta -Dante
  • BBQEdBBQEd Posts: 63
    "but it ain't moot if you're concerned about the SS oxidizing and loosing its properties."

    My point exactly. I realize this forum is dedicated to the egg but I happen to have an egg and a recently built Stumps clone, the entire innards of the clone are 1/4" and 12Ga. SS as can be seen in the pictures shown in the link from one of my posts above. I'm about 3/4 of the way through the "design" of another smoker/grill and thanks to this thread am now considering a material change. Inconel is out of the question even though I believe it has dropped to around $19/lb which makes it far too expensive to use for something larger than a small grate. I can openly take SS and Carbon drops for government work but I don't think the owner would appreciate it if I started taking big Inc drops for government work.

    In any event I also took the blind SS is the end all approach.

    This thread has given me a lot to think about and for that I am extremely grateful, pun intended.

    Thanks Stike and Fishlessman you guys have opened my eyes.

    FWIW the cast grate on my Egg is > 2 yrs old and has seen dome temps in the excess of 600 degrees so many times I can't count them and it still looks fine, the gasket on the other hand...


    My old grate, 1/2" 304SS, plasma cut to shape used around 15 times. Max cooking temperature 400 Degrees.

    A close up of a corner of the grate..

    My latest grate attempt, SS don't know what grade found in scrap pile leftover from customer supplied refractory mesh, used twice max cook temp 350...
  • stikestike Posts: 15,597
    let us know if you find a "grate" solution (that was a pretty bad pun.... hahaha).

    sounds like you managed to understand where i was coming from, despite my many paragraphs. hahaha nice work hanging in there.

    you are right. i was trying to say that the SS itself might not last any better. i wasn't really thinking you were worried about the fumes themselves. ...but there are a lot of folks who mention it from time to time, so i beat that horse a little harder than i needed to.

    keep us posted. i think fishless found the ideal solution, but most of us don't have a scrap pile of monel laying around..... bwah bwah bwaaaaah :huh:
    ed egli avea del cul fatto trombetta -Dante
  • fishlessmanfishlessman Posts: 23,020
    on the other hand i have some plate that burns white when lit and could probaly cook a pizza in under a second. :laugh: that could be my new pizza grate. i think its heavy with lithium but not sure really what its made from. i dont think the egg could handle it, i had some in a bucket of water, threw a match at it and the whole thing vaporized in a 30 foot tall flash and it was just some dust i took out of the saw after catching that on fire as well :whistle:
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