Propane tank fire pit

[IHDiesel73L]

I've been wanting a good "bowl" type fire pit for our patio but really heavy ones (ie: won't rust out in one season) are extremely expensive. The other day I was driving down the road and saw a 420lb/120 gallon propane tank laying on its side next to an old garage. I got in touch with the property owner and scored it for $25. I plan on cutting the tank somewhere below the bottom 1/3 so that I have a nice bowl sitting on a pedestal:

First things first before I do anything I'm going to remove the valve and simply let it vent, assuming there's anything in it at all. I've heard of people filling or flushing them with water before welding or cutting but propane vaporizes at -44ｰF so once the tank is depressurized (by removing the valve) and vented to atmospheric pressure it simply turns to a gas and escapes. What's the best way to get a nice clean cut all the way around the body of the tank? Once it's cut open I'm just going to coat it with BBQ paint, put some holes in the bottom for airflow, and maybe a grate to hold the logs/coals off of the bottom.

 

[PILOON]

U can also displace any fumes by blowing air in.
Propane is heavier than air so having the opening propped to face downwards will help.

 

[Rustyiron]

A cut off wheel in a skill saw or big grinder will leave a edge that's easy to "tough up" to a nice safe edge with a sanding disc or a flapper wheel.
You should make one out of each end!

 

[IHDiesel73L]

A cut off wheel in a skill saw or big grinder will leave a edge that's easy to "tough up" to a nice safe edge with a sanding disc or a flapper wheel.
You should make one out of each end!

I've never used one of those cutoff wheels in a circular saw. I wonder if I could set the blade so that it's poking just a 1/16" of an inch or so below the shoe and very slowly go over the line taking off a small amount of metal each time until I break through? The thought of it jamming and exploding if I go too deep is a little scary. As for using both ends, might as well! Maybe I could sell the other one. I need a steel pit for my patio-the only other pit I have is back by our pond which is just a bunch of stone I gathered up from the property.

 

[bcp]

Use the top to cover the bottom when not in use.

Bruce

 

[Rustyiron]

It's easier to "plunge cut" with a skill saw over a grinder. Set the front of the saw's shoe plate down on the tank and slowly plunge the wheel into the tank. The more "blade" you have in the cut (depth) the straighter cut you get, you just need to start out where you want it.

Great idea of bcp on a cover!:thumbsup:

 

[Stimw]

The tank can still be "HOT" even after it is empty for years!!!!!!!
I used to repair semi tankers and fuel/gas tanks and there are tricks if you can't clear them.
We used to run a steam cleaner in the tank for hours then check with meter.
They had to be checked hourly to make sure they did not outgas.

 

[Wilco]

I used the same tank for my fire pit. I marked a cut line with a sharpie, holesawed out a starter hole and cut the tank with a sawzall. took all of about 20-30min. I didn't have air holes initially but found out I needed them after the first fire. The Mercaptan oil in the tank stinks...get it on your clothes or boots and you might as well throw them away. I'd fill it with water at least and dump it before cutting. The tank I used never had gas in it so I skipped the de-gassing.

 

[JPinnell]

I've made quite a few of these (literally 100s) over the years. 1st, just because it stinks does not mean there is still propane in it. 2nd, never trust a tank that you have not personally purged!!

Pull the valve, invert the tank, and leave in the hot sun for a couple weeks to vent the propane and cut down on the stink. You'll need a quality pipe wrench and a cheater bar to pull the valve. Strap the tank to the tractor, etc to keep it from turning, those valves can be TIGHT!!

I like to purge with dry ice (CO2) or hook a hose to the diesel exhaust from your tractor and let it purge a few minutes. Nitrogen and CO2 in the exhaust does the job too and is cheaper. The soapy water method works, but then you have a 100 gal of oily stinky water to dispose of. Older tanks always have some oil in the bottom that was used as a carrier for the mercapitan odorant. Have some oil dry, sawdust, etc to deal with it and do this outside as whatever that mercapitan gets on WILL SMELL FOR WEEKS!!!

I use a plasma to get a nice clean cut and finish with a flap disk to smooth and round the edge. But a sawzall going slow with some cutting oil works too, you'll just need a couple of blades. Abrasive cutting wheel in a grinder always scare me more than the tank itself, too dangerous they bind.

You should be able to get 2 fire bowls and at least 1 if not 2 fire rings from that tank. Sell the extras to offset your time or gift to a neighbor.

 

[adirondackmtnman]

I used an aggregate cone crusher mantle for my fire pit. Even worn past its usable life at the quarry, a two inch thick chunk of manganese makes for one heck of an outdoor living experience!