Do I need to vent a semi-insulated firebox? Will it explode?!

[deckerbbq]

I'm building an offset smoker out of a old 500g propane tank. I sliced off about 1/4 of it to build the firebox, and it was just too large of a diameter to work with (35") so i slid a 24" pipe inside it leaving about a 6" air gap.
Here are some progress photos:

and from the back:

Those 4 supports are temporary. I'm planning on cutting off that excess 24" pipe to make it flush with the rest of the firebox, and then sealing the whole thing up with 1/4" plate except for a half moon opening on the 24" pipe where it meets the cooker.

Now, my real question is, am I building a bomb? There will be a 6 inch air gap there that's totally sealed and is certainly going to heat up and expand. Do I need to vent it? I've read a lot and watched a lot of videos and this hasn't ever come up.

Thanks in advance.

 

[DanMcG]

Dang that 24" pipe is thick!
It's going to take a while to heat that mass up.

I'm wondering if you would want to cut an air inlet at the bottom and vent it into the smoker at the top.
I have no idea, just throwing it out there.

 

[kruizer]

I would vent the bottom of it so as to release pressure and prevent water from collecting in the void space.

 

[smokin peachey]

I built my firebox the same way and have a hole at the bottom of the firebox tank to allow moisture out and release pressure.

https://www.smokingmeatforums.com/threads/500-gallon-tank-build.250565/

Good luck with your build

 

[deckerbbq]

Dang that 24" pipe is thick!
It's going to take a while to heat that mass up.

Yeah, the whole thing is massively overbuilt. The tank is from 1945, and is half an inch thick. After I lopped the section for the firebox off, its 9 feet long. That 24" pipe is schedule 80, I think, and is around 3/4". Firebox will be about 4 feet long.

I plan on just loading it down with wood before I go to sleep, and having a nice coal bed to work with when I wake up to start cooking super early in the morning.

Thanks for the advice on the venting. Ill put a hole in the bottom of the box and hopefully not explode.

 

[smokin peachey]

wow 4’ firebox. I used 1/2 a 250 gallon tank.

Keep us updated with pics

 

[pigbark]

wrap the 24'' pipe with a Cera wool Blanket aka fire blanket..might take a couple but its worth it in the long run.. it will hold heat and know one will get burnt if they touch the outside of the FB.. very efficient stuff... dead of winter, you can roll smoke and not use as much extra wood..your recovery time will be super low as well..

 

[eddiememphis]

Should be pretty ease to move around... with a CH-54.

 

[deckerbbq]

wrap the 24'' pipe with a Cera wool Blanket aka fire blanket...it will hold heat and know one will get burnt if they touch the outside of the FB

How am I supposed to keep my coffee hot if I cant rest it on the box?!

 

[pigbark]

How am I supposed to keep my coffee hot if I cant rest it on the box?!

lol - put it in the fire box..

i run a couple different Kilns, 1 inside "electric 2200 F" and one outside "propane" the outside kiln is a simple galvanized garbage can lined with cera wool.. i have hit some pretty high temps with it, 1700s ... i have made hard fire brick glow but i cant make the cera wool glow.. good stuff..