The Texas BBQ Forum

I am in the planning stages of converting a 500 gal propane tank to an offset smoker on a trailer. I will be cutting 1/2 of one end off the tank to mount my firebox to the end of the tank. My rough estimate for the firebox size is 36x36x36. I plan on insulating the box and the door. I'm thinking 1/4 inch steel inside walls and 3/16 on the outside walls with a minimum of 1" ceramic insulation between. Any advice would be welcomed. How large an opening do I need for the throat? I plan on placing the bottom of the throat about 1 1/2 inches above the bottom of the cook chamber to keep grease out of the firebox. My plan is for a 1/2 moon opening, but being in the planning stages, I am open to suggestions. This is my first build and could use all the advice I can get.

You may want to send KAM a PM on here. He will get you pointed in the right direction.

banditbbq wrote:I am in the planning stages of converting a 500 gal propane tank to an offset smoker on a trailer. I will be cutting 1/2 of one end off the tank to mount my firebox to the end of the tank. My rough estimate for the firebox size is 36x36x36. I plan on insulating the box and the door. I'm thinking 1/4 inch steel inside walls and 3/16 on the outside walls with a minimum of 1" ceramic insulation between. Any advice would be welcomed. How large an opening do I need for the throat? I plan on placing the bottom of the throat about 1 1/2 inches above the bottom of the cook chamber to keep grease out of the firebox. My plan is for a 1/2 moon opening, but being in the planning stages, I am open to suggestions. This is my first build and could use all the advice I can get.

Here is a filled out link to the calculator I would use.
Link to BBQ Pit Calculator
I would go 2" minimum insulation.

The pit is 50 miles from home in a shop where I have access to heavy lifting equipment. We've been working away at the pit. We built a 3'x3'x3' firebox and insulated all sides but the bottom. The smoke stack is an old 9" dia oxygen tank. I don't have a clue how many hours we have in it. It's been very tiring when we can spend time on it, but it sure is fun. I can't wait until I get to bring it home and fire it up for the first time. We'll be recessing it into a 16' trailer and welding it in place. After that I can bring it home and finish out all the details in a little more timely manner.

I could be wrong but that exhaust stack looks too short to me.

Chasdev wrote:I could be wrong but that exhaust stack looks too short to me.

Thanks, I'll double check the calculator, but I thought we had it long enough since it is 9.25" I.D.

banditbbq wrote:

Chasdev wrote:I could be wrong but that exhaust stack looks too short to me.

Thanks, I'll double check the calculator, but I thought we had it long enough since it is 9.25" I.D.

I double checked the calculator, stack is fine because it's 9" in diameter.

I like everything I see there just one problem.... its not mine....
the extra large fire box is a good thing in my opinion, I have cooked on pits like that. Hopefully you have the exhaust at or below the grate level.. are you going in with tuning plates? some day I'm gonna buy me a gas hatchet and a cracker box & build me one of them... in past we my employees and self bought several feet of large pipe and built ourselves each a pit. There are still all of them somewhere in existence as they will never rust or burn out due to their thickness.

Looks awesome!

spacetrucker wrote:I like everything I see there just one problem.... its not mine....
the extra large fire box is a good thing in my opinion, I have cooked on pits like that. Hopefully you have the exhaust at or below the grate level.. are you going in with tuning plates? some day I'm gonna buy me a gas hatchet and a cracker box & build me one of them... in past we my employees and self bought several feet of large pipe and built ourselves each a pit. There are still all of them somewhere in existence as they will never rust or burn out due to their thickness.

The exhaust is at the grate level. I welded in some angle to hold my tuning plates. I had them cut this week from 1/4" steel. They are 7.5 inches wide. Got my money pit mounted to the trailer this weekend. Brought her home so I could finish her up in a more timely manner. Been having to travel 60 miles one way each weekend to get some work done because I didn't have anything that would lift something this massive.

BigThicketBBQ wrote:Looks awesome!

Thanks! I can't wait for a test run. Few more things to finish up, then I get to light the fire.

Got the money pit welded to the trailer and brought her home where I can finish her up.

Looks great, can’t wait to see it smoking! Going with the standard black paint?

That unit is going to serve you well. It will outlast the trailer.

Get it Brother