Anyone cut a propane tank with a plasma?

BabyHuey said:

How did you prep the tank?

I plan to fill it with water and cut it full of water, just wondered if anyone had done that?:idea:

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Just filling it with water isn't going to help you any. If it hasn't been washed and rinsed good and there is gas residue in there then the water will only push the vapors to the top and concentrate them and when the spark hits it will increase the concussion force because of the space being tighter. Another issue I have with trying to use a plasma cutter on propane tanks is that the arc will sometimes stray if there is an irregularity or something in the metal on the inside. I have been cutting along just fine and all of a sudden my kerf runs wild to the right or left of my mark or blows out in a spot only to see after I cut it out that there was a difference in the corrosion on the inside, something adhered to the metal on the inside, or some other issue. A cut off wheel or an oxy-acetylene torch works much better for cutting used propane tanks in my opinion.

Once again, this is just "my opinion" and there may be others that disagree with me and it is all dependent on personal preference. My personal preference is that cut off wheel or oxy torch is better but that does not necessarily make me any more right than someone that would disagree with me and say that a plasma cutter is just fine. BTW, I love plasma cutters and use them a lot in my metal art, but cutting propane tanks just isn't my favorite use for one.

With that about preference being said, I would like to add that the washing and rinsing and repeating to tank is paramount and I would be cautious of just filling one up and cutting. You may could do it 100 times and be fine but just ONE time it blows, and you may not get a "do-over" if you know what I mean. Too late to say, "My bad," when your splattered on the wall of your shop and dripping down the sides.:mrgreen:

Safety first, friend.

that is all.

The bad smell of a propane tank is not from the gas, so do not rely on that to tell you if it still has propane vapors inside of it. It could still smell bad long after the gas has left the tank. Propane companies put an odorant into the propane to alert you when it is in the air.



"Propane in its natural state is odorless. After it is produced, odorant is added to the fuel which allows for its detection. The odorization of propane permits the early detection of leaks before gas concentrations reach hazardous levels. The odorant most commonly used is ethyl mercaptan."

http://tedjohnsonpropane.com/frequently-asked-questions-about-propane/why-does-propane-smell-so-bad/


Propane is very volitile and unstable. if it's left open/exposed to the outside atmosphere it will be gone in matter of seconds. It is so much lighter than air it rockets out into the atmoshere really quickly. Propane vapors are not like gasoline vapors, gasoline vapor's are heavy and will float along a floor and creep all around like water being spilled onto the floor. Propane spilled into a room would rocket up to the ceiling and fill the room from the ceiling down to the floor(like carbon monoxide, they tell you to crawl out of a house that is filled with carbon monoxide) instead of the floor to the ceiling like gasoline. Remember gasoline is a liquid at normal atmospheric pressure and propane is only liquid under extream pressure other wise it's a gas.

Filling completely with water will do the job. It is a gas, therefore leaves no residue.

razrbakcrzy said:

Propane is very volitile and unstable. if it's left open/exposed to the outside atmosphere it will be gone in matter of seconds. It is so much lighter than air it rockets out into the atmoshere really quickly. Propane vapors are not like gasoline vapors, gasoline vapor's are heavy and will float along a floor and creep all around like water being spilled onto the floor. Propane spilled into a room would rocket up to the ceiling and fill the room from the ceiling down to the floor(like carbon monoxide, they tell you to crawl out of a house that is filled with carbon monoxide) instead of the floor to the ceiling like gasoline...

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Sorry but this is incorrect. One cubic foot of propane weighs .1162 lbs. and one cubic foot of air weighs .07655. Dividing .1162 by .07655 equals 1.52. What does this mean? Propane is heavier than air and will seek the lowest space available.

your talking about the liquid state under pressure not the gas state under normal atmospheric pressure...

nmayeux said:

Filling completely with water will do the job. It is a gas, therefore leaves no residue.

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It can leave a residue depending on the type of gas. It can also get trapped in the pore's of the metal. This is why you always "press up" old tanks when you need to cut them. You can either fill them full of water to push all excess gas out, and subsequently filling all the pore's and voids so there isn't enough residual vapor to support combustion, or you can fill the tank with an inert gas that will lower your oxygen level to the point of making the gas inside the tank to lean to support combustion.

I would suggest leaving the tank opend for a couple of weeks. Get a couple of bottles of dawn dish soap and dump in the tank. Fill it with water and let it sit a few days. Drain it, refill with water until it starts to come out clear. Leave the water in it. At this point, you should be safe to cut.

Disclaimer: I assume no legal responsiblity in case of an accident, fire or explosion!!!

I have done 2 propane tanks and the guy that helped me has done 2 as well.
The first one a 120 gal tank I used dawn dish soap (whole bottle) and filled it up with water then drained it twice - then cut it with no problems.
The second tank was a 500 gallon tank - we put dry ice inside about 10 lbs, dumped in some water (a couple gallons) , then plugged the holes to let the carbon dioxide build, then unplugged the tank - what gas that was in there was forced out then we cut the tank.

Right or wrong I don't know but it worked for us.

razrbakcrzy said:

your talking about the liquid state under pressure not the gas state under normal atmospheric pressure...

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Nope. As a liquid propane has an SG of .5 measured against water so liquid propane is lighter than water.

I think you're confusing natural gas which has a specific gravity of .5 to .6 (lighter than air at normal pressure and temperature) and propane which is 1.56 (air is 1.00) thus heavier than air.

Here's a handy reference of specific gravity of gasses

All I know is the stuff will go BOOM! And I be too purty to die so young, SO, I will continue with my overkill routine and ritualistic rinsing and soaking with TSP, draining, rinsing, draining, ONE more TSP and Rinsing and draining and then cutting while it is still wet on the inside. Yep, sounds like over kill but I'd rather be poked fun at than I had be poked with a meat probe to see if I was "done" on the inside.



That is all.

I was trying to talk myself into cutting a tank and it was taking some time to convince myself to do it. I love my family and I was honestly pretty scared to throw the first spark. In the meantime, we ran into a guy in a bar with a Lang 84 he needed to get rid of. I'm happy with the decision.

Slamdunkpro said:

Nope. As a liquid propane has an SG of .5 measured against water so liquid propane is lighter than water.

I think you're confusing natural gas which has a specific gravity of .5 to .6 (lighter than air at normal pressure and temperature) and propane which is 1.56 (air is 1.00) thus heavier than air.

Here's a handy reference of specific gravity of gasses

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I apologize, I stand corrected. I had done just some cursory investigation into the states of propane liquid/gas but did not look up the SG. My inaccuracy is a result of trying to hurry, an often fatal flaw...:shocked::twitch:


To further Slamdunks research, as I now think about it. Where is the sparker located on a gas grill? Below and outboard of the burner so the gas will flow out and down into the spark kernal, Duh!

I have cut two tanks with a plasma, one was a five gallon bbq tank and the other was a 34 gallon D.O.T. Tank. I filled both with dish soap and stapped them in the bed of my truck for a day or two, rinsed and repeated twice, then I stuck an airhose in the tank while cutting, no problems for me. Dont know if this was all the right procedures but................
This is what they became :becky:



Most importatly, Like All have said above BE CAREFUL!