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[tinner]

Has anyone ever recorded the fire box inside temp. while at a full burn? How about the gasifier tunnel from the outside? The reason I am asking is that I have the chance to pick up a FREE pc. of 30" dia. x 42" .375 wall 304 stainless pipe. If I were to get this I would be using 1/4" A36 for the ends and tunnel. And 10ga A36 for the water jacket. It would call for the use of 309l wire for the dissimilar metals. After a brief conversation with a mechanical engineer and telling him about the tunnel being lined with fire brick. He thought it would be ok. I told him I would try to obtain the temps for him.

Thanks!
Bob

edited to add: I have decided not to use the stainless at all.

[Scott7m]

A gasifier will burn over 2000 degrees.  304 stainless however IMO is not a good choice for a stove.  304 grade stainless is much more brickle than let's say a 409 grade, heatmaster uses 409 because it is flexible and don't crack along the welds like 304 does sometimes. 

There is also several pics out there of stainless getting a crowfoot like cracking all over it on owb's.  My cousin has a hardy and has had the firebox replaced 2 times and they both just looked shattered like. 

Just my opinion, but that was regular owbs that get no where near 2000, I'm sure wear and tear and stresss on the steel would be much higher with temps over 2000

[tinner]

I agree with what you are saying. But I wonder if the fire box only gets to 800*+/- and the tunnel where the real heat is 2000 +/- but lined with the bricks and the water jacket surrounding all of it do you think the expansion and contraction would still be as high? Now I am sort of playing devils advocate here as I do agree with you but kind of wanted to see some other thoughts on it.

thanks again

[Scott7m]

Yea I donno, I'd just hate to put all the time and work in it to have it not work or fail.   

That's just my opinions based on what I've seen and learned in messing with this stuff.

[RSI]

A gasifier will burn over 2000 degrees.  304 stainless however IMO is not a good choice for a stove.  304 grade stainless is much more brickle than let's say a 409 grade, heatmaster uses 409 because it is flexible and don't crack along the welds like 304 does sometimes. 

There is also several pics out there of stainless getting a crowfoot like cracking all over it on owb's.  My cousin has a hardy and has had the firebox replaced 2 times and they both just looked shattered like. 

Just my opinion, but that was regular owbs that get no where near 2000, I'm sure wear and tear and stresss on the steel would be much higher with temps over 2000

I doubt you would see the cracking problem on 3/8" thick SS.

I am not sure how you want it to work but you would get really bad heat transfer through the stainless. Most boilers that use 300 series SS are less than 1/8" thick. I have seen stainless steel in insulation charts before because it has such poor conduction properties.

What is the scrap value of stainless right now? A while back it was over $1 a pound. If it is enough you might be able to scrap it and use new steel and come out ahead.

[Scott7m]

RSI, hardy are 16 gauge, .0598 thick. 

[tinner]

Thanks guys!
Like I said in a previous post I was pretty sure of the direction i was going to go. I just needed a little push. I have not checked on the scrap price because I will probably use it for storage. I am going to go 1/4" black iron. I am just in the designing stage at this point and plan on bouncing lots of thoughts past you folks. Such as:
In looking at different tunnels I was hoping for some comments on these









If possible would a Moderator rename this thread to Tinners Project.....Thank You

[martyinmi]

Looks like you've one tunnel going forward and two back,right? I'd just go with one tunnel going back with nozzle 1/3 of the way back from the front of the primary burn chamber. Simple,tried and true, easy to clean, works.
   I would love to have that piece of pipe. What is it from? It would have to weigh 3 or 4 hundred pounds, wouldn't it?

[tinner]

I see that the new P&M 350 has gone with a single tunnel. I will have to think about that. Seeing how you say it is tried and true and they are doing it, it should be good enough for me...

The pipe is a pc. of scrap from a steam fitting job that the company I work for just completed. It is rolled and single seam welded 304 st. st. I was told it cost $300.00 per foot new. 30" dia x approx 42" The owner gave it to me and so I will need to make use of it one way or another.   
The only Black Iron scrap they have right now is 20" dia. 
But I am not in a hurry so I will design mine in a couple of different configurations and see what happens when it is time to start working on it.
I am still on a 5lb. lifting limit from knee surgery so it will be awhile.

Thanks for the title change and reply. It will keep the forum cleaner by keeping my stuff in one place. 

[tinner]

Looks like this coil might be just a tad too big.
 


Besides, it has a couple of holes in it
lol

[tinner]

Found my chimney pipe today.
 

[tinner]

@ martyinmi

I knew I had read about the 250's being sent with no upright bricks in them. I did not until now realize it was yours...lol
How / where are they injecting the air into the gasifier tunnel?
I am thinking of running a pipe or tubing from the rear, through the fire box and into the secondary chamber.

Thoughts / pics?

Thanks!

[jackel440]

I have a thermo couple in the gasification chamber just pass where the nozzles are.I have seen a high of 1300*at my thermocouple.That was like a perfect burn as it doesn't usually run that high during normal operaton.I wish i would have placed the thermocouple tube right in the nozzle path now.Oh well as I was trying to do alot when I built my gasifier.
I wouldn't use the s.s. if it was me.We have all kinds of issues with our electric vacuum furnaces at work.I have to weld those water jackets all the time as they crack.
You can weld the dissimilar metals ,but why build with something that can cause future head aches when you need it to be reliable and heat your home?
I would suggest building with materials that have been proven to be reliable and easily repaired at inopurtuned times.
good luck

[tinner]

Thanks again,

Yeah  have decided not to use the s.s. in contact with either of the combustion areas. I may still use it for heated storage though.

 

[Zaney444]

304 expands around four times as much as mild steel.. id be worried mixing metals with different expansion rates could cause early failure.. i was planning on running my exhaust in 316l sch 10 i had but more i thought about having to tear into it to repair it i went with carbon and a weld that would pass in a nuke plant haha