Steel Dome Oven Other Oven Types Discuss Steel Dome Oven in the Pizza Oven Design and Installation forums; Hey Wiley - How are you coming on the paint? I used some smooth Stucco-type finish from Dryvit that remains ...

[christo]

Hey Wiley -

How are you coming on the paint? I used some smooth Stucco-type finish from Dryvit that remains flexible. So far so good. There was one area on the foundation that had a hairline crack and I have not seen it since I coated it.

The color seems to be holding it's own.

Good luck.

[Wiley]

Christo, Actually I haven't gone any further with that problem. We've been busy....

I've been getting ready to haul my boat. We're hauling out tomorrow and hopefully we will only be out a week. Lots of lost time what with weekly parent visit and grandkid's birthday on the weekend so it might be longer. That's of course assuming we don't find any major problem(s). But we took her to the dock today and off loaded extra diesel and water and sails and such like, both my wife and I agreed we need to spend more time on the water. We want to work my/our schedule so we get more time on the boat. Priorities!

I also cleaned the mooring chain last week and decided I want to replace it before winter. So once we are back in the water I will be replacing the top pennant of her mooring (20 ft of 1/2 inch chain) and probably add an additional 3 to 4 ft of the heavy chain (1 1/2 inch / 9+ lbs per link stuff) so I don't have to make these swaps at low low tide.

But soon as that's done I plan on finishing up the pavilion and finding some sort of elastomeric paint, how thick (viscosity not film thickness) is the Dryvit material? I looked at some hypalon paint, which I know is tough and which will accept an overcoat of the paint I have. A bit on the pricey side though.

Bests,
Wiley

[christo]

Good to talk to you. I've been away too long!!!

The stuff I used has some sand in it - more like a smooth stucco finish. I'm not sure if they have a smoother finish.

I'm hating I sold my boat - but not so much....

I'm heading down to FL soon to do some sailing and fishing with some old friends (who still have their boats!!)

Please send some pics of the pavillion - sounds very cool.

Take care,

Christo

[firebug]

Hey wiley,

I'm new to this thread and you have answered many of my questions, I plan on building a trailer mounted wfo,my plan is to build metal base welded to trailer, them form up base with cement and perilite then one layer firebricks for the floor, take 1/2 steel bent for a big barrel vault 4x6'.build a dog house around it fill it with 6'' or more of perilite,I want to do a hearth in the front,,,,all done with fire rated materials I want few moving parts I think this could work ,what are your thoughts?

[Wiley]

Hi Firebug,
OK, first thoughts and assumptions on your query:

It would appear you are considering using no other heat retaining medium other than the steel plate bent to form the barrel vault for the ceiling. Without knowing the exact shape you are envisioning it would be hard to get an precise weight. However, steel weighs about 40.8 lbs per sq ft one inch thick (board ft). So a flat sheet 4' x6' and 1/2 inch thick would weigh about 490 lbs and in the interest of getting some sort of figure with which to work (ball park figures) doubling that for the curve of the ceiling and the ends etc would give us a figure under 1000 lbs. My gut feel is that that is too little a heat reservoir/ heat sink for that large a volume. I suspect it would heat up fairly quickly but also cool down quickly as well. We don't get something for nothing. BTUs need to be liberated; the heat transferred into the heat sink then released back. It's the released back that we are using to bake with in addition to the heat from a ongoing fire to maintain a certain searing/reflection/direct radiation in the case of baking a pizza. I am not a thermodynamics engineer so alot of what I am saying and thinking is "gut feel" (and we all know how much that "gut feel" can get us into trouble). But if one knew the heat capacity of steel and compared it to the heat capacity of firebrick/stone/clay/terracotta one might be able to produce a better answer as to "Would this work?" And by "heat capacity" I mean how much heat (BTUs) can this material soak up/contain/hold? and how fast does the material cool down, give up that stored heat?

So, I suspect such an oven would heat up very fast and but that controlling the heat might prove problematic.

I'm sorry that is not much of an answer. I used the steel dome of my oven as an uncrackable, unspallable, hard to damage and smooth interior form to support the heat reservoir, not as a heat sink itself. I suspect that my steel interior more quickly distributes heat to a larger surface area of the heat reservoir than straight bricks do, however, that is once again, "gut feel" and I have no hard evidence to support that supposition. I do have evidence that a steel dome doesn't crack, that in advertantly striking the interior with a peel results in minimal (read that as no) damage.

Hope this helps,
Wiley

[firebug]

Wiley,

Thank you for you response,I guess I was hoping the perilite on top of the steel would help retain the heat keeping the dome hot I planned on 6 inches on the sides and 12'' on top of the barrel,but it sounds like what I need is fire bricks on the inside of the barrel as a heat sink,or do you think lots of insulation on top of the dome would suffice? another ideal I had was to weld some channel inside the dome so i could slip in firebricks throughout the entire inside, all the brick would be free from mortar etc,this means no cracking and falling apart.I need a oven that can do major volume and fast,and I have heard to many horror stories with all brick ovens busting apart on the road.thanks for all your insight and look forward from hearing back.

[JoeyVelderrain]

Originally Posted by firebug

Wiley,
I need a oven that can do major volume and fast,and I have heard to many horror stories with all brick ovens busting apart on the road.thanks for all your insight and look forward from hearing back.

sounds like this would be perfect for you.
2stone Pizza Pro portable high heat pizza oven (propane)

[Wiley]

Firebug,
First , thanks for the brain teaser, I have enjoyed messing with the figures in my head :-) And now to try and put them on paper.... So,

Some further thoughts and assumptions:
Let's assume a semicircle x-section for the proposed WFO, with the 6 ft being the long dimension and the 4 ft being the diameter. Pi x D = 12.56 ft. and that divided by 2 gives the length of the half circumfrence. And that times the 6 ft length gives us 37.7 sq ft of 1/2 inch plate. Dividing that by 2 gives us 18.8 square ft of one inch plate and then taking that times 40.8 lbs/sq ft gives us 769 lbs.

So just for comparison lets take that same square footage of ceiling and make it out of 4 inch thick refractory. So 37.7 sq ft x .333 ft results in 12.55 cu ft. Now once again ball parking: a cubic yard of stone weighs a ton. So 2000 divided by 27 gives us 74 lbs per cu ft. 74 times 12.55 gives us a figure of 929.6 lbs. We're ball parking so lets say 930 lbs for the refractory and 770 lbs for the steel. 160 lbs difference. Really not that much. It wouldn't take but two 80 lb bags of concrete to have them the same weight.

So do you have a 6 ft "pup" of the pipe used in the Trans Alaska Pipeline? If memory serves that was just over one half inch thickness and 48 inches in diameter? Although a graph of heat up and cool down versus time would, I suspect, be more peaked and show a shorter "linger time" at the top for the steel, all in all it might actually work. "Gut feeling" being inaccurate once again better "to put a pencil to it" and get some numbers.

Bests,
Wiley

[firebug]

Hey Wiley,

Your giving me some more good info,fist I thought about a large pipe cut into half,but I don't want a 1/2 round arch I want an elliptical arch which is more suitable for a barrel vault (correct me if I'm wrong) my legs on each side will come up 12'' and come up 10'' more in the center creating the barrel arch,I think this is proper for the size of my oven 4x6 deck.there is a company in Portland that will bend the steel for me and weld the back on , the front will have a smaller opening in it then welded on.then I will build brick hearth and chimney,then the task of covering the metal vault begins,what would you recommend I use to do that?thanks again for your help

[Wiley]

Firebug,
When you say "covering the metal vault" I'm thinking you are meaning the welded up firebox? And do you mean after it is placed upon the base (firebrick over perlite/cement insulation)? If that is what we're discussing, and since this is an experimental WFO, I think I would be prone to make things simple and in such a manner that one could easily get back to the steel vault should you find that you need more thermal mass. I like your idea to build the enclosure such that you can fill it with loose perlite. It's not as expensive as kaowool or other ceramic blanket and if you need to do work on the vault all you would need is a clean shop vac and some plastic trash bags and you can get the stuff out and still have it reuseable. Space isn't a concern so 8 or more inches of dry loose perlite might be all you would need.

Your mention of Portland brought this to mind.....and this is a wild idea in that it was something that came up last winter and I have no idea what the situation is regarding it at present. But there was an offering for free supersacks filled with perlite at the airport. If I remember the story right somebody had the stuff (100,000 lbs) stored there and couldn't pay storage they wanted/needed it gone and fast. Had the weather been better I and a friend were going to participate in the deal. I think I would give a call to the airport and ask a few questions as to who got the stuff and where did it go. There is the off chance that somebody scooped up the deal and would like to be rid of it themselves. Or perhaps sell what you need less expensively than retail, because I think you are going to need alot. Check archives for 11/19/08 a posting by Jed. The Craigslist posting is dead but somebody will know something at the airport, (and I'm fairly certain it was at the airport. But then again my memory is good, just short).

You might start your own thread as this will be a WFO alot of people I think will be interested in following.
Bests,
Wiley