Best practice for joining 55 gallon drums

I've done quite a bit of searching of the forum on this topic.  It seems there are a lot of different possible ways of doing it.

The build I'm envisioning is based on Matt Walker's SuperHot J - 8 inch.

I plan on using open head 55 gallon drums.  The top of the riser of the 8 inch SuperHot J is about 35 inches above the base, so I will need more than one barrel. I plan on having the bottom barrel extend down even with the bottom of the burn tunnel.  The bottom barrel (probably less than a full barrel) will have two rectangular cutouts, one that slips over the burn tunnel, the other for the attachment of a transition section leading into a bench bell.  I'll probably have the flue exit the lower half of the bell adjacent to the drums to assist in generating draft in the chimney.  Burn tunnel and bell will be clay brick set with clay sand mortar, the bench bell top will be some kind flat stone or cast concrete.

I would like the option of doing some cooking on top of the drum as well as heating water for additional humidity, two full drums would be too high that - 68 inches.  A drum and a half would be 51 inches, still a little high, but probably OK, and it would give me about 15 or 16 inches of clearance above the top of the riser.

So finally I'm getting to my questions on joining the barrels!

- for the top full barrel I'm thinking I will use it right side up - using the removable head as the cooking surface, held in place with a barrel band and ceramic fiber gasket. Should I saturate the gasket with clay slip before I clamp it, or is that overkill?  I also plan on cutting out the bottom of the top barrel about 1 1/2 inches in from the outer diameter,  leaving a hole about 21 inches in diameter, the outside diameter of the riser is 10 inches, so I will have 5 1/2 inch clearance from the riser all around if I center things perfectly.

- for the lower half barrel I'm thinking about using the the bottom half of the barrel, flipping it upside down, cutting out the bottom as described above for the top barrel.  I could then place a ceramic fiber rope between the barrels.  Then clamp the two barrels together with a barrel band and gasket, possibly saturated with clay slip.

Does this seem like a reasonable plan?  Do you see problems or have concerns?  If you have suggestion for a better solution, please let me know.

Thanks.

Hi William;
No gasket, no slip needed.  
I use two barrels joined together. Initially, I was concerned about leakage there.
Peter assured me that any tiny leakage would quickly stop as the draft started and it went to negative pressure.

I accepted his word.  (He is the Master Rocket Scientist after all!)
I sat one barrel on the other and then stuffed morgan superwool in the band.
This worked, in that the band sealed up OK but it did still have little smokes until the internal pressure changed.
Several times now I have removed the barrels. I no longer even bother putting super wool in the clamp!
Yes, with a completely cold start small amounts of smoke seep out and then it quickly stops.
Working with an RMH is a different beast than a traditional box stove.
A small leak on a box stove would continue to leak... not true with an RMH.

Hi Thomas,
Wow, thanks for that information. I never considered negative pressure!  QUESTION- Does this negative pressure exists throughout the whole system (from feed to top of chimney).  I assume it does, so if there are any tiny gaps in the masonry joints of my bench bell they should not leak either once draft is established. My masonry skills are less than perfect and I have/had a real concern about leaks.  Also, I know cracks in clay/sand mortar can occur over time.

Hi William;
Correct, any leaks you see during a cold start will quickly disappear!
And I promise you that you will indeed have leaks on your initial start-up, but only until things dry out and warm up.
After your initial moisture has evaporated and your mass heats up you will not have a single smoke seep.
RMHs are awesome!  You will love yours!