Safest way to cut a propane tank for making a smelting pot?

[Rickf1985]

I have several propane tanks that are out of date and the scrap yards will not take tanks. So I plan to make at least one of them into a smelting pot for lead and maybe another into a pot for zinc. I know that just diving right in with a cutting wheel is pretty much suicidal so I plan to use a uni-bit at slow speed with oil for lube to make a large enough hole to be able to fill the tank with water. That way I know there is no gas left in it. What do you guys do?
I already tried removing the valve but that is not happening.

[Minerat]

I cut the top guard off the tank so I can get at the valve. Then take a 12" plumbers wrench with a 4' cheater pipe, strap the tank to a solid fence post and lefty loosy it. They usually break loose, then fill it with water and dawn soap for a couple of days and have at it with a side grinder and cutting wheel.

[country gent]

I remove the valve and fill with dish soap and water about 1/2 full insert a pipe plug and roll around for a few minutes then drain. refill full with soap water and let soak for a few days drain and rinse with water one last time. it is now ready to cut.

To cut pick up a wide roll of wide masking tape decide where you want to cut and make a couple wrinkle free wraps around tank this gives a good straight line to follow. these tanks arnt all that thick. I strap it to a post and use a hacksaw to cut them, it dosnt take long once you break thru the wall. just roll the tank as you cut.

Take it to a propane delivery shop they have the tools and can take the valve out easily.

My last one I made I cut just above the bottom radius about and inch or so then removed the base and cut a 3" wide ring from the remaining welded it on the bottom to make a full dia stand for it. Really stable now.

I lean to the hacksaw over grinder or power tools as there is less chance of a spark if it didnt get completely cleaned out.

Above all be safe wear appropriate PPE, make sure its clean. Another trick is to run compressed air into it while cutting 10-15 psi should keep the possibility of fumes building up way down.

[Cosmic_Charlie]

Timely post. I have an out of date one out back.

[gc45]

Minerat has said it all; we/I an my Son have made quite a few BBQ cookers from propane tanks with narry an issue. We have made three big ones mounted on trailers using 250 gal tanks, several smaller ones using 100 gal tanks..
G

[FLINTNFIRE]

I take off the valve fill with water till it flows out and cut with angle grinder and cutting wheel , smells but is no chance of fire or explosion .

Water will leak out as cutting , no big deal same way I would use a stone cutting blade on skil saw when cutting concrete around old window sills , water keeps the dust down and water keeps it from having any thing to burn.

[baogongmeo]

I trade old tanks in at one of the tank exchange sites. I've asked if they accept old tanks and they've had no problem exchanging them for full ones. Good to have a few extras.
Go to your local hvac repair and see if they have any empty freon tanks you can have. From what I've seen, they are happy to get rid of them.

[georgerkahn]

I've done this but once, and still have 10 each fingers and toes plus two working eyes :)! I did exactly as minerat did, 'cept I used a bigger pipe wrench with tank secured to a telephone pole. My only regret was to see I was/am not too adept at grinding/cutting, and the cut tank really had a jagged/saw-tooth magnified appearance. I then magic marked a black circle to grind much of the high spots down, but it still looks like the opposite place to heaven! Hence, if I did another, I'd NOT grind through at all, but have the tank on its side first -- grinding allllmost but not quite through to make a pretty even grind fully around it -- and then, stand it up to finish the grind through.
BEST!
geo

[Rickf1985]

I trade old tanks in at one of the tank exchange sites. I've asked if they accept old tanks and they've had no problem exchanging them for full ones. Good to have a few extras.
Go to your local hvac repair and see if they have any empty freon tanks you can have. From what I've seen, they are happy to get rid of them.

The pot I am using now I made from a Freon tank, The propane tank is larger in diameter so more lead with less height = lower center of gravity on the burner.

[Budzilla 19]

I used to work in a machine/ welding shop, and we always filled tanks, of any kind, to the top with water, then did welding and cutting on them! It could get exciting sometimes when the water level leaked down a little!! Never did have one pop, but a couple did a “ whoofing “ noise! Freon tanks are safer to cut with a grinder, but all ya got is propane tanks, guess ya gotta make do. Be safe.

[BamaNapper]

I got mine from a friend who took care of purging it for me. With the tank still more than half full, he set up a flame source next to the tank and put a rifle round through the top of the tank from a safe distance. I saw the video and it was indeed impressive. The resulting fireball lit the surrounding grass and the tank sat in the flames for a few minutes. When he showed me the video, the first thing I asked was what he was going to do with the tank. It's now my smelting pot.

Maybe not the safest way to purge a 20-lb cylinder, but definitely one of the more entertaining.

[Winger Ed.]

I've done a couple by opening the valve to vent it, remove the valve a day or so later, fill it with water, drain it out,
then cut what needs to be done with a cut off wheel.

I did a 30 gallon one time by venting it, then left it out in the sun for a couple weeks.
Then filled it with compressed air and vented that a few times, then started cutting...
There was no excitement or that 'whooosh' sound either.

[Oaks&Pines]

Lp is heavier than air so if remove the valve and turn the tank upside down any remaining vapors should exit the tank.

[MrWolf]

I cut the top guard off the tank so I can get at the valve. Then take a 12" plumbers wrench with a 4' cheater pipe, strap the tank to a solid fence post and lefty loosy it. They usually break loose, then fill it with water and dawn soap for a couple of days and have at it with a side grinder and cutting wheel.

I did that but I used a Sawzall that cut it like butter.

[JimB..]

I couldn’t get the valve out, it broke, so I slowly drilled a hole with a hose running on that spot and then filled it with dawn and water. Left it a day then flipped it over in the sun for a day, then ran compressed air through it. Cut with a sawzall.

Lots of ways to mark a line on a cylinder. I usually wrap a strip of paper, but can just tape a marker to any outside corner and spin the tank against it.

[zarrinvz24]

Freon tanks will start becoming rarer and rarer over the next few years. New production systems are all going to a propane based (flammable) refrigerant.

[Winger Ed.]

New production systems are all going to a propane based (flammable) refrigerant.


It didn't get hardly any news coverage- for a couple of reasons, but
years back when the price of R-12 went all stupid, some people were charging car AC systems with propane.

[zarrinvz24]

It works great as a refrigerant, but brazing copper line driers and replacing coils are about to be a thing of the past.

[kevin c]

Is the sludge all that flammable? I know it has the odorant smell but I thought left over propane was the problem. Is filling the tank with water and draining it once enough to eliminate the left over propane and any fire/explosion hazard?

[country gent]

I always wash a tank several time with one being a soak. May nit be needed but it makes me feel safer, same with the air hoe blowing into it. I dont care if its a propane sized tank, 55 gallon drum or larger it gets washed out 3-4 times and a good air flow thru while working on it.

On the job or at home there is no need to "Give Blood" when doing a project. Work safe, a little extra time to make sure isnt a big deal in the end.You can also use the wash soak time to build the frame or other need parts so it really isnt wasted time.

[baogongmeo]

Freon tanks will start becoming rarer and rarer over the next few years. New production systems are all going to a propane based (flammable) refrigerant.

Brilliant!!! What could go wrong???

[country gent]

Older industrial freezers and coolers used Ammonia when they filed the ammonia displaced the oxygen in the building. One failed in this area and half a small city was evacuated for several hours.

[Rickf1985]

Freon will displace the Oxygen but it is not poisonous unless it is introduced to flame at which point you will get flourine gas. Ammonia is poisonous. Very old systems used ammonia. I find it very hard to believe that new systems are going towards propane. That makes no sense at all when flammable refrigerants were outlawed back in the 80's when they started to ban HFC's. My license is still good but I have been out of the refrigeration business for many years now, most of what I did was automotive. Any kind of flammable refrigerant in an automotive system is extremely dangerous due to the high heat under the hood. It was butane back then but same thing, you are above the flash point just from the underhood heat.

[Pablo 5959]

I used a hand held band saw. Had 2 half’s in about 8 minutes.

[Moleman-]

The fridge in our house is a kenmore but was made by LG according to the repair tech that came out to replace the compressor. Seems there is/was a class action lawsuit because the fridge was designed to run off of butane but couldn't pass the UL criteria or something to that effect so they adapted them to run off of R134a which caused premature compressor failure. We opted to have a generic industry standard compressor unit put in v/s the more expensive "it's for sure going to fail again" LG/kenmore unit. Been working fine for 2 years, but I'll never buy another kenmore or lg product.

Now back to the LP tank. There will likely be some clear oily sludge that stinks like the chemical used to give propane a smell. I water purged mine with soapy water several times and still was getting an oil slick mixed in with the rinse water. When the tank was cut apart there was an ounce or two of sticky clear goo at the bottom of the tank that had to be scraped out. Wear rubber gloves or your hands will stink.

[Brassmonkey]

Valve on mine spun off without much trouble, filled with water to displace any vapors that was months ago, I'll get to cutting it and setting the rest up someday.

[GregLaROCHE]

I take off the valve fill with water till it flows out and cut with angle grinder and cutting wheel , smells but is no chance of fire or explosion .

Water will leak out as cutting , no big deal same way I would use a stone cutting blade on skil saw when cutting concrete around old window sills , water keeps the dust down and water keeps it from having any thing to burn.

That’s the way I have done it.

[Ed_Shot]

I removed the valve from the propane tank (not too hard as I remember) filled it with water and let it sit for two days then drained it and cut it just below the weld seam with metal cutting blade in a cheap 4" angle grinder.

[Rickf1985]

Well, at least the one I tried the valve is not coming out due to age and rust and I am not spending a lot of time and energy on something I have no use for afterwards. So it is getting a hole drilled in it and filled that way and then cut with some form of destructive tool. I have about 8-9 tanks out of date so I am not turning them all in, I can't afford to do that at 30.00 a tank! I already have a 100lb. tank that I use to heat my garage.

I will drill a hole the right size for a valve stem and pop one in (I have hundreds left over from my shop) and then I will hook up the air chuck to that for a while to clear out any residual gas and then I will bore it out with the unibit and fill it with water. I can do all of that and expend a tenth of the energy trying to fight that valve off!:grin:

[oley55]

I have about 8-9 tanks out of date so I am not turning them all in,

No doubt there are differences from state to state and there are the really old style with female LH threads, but my local Florida propane company routinely recertifies my old tanks. I just had 4 tanks filled last week and all of them needed to be re-recertified. I have no idea what the fail/recertify criteria is, but they are required to record date codes and what not from the stamped numbers on the handle/guard. I did turn in an old female LH threaded tank, but is was so rusted and pitted on the bottom I didn't think it would be suitable for any use.

[Farmall-130]

Safest way to cut a LP tank is - don’t cut it. Get a 1/4 keg beer tank. They’re stainless steel & the cheap. No risk involved in cutting it.

[Rickf1985]

I just looked through Facebook Marketplace real quick and Beer kegs are running 40-50 bucks. Not exactly cheap. And not all kegs are stainless, some are aluminum.

[G W Wade]

I couldn’t get the valve out, it broke, so I slowly drilled a hole with a hose running on that spot and then filled it with dawn and water. Left it a day then flipped it over in the sun for a day, then ran compressed air through it. Cut with a sawzall.

Lots of ways to mark a line on a cylinder. I usually wrap a strip of paper, but can just tape a marker to any outside corner and spin the tank against it.

Had the same problem with an old propane tank. Took it out to my range at 100 yard and used 22/250 on the valve. Tank was empty. Filled with water and used sawsall on the seam around the middle. Plenty big for my use. GW

[Hdskip]

It is never a bad thing to err on the side of safety in matters like this.

[Rapier]

When I bought this farm, I discovered an old 500 gallon propane tank buried in the ground near where the old house had burned (burglary/arson case). I had to dig the tank loose in the ground with my backhoe and then loaded it up on my equipment trailer for transport to the salvage yard, across the border. I could not figure out a need for a 500 people BarBQ.
Before I got rid of it, I went through the whole business of how to cut. It is pretty much water with soap, flammables permeate the steel, you can not with 100% safely just drill or cut it.

[HogRider666]

Being nervous about cutting any gas tanks I decided to use an old air compressor tank that we had in our workshop. I still took precautions but felt more comfortable.
292079

[JimB..]

Well, at least the one I tried the valve is not coming out due to age and rust and I am not spending a lot of time and energy on something I have no use for afterwards. So it is getting a hole drilled in it and filled that way and then cut with some form of destructive tool. I have about 8-9 tanks out of date so I am not turning them all in, I can't afford to do that at 30.00 a tank! I already have a 100lb. tank that I use to heat my garage.

I will drill a hole the right size for a valve stem and pop one in (I have hundreds left over from my shop) and then I will hook up the air chuck to that for a while to clear out any residual gas and then I will bore it out with the unibit and fill it with water. I can do all of that and expend a tenth of the energy trying to fight that valve off!:grin:

Oh, I just swapped a few really old ones out at the Blue Rhino or whatever. Their propane is high, but you get to use their tank for free and can refill is elsewhere.