cut open a propane tank

[ch1ch2]

I was reading a post on moving a propane tank.
Got me to thinking. How could I cut it open and make a fire pit out of the end caps.

 

[davesl708]

You must make sure all fumes are cleared from the tank or boom.
By cutting torch or cutting wheel the heat would be enough for ignition.

Cutting wheel would leave a cleaner finish.

 

[Deere Dude]

I wouldn't do that unless I filled it completely with water first, then drain and cut. I would still be worried about it.
I had an empty 55 gallon barrel that had stuff to make fiberglass out of and was flammable., very flammable. It was old and dried when I got around to it,
I had the bung open and was chiseling the top off but that was so slow, so I started cutting it with the welder or a 4-1/2 grinder if I recall. I don't remember which.

All of a sudden I heard a rumble then a very big woof out of the bung hole. I think I soiled myself. Went back to chiseling.

 

[OldGerald]

They make a great fire pit. I have one that has flames cut into the side using a plasma cutter. I often see them advertised around here for better than $300. Should last a lifetime to.

 

[Renze]

I wouldn't do that unless I filled it completely with water first, then drain and cut.

Thats what i do too. But stuff for fiberglass (acetal resin ??) is a different stuff than propane. Water will push out all the propane gas, but resin will not flush clean.

 

[4570Man]

I wouldn't do that unless I filled it completely with water first, then drain and cut. I would still be worried about it. I had an empty 55 gallon barrel that had stuff to make fiberglass out of and was flammable., very flammable. It was old and dried when I got around to it, I had the bung open and was chiseling the top off but that was so slow, so I started cutting it with the welder or a 4-1/2 grinder if I recall. I don't remember which. All of a sudden I heard a rumble then a very big woof out of the bung hole. I think I soiled myself. Went back to chiseling.

Why did you go back to chiseling? All of the vapor had already been burned.

 

[Renze]

Why did you go back to chiseling? All of the vapor had already been burned.

My thoughts too It remembers me of the time i imploded a 1976 vacuum tanker by sucking the suction hose stuck on the bottom of the pit. The old lady couldnt take it and collapsed. a broken off axle U bolt sprung between my fathers boots, he jumped with both feet in the air and yelled "put that thing off, put that thing off" while i couldnt stop laughing whilst saying "now its too late anyway"

 

[Shield Arc]

I've never done it myself. I've read where people wash the tanks out with soap and water. Then plumb the exhaust from a diesel engine into the tank while cutting. A lot of people say never to use the exhaust from a gas engine.

 

[Egon]

Gas engine exhaust is flammable with the right ratio of air.

Fill tank with water & drain several times. If the water can be heated even better. Nitrogen purge while cutting if possible.

If the tank interior is scaly, rusty, or has callcerous deposits on the inside think about different options.

 

[ultrarunner]

At the shop we used nitrogen after ventilating for many hours first...

 

[PILOON]

I have used the blower end of a vacuum cleaner to rid the majority of the fumes and follow up with hot water rinsing. Even then I'd get an occasional small 'woof' of remaining fumes. I usually present , at arms length and facing away, an open flame simply to generate that 'woof'.
That way I know there is no fumes remaining.
I even repaired a car gas tank with that procedure once.

If I had nitrogen I'd use it after the air blowing procedure.

 

[pat32rf]

I made my firepit by using all the propane to boil maple syrup, then pulling ALL the fittings and turned the tank up side down. After it sat for a year like that I marked where I wanted to cut and went at it with a plasma cutter. After I cut it I fashioned a swing away grill out of 1" crusher screen. The hinge point is about 6" OUTBOARD of the tank wall so it swings clear. A piece of tin fits the screen to keep water off of any remaining wood after everything cools.
Next spring I need to cut a nice design of air vent holes in the sides....

Cutting this tank didn't bother me as I frequently cut smaller propane tanks but I also chop up old 200 gallon fuel oil tanks to use the steel for projects. THOSE make me nervous until I know they are clear.....

 

[Jim Timber]

Propane is heavier than air. Remove the valve, flip it upside down (ensuring that gas can escape), come back the next day, put a propane torch to the bung hole and it probably won't "woosh" on ya. Proceed to take plasma, O/A, or cut-off disk to it.

 

[Deere Dude]

Why did you go back to chiseling? All of the vapor had already been burned.

I didn't expect it to whoosh the first time and I heard of tank explosions before and wasn't going to take a chance, again.

But, I did burn the tank out later so there was some dried resin in it yet that remained unburnt, so maybe the vapor shot out and was depleted but the resin would begin vaporizing again. Anyway....

 

[Jim Timber]

They can only explode if they're sealed and able to make pressure. Worst case scenario is you get a little flame thrower off the bung until the fuel is burned off with an LP tank. Other substances like your resin are a different animal.

I'll say it again - drain the tank down, remove the valve, then you can deal with the residual gasses. Always, always, always, always take the valve out first. You can fill it with water if you want, but it's been my experience that gravity does a good job.

A propane torch also helps burn off the mercaptan residue and neutralize the stink. Plasma cutting does wonders as well. I've never found a remedy that'll clear it out better than fire though. Even after years, that dose remains in the tank with the valve off. Just remember that if you're going to use one for an air reservoir (they work great for them btw). Your air will stink for a long time unless you cook that stuff out first.

 

[sixdogs]

Wow, I'm a calculated risk taker but I would rather pay someone that does this to do one for you. No learning curve for you and you get a professional job without the risk. But that's just me and many decades of near death experiences.

 

[Egon]

They can only explode if they're sealed and able to make pressure. Worst case scenario is you get a little flame thrower off the bung until the fuel is burned off with an LP tank. Other substances like your resin are a different animal.

I'll say it again - drain the tank down, remove the valve, then you can deal with the residual gasses. Always, always, always, always take the valve out first. You can fill it with water if you want, but it's been my experience that gravity does a good job.

A propane torch also helps burn off the mercaptan residue and neutralize the stink. Plasma cutting does wonders as well. I've never found a remedy that'll clear it out better than fire though. Even after years, that dose remains in the tank with the valve off. Just remember that if you're going to use one for an air reservoir (they work great for them btw). Your air will stink for a long time unless you cook that stuff out first.

Vapor inside the tank/barrel explodes making the Big Bang. It just needs the proper fuel-air ratio inside. The expansion of these gases is far greater than the opening is able to handle.

Putting a fire under a water filled open tank/barrel works well. A steam hose into the tank/barrel works even better. There are meters that can be used to check the vapour concentrations of the container.

 

[Jim Timber]

I wouldn't do it with a large tank, but a 20# bottle doesn't have enough volume to make much force. Especially not after you let all the vapor drop out.

If the OP is going to do this with a 500 gallon tank - probably want to take some more precautions.

 

[ch1ch2]

Thanks to all!
I got it half done already.
Filled it with water, drilled a small hole in the bottom to let some water out and started cutting on the top with a plasma cutter.
That water stinks.

 

[Threepoint]

Propane is heavier than air. Remove the valve, flip it upside down (ensuring that gas can escape), come back the next day, put a propane torch to the bung hole and it probably won't "woosh" on ya. Proceed to take plasma, O/A, or cut-off disk to it.

Jim, that is one slick stove in your pic. :thumbsup: