200 Gallon Oval Oil Tank Reverse Flow Smoker Build - 55 Gallon Drum Firebox

[fatbastard09]

Hey guys, its been years in the making but I am finally starting on the build using several salvaged items out of an old garage that a friend purchased.  I received several items that I could work into a plan, but have settled on the using the 44" x 27" x 48" oval fuel oil tank as the cook chamber (its never had oil in it), an old school version of the Vogelzag 55 gallon drum firebox kit from the garage, and a brand new 55 gallon drum (it had OJ concentrate inside of a food grade bag in it) for the fire box.  I've been looking online for the 48" wide version of this oil tank to see if anyone else has made a build out it to get some ideas, and could only find the 60" versions that are 275 gal.  Based on the dates on some of the other items that were left in the garage all this came from, this stuff may be over 50 years old but it is all still in really good shape.  I am calling mine 200 gallon based on calculations, the name plate doesn't list the volume.  I've done the calculations on the firebox, openings, stack, etc. using both Feldon's online calculator an the calculations recommended here on SMF for comparison.  Since I am using components that I already have (or can get for free) I realize I am not going to hit all the #s dead on and have been reading up on the implications on that.  So  far, I am cool with what I came up with in terms of hitting the recommended specs as being worth giving the project a shot. 

The one big question I had right out of the gate was the assumptions used in Feldons and on the SMF calcs on cook chamber size.  The way I ran my #s I originally used the entire oval tank volume of 200 gallons for the cook chamber, but I kept wondering if since I am putting in a RF plate, shouldn't I just be using the volume of the tank above the plate since that is technically the cook chamber.  I started running #s both ways.  Once I figured out I wasn't going to be able to use my first option for the firebox (it was only 44% at best, but man was it cool), I started questioning which cook chamber volume (total tank volume or volume above the RF plate) I should use when calculating the area of the cut outs between the firebox and cook chamber after solving the rest of the #s using my back up firebox (the 55 gallon drum).  What I really was trying to do with the calculations was to see if I was wasting my time on something that wasn't going to work and if not try to maximize what I can with the rest of the calculations.  In the end, I think I maximized my design the best I could with the materials I have on hand which was my goal from the get go.

I don't think I will get more than a handful of opportunities a year to fire this thing up, but when I do I am hoping I can reliably maintain heat.  Based on some of my #s, it doesn't look like I have everything ideal (except the cost of materials- the big stuff being free).  I am not overly concerned about fuel consumption, that's one thing I have covered for a long, long time with wood from several orchards that I have access to and a rather large cache of charcoal brikets.  Please take a look at what I am laying out here and the calculations below (I am posting a pic of the calculation spreadsheet, but from what I read that might not show up right away since this is only my second post) and let me know if this looks doable the way I have it laid out.  Any help and/or advise is greatly appreciated.

200 Gal Oil Tank Reverse Flow Smoker Calculations

• fatbastard09
• Feb 26, 2017

Thanks!

FB

 

[daveomak]

Feldon's uses the size of the FB for it's calculations....   The SMF calculator / tutorial uses the CC for it's calculations...

Since you are heating above and below the RF plate, use the entire CC for calculations..

 

[fatbastard09]

Using the entire volume of the cook chamber makes sense, thanks for the clarification.  I got started with the firebox over the weekend, got the hole cut out for the door.  So I guess I can say I have "officially" started this build.  I haven't bolted the firebox door to the drum head yet, I am still debating on whether or not to have the whole rig sandblasted after I get it all on the frame or to clean up these rusted parts first.  I have to make some calls and get some quotes on that.

20170226_165552.jpg

• fatbastard09
• Feb 27, 2017

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• fatbastard09
• Feb 27, 2017

Thanks again Dave

 

[fatbastard09]

So I got all the bolts to attached the firebox to the head of the drum and decided I am going to sandblast the door in the shop at work and paint it before I put it on (will touch up after the projects complete).  When I measured the air inlet under the door I come up with ~ 23 square inches, much less than the 46" square I need.  I think I can put a small slide on the top of the door to get another couple inches but I don't think that is going to help much.  I am thinking I might have to put some lower and upper air inlets on the side of the drum up by the door to get to my #.  I am trying to stick to the 80/20 bottom to top as much as I can as well, but I also saw the recommendation to keep the upper air inlet across from the FB/CC cut outs, as you can see from the pictures that isn't really possible here. 

I had trouble finding details on SMF of other people's builds using a 55 gal drum a firebox like this using the search function to get some ideas.  Has anyone seen a similar firebox set up like this and if so how did they handle the air vents?

As I mentioned above, this whole project is going to be full of compromises since I am trying to maximize the use of available materials; so I am looking for input on how to make as best as it can be not exactly how you would do it if you had no limitations!

Thanks,

FB

Smoker Trailer Design 02.27.17.jpg

• fatbastard09
• Mar 2, 2017

 

[fatbastard09]

Couple ?s:
1. Any ideas on the upper air inlets asked above?
2. I cut the fb/cc openings, looks like there will be a gap when I weld them together due to the indent on the oil tank. Any ideas on how to fill them?

20170305_144713.jpg

• fatbastard09
• Mar 5, 2017

 

[metalmonkey]

Use some round 1/4" round stock to make up the difference. It's very cheap and you can bend it around as you tack weld it in place. Or you could just slice off the flange on the side of the tank where it is giving you grief.

 

[fatbastard09]

Sounds good, I will try the round stock. I am picking up the rest of the steel for my frame and racks this AM. I had hoped to weld the firebox and hinges on this weekend. Then cut the doors. The high is only 28 tomorrow, so not too sure if I will get to it. Oh ya, I have never laid a weld in my life so I was planning on practicing with scrap first. I bought a flux core welder for this project, we'll see how good a teacher youtube is...

 

[fatbastard09]

Update: On the upper air inlets, my thought was to go with gate or ball valves on both sides of the top (think 11 o’clock and 1 o’clock if the front of the firebox was a clock).  On the inside of the drum I would put a 90* elbow facing the fb/cc opening.   Problem I am having with that is sizing.   If I put two 1.5” ball valves the opening area is still very small, but I also realize the air velocity through that small of an opening is going to put some cfm’s across the top of that fire.   I am going to do some homework on those calculations, my math skills on airflow dynamics are quite rusty.

Still haven’t had weather that would allow me to weld the firebox on, I am following advice to do that before I cut the doors.  I did get a chance to clean up the RF plate that I scored at the local recycle center.

I have been looking around for exhaust ideas and saw Dakota Joe’s RF build in progress.  He originally was looking at using two 4” exhaust pipes and I really liked the idea.   Anyone have thoughts on using two pipes vs one and what I should take into account when I size them?   My original plan with the double pipe was to cut a 10' section of 4” straight exhaust pipe down to get two 42" verticals with a 90 degree elbow into the firebox side of the cook chamber halfway between reverse flow plate and the top giving me a total 1056 cubic inches of vertical exhaust.  Using Dave's method my target for my cc size was 1027 cubic inches (47,704 cubic inch cook chamber x 0.022).

However, I just re-read DJs post and someone pointed out the exhaust stack # is what should be ABOVE the FB, so that would put my pipes at 57.5” vertical to get me the 42” above the CC.  That comes out to 1445 in3 of total exhaust with the 1056 above the cc.   Please let me know what the deal is with double pipe calculations and any recommendations you have.

Thanks,

FB

 

[fatbastard09]

Welding is a lot harder than it looks on Youtube.  After a month of no progress on this project I finally started welding the firebox onto the oil tank.  Having never welded in my life, I practiced quite a bit on scrap the last few weeks and was able to keep two pieces together to the point where I couldn't pry them apart with a breaker bar so I figured I would just start.  I got about 1/3 of the circumference of the 55 gal firebox attached to the oil tank when I ran out of wire.  I bought the $99 Harbor Freight flux core special (I can already see you guys that actually know how to weld cringing) and it only came with a 1# spool.  The tool actually appears to be acceptable for the job, on the high voltage setting with a wire speed of 9 (out of 10) I am getting good penetration on the 1/4" lip of the drum and 3/16" wall of the oil tank and haven't burned through.  I think the biggest issue is my technique (or lack there of).  But, the angle grinder appears to be the novice welder's best friend.  I tested grinding a couple terrible looking welds and it made them look sorta ok, and I know I will be painting over it at some point too.  We'll see what it looks like after I get the drum on. 

My plan is to attached the FB and build the support frame for the unit before I even cut the doors.  There hasn't been any oil in this tank in decades, the main issue inside I can see from the FB/CC cut is surface rust inside.  I am not going to build a fire in it to burn it out rather I plan on hitting it with the big propane torch (the big one they sell to kill weeds) and wire wheeling the inside after I get the hinges welded and doors cut. 

 

[fatbastard09]

My wife pointed out the metal house plant stand in our living room was her uncle's first metal working project. I think she was trying to tell me something...

 

[fatbastard09]

Made progress the last 2 days.

20170415_171849.jpg

• fatbastard09
• Apr 15, 2017

The cheapo welder worked fine, YouTube turned out to be an ok teacher after all...

 

[metalmonkey]

If you are learning welding on you tube I'd check out "welding tips and tricks" channel. I'm a professional welder/fabricator and I still pick up things from Jody's videos.

 

[fatbastard09]

Making progress on this thing.   Since I didn’t burn out the inside, I have been using a wire wheel, grinder, and flapper discs to get the rust and residue out of the cook chamber.   So far, so good.  

04.24.17.jpg

• fatbastard09
• Apr 24, 2017

Next up is to make another door that pulls the top of the tank up.   I wanted to get the bottom rack supports welded in before I cut the top off to help keep the tank square.   I am going with a 6” black stove pipe stack, 48” high with 36” above the cook chamber, I cut the hole for that before I put the rack supports in.

And a thanks to Metal Monkey, the welding tips and tricks site is very helpful!

 

[fatbastard09]

Spent ~20 hours on the top door over the last few days, but its on there and working as intended.   I tried every trick I could find on SMF and Welding Web to get it back into the original shape of the tank (some twice), in the end I feel like I cheated by welding reinforcing rods to keep it in place. I clamped long straight edges across the top of the door on the outside and had to sit inside the CC to do that (now I kinda know what a rack of ribs feels like).  I missed the well documented advice on cutting the door lower until it was too late so I made it harder than it needed to be (the bottom side of the door sprung 4-5 inches), but in the end I have a lot of room to work with on the top rack.

Clamped the door back to its original shape:

20170428_153920.jpg

• fatbastard09
• May 1, 2017

Door back within the original tank shape:

20170429_190133.jpg

• fatbastard09
• May 1, 2017

I started on the RF plate, would have had it installed last night if I hadn't run out of flux core wire.  I have a 1 1/2" drain cut into the plate and through the bottom of the tank (not pictured here).  Once I get the plate in, I have some decisions to make on finishing the plate (more on that later).

 

[fatbastard09]

Was discussing the hassle with the door gaps elsewhere, so I wanted to post a pic of the door braced back on this thread too.  I put a scrap piece of angle across and used the pipe clamp to evenly reshape it.  I got the idea off a welding website, they actually welded large bolts to the top and bottom of the door and put all thread through it but I didn't have anything like that (I am doing this in my driveway with minimal tools and no prior metal working experience).  Also cut out a cardboard guide to shape the tank that I could make sure I got it to the correct shape. After I took this pic, I hit it with the weed torch and spritzed it with cold water on the inside and got the 2-3 inch correction, which ended up not being enough for me.  One other thing I didn't mention before, if you look close at the picture I welded pieces of flat bar on the inside of the edges of the tank so that when I bent the door back down it didn't go too far.

20170428_160116 Braced.jpg

• fatbastard09
• May 2, 2017

 

[fatbastard09]

Here is the plan, I finally got the RF plate welded in place (weather has not been cooperating) and a 1 ½ inch drain pipe per the photo below.  Wait a minute you say, why is the drain sticking out above the plate like that?   Here’s the story:   The RF plate I scored at the recycle center is only 1/8” steel, I didn’t think it would provide enough of a heat sink to maintain steady temps in the CC.   So I got an idea from the RF build cjohnson3006 posted and modified it slightly.   I was able to find a local distributor of castable refractory cement that people use to make homemade pizza ovens.   My plan is to cast the top of the plate with a roughly 1.75” thick pizza oven base.   This stuff (OvenZZ) is designed to retain heat and talking with the sales rep sounded like exactly what I needed.   CJ3006 had used a 5000 psi concrete mix on his RF and said it held up for at least 6 years and helped even out his temps, I am hoping to get similar results.  

20170507_195823 rf plate.jpg

• fatbastard09
• May 8, 2017

To finish this build, this is what I think I have left to do:

• 
  Finished fabricating the racks (I have one frame done so far)
• 
  Finish the supports inside the firebox for the charcoal basket and build the charcoal basket
• 
  Install the top of the firebox air lets (I am going to use 3 sets of 1 1/4 inch pipe installed through the drum with 90 degree elbows inside pointing at the FB/CC opening)
• 
  Install the chimney
• 
  Pour the refractory cement and let cure for 24 hrs, start the first burn to finish the cure of the cement (per manufacturer’s instructions)
• 
  Finish the counterweight for the top door
• 
  Get another seasoning burn going (I am thinking I can do this in conjunction with the next step)
• 
  Prep the outside for painting (wire wheel & flapper discs)
• 
  Paint the pit and frame
• 
  Install the casters
• 
  Drink like a Viking and get some meat on this thing!!

Let me know what you think about the pizza oven RF plate (I have been looking and didn’t see anyone else doing this) and the rest of the plan (what am I forgetting).  Thanks!

 

[fatbastard09]

Question on the charcoal basket, my firebox door is only 9x12 inches (pics above). That's pretty small. I do have the option of making it long though. I haven't found anything on the forums on how to size a basket, I figured I should make it as big as I can as long as it fits through the door? Any feedback would be greatly appreciated.

 

[fatbastard09]

Fired up the rig for 1[sup]st[/sup] time, held temp with very little fuel!   I didn’t even try to maintain a specific temp, was testing the RF plate to see if it would warp before I install the castable refractory base on top (it didn’t) while I installed handles and the counterweight on the top door.   Used ~10 lbs of charcoal to start and double that in seasoned cherry over 5-6 hrs.   It got up to ~300F after an hour and held ~275F with a split or two every 30-45 min.  I haven’t done anything to seal the doors yet and really didn’t do anything to actually mange the fire, so I have to say this exceeded all expectations.  I can't wait to test this out at 225F for 6 hours with racks full of ribs:

20170521_072318 (3).jpg

• fatbastard09
• May 22, 2017

Still on the list:

• 
  Install the pizza oven base on the RF plate
• 
  Another burn to finish curing the base and seasoning
• 
  Fabricate adjustable closure on the upper air inlets
• 
  Sand and Paint
• 
  Put the last weld on the chimney (its just hanging there now, I don't want to put the collar around the pipe against the tank until I paint that area)
• 
  Install casters

 

[sportgd]

Looks like you're making great progress... I unfortunately have no experience and can't add insight but I'm watching!

 

[fatbastard09]

First Smoke Complete!  Finished up the paint job on Friday and Saturday (well, the wife did – I am a terrible painter), one last seasoning burn Saturday night, and then a test cook on Sunday.   Ice cold Iron City, ribs, rib tips, chicken and a 5[sup]th[/sup] Stanley Cup championship for the Penguins!   It really doesn’t get any better than that.   Here are some pics:

Smoker Paint Job 2.jpg

• fatbastard09
• Jun 12, 2017

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• fatbastard09
• Jun 12, 2017

Q View: 

20170611_160539.jpg

• fatbastard09
• Jun 12, 2017

Obviously there were quite a few more rib tips than this pic shows, we were eating them all afternoon along the way and this was all that made it to the table.  I made the sauce in the bottle using tomatoes from garden last summer and Chiavetta's marinade (I'll post the recipe on a different thread, it turned out awesome).

Thoughts on the first smoke:

- I cooked at 225F using charcoal to start, cherry wood for 3 hours, then a little more charcoal and cherry the rest of the way

- I went 3-2-1 on the ribs, put the chicken in for the last 3 hours uncovered

- I didn't want to fill her up in case we ended up with any off tastes due to inadequate seasoning, but we had none of that.  Between grinding down the interior to bare metal and the 3 seasoning burns, no issues at all. 

-  The refractory cement on the reverse flow plate was amazing.  It took less than a minute to get the cook chamber temp back to 225F after opening the doors to service the meat.  I need a few more cooks under my belt but that design feature may be something others might want to look at in the future, I will keep this thread updated on that.

-  We used high temp anodized engine paint (chrome base with blue finish) on the trim and BBQ black on everything else.  This needs another coat of black but it will have to wait.  I waited a couple hours after the painting was done and then used about 10 #s of charcoal and a few sticks to heat it up to cure.  Seemed to work well, the grease from my hands wiped right off during the cook the next day.

-  With only this one cook in, my son and I are doing a cook for 20 people on a camp out this weekend with scouts.  I would have preferred to practice a little more, but this project took a long time (dealing with the weather was the hardest part)

-  For all of you welders out there that have good equipment, a shop to work in, etc I hope you appreciate how good you have it.  Having never welded before and using only the cheap HF welder and burning through 6 angle grinders, I think that would have made a very difficult project a little less frustrating.

-  This was a lot of work but man am I glad I did it.  If you end up reading this post while you are considering building your own rig, I hope seeing the results here push you to build your own.  I hope I have done a good enough job above explaining just how little skill I had going into this thing, so my suggestion to you if you are on the fence is to get a good design and go for it! 

FB