I do not want to blow my self up

Once you flush the tank with water you can cut it with whatever you want. Torch, abrasive wheel, plasma, jigsaw, it doesn't matter.

The way that I do it is to start with a cut-off wheel in my angle grinder and then finish with a metal cutting blade in my recip-saw. The saw is much faster than the wheel. I don't flush with water - it's a PITA getting water in and out of the valve. And it's not necessary - there's not enough gas in an empty tank to worry about.

Don't use the torch - an oxidizing flame could give a pretty good "whoosh".

To get the smell out, use chlorine bleach

Bob

I'm not sure if this is a good alternative to flushing with water, but what if you pulled a vacuum on the tank, removing gasses from the tank similar to how air and mositure is removed from an air conditioner. IIRC, you can get pretty good vacuum from a hose to your intake manifold, or harbor freight was selling some venturi vacuum pumps for ~$12.99. Or if you know someone that services air conditioning equipment, they might pull a vacuum on your tank for you.

Roger N wrote: I'm not sure if this is a good alternative to flushing with water, but what if you pulled a vacuum on the tank,(clip) ^^^^^^^^^^^ Another alternative would be to drive out the residual gas and air by flushing with a non-combustible substance like the exhaust from an engine. I know of a shop where they weld empty gasoline tanks this way, and that's far more hazardous. This guy hooks a garden hose to the exhaust of a lawnmower engine, and lets it run into the tank for quite a while.

I'm not saying I would try that myself on gasoline, nor do I recommend it to anyone else, but I can't see how you could go wrong doing it on a propane tank.

What about removing the valve? They're not that hard to take off, and even if you have to hammer on the valve a bit to get it to turn, it's brass so it won't spark. Fill with water by putting the hose in, and then upend when finished.

Thank you all for your help I will keep reading and learning Greg

All this time you have spent reading these threads you could have cut the bottom off half a dozen propane bottles, do as Ernie suggested, you want go wrong. Rotty UK

Anyone who cuts into a propane cylinder is clearly barking mad.

Here are our attempts:

Note the finish on the cocktail cabinet. This took an entire afternoon's work to achieve. The original steel is very rough finished and you have to polish it smooth before any sort of oil-bluing will be effective. This took a 40 grit flap wheel, a 40 grit flexi wheel to take the flats out, 80 and 120 grit wheels to polish. Four entire passes over the whole thing - I was knackered afterwards!

Our safety notes: (we accept no responsibility for you killing yourself here - work out your own protocols)

The big _serious_ rules.

Be organised. Full tanks should be clearly marked. and kept away from empty tanks awaiting flushing and cutting.

You can't flush a propane tank ! They have rusty inner surfaces that absorb flammables. If you vent an empty tank, then heat it, you can re-create an explosive atmosphere. It won't be enough to cause damage, but it will scare the crap out of you. Only work on them when they're full of enough water to leave a negligible ullage (air space), or they have at least a foot-square hole in the side.

Don't go near refrigerant tanks. Heating those can create phosgene or dioxins. One is unpleasant in a global scale, the other will kill _you_ dead. It's not worth the risk.

Cutting the tank is easy, because you've already purged it. Dealing with the valve is much more risky.

Our process.

Buy tanks from the local dump. Cheap. They get dumped there, no-one wants them back, no-one wants to dispose of them either. Cheapest steel we can get hold of.

Choose your tank brands. Some have better surface finishes than others, some have more prominent maker's labels.

Burn off the gas. There's often half a tankful left ! Our workshop propane supply is now from these "recycled" tanks - haven't bought our own fill in years.

Burn off the gas. Flare it off with a gas torch until the cylinder is empty.

Consider removing the steel carrying handle, to improve access to the valve. Be careful with this - the cylinder is "live"

Open the valve and leave it outdoors overnight.

Remove the valve. They never unscrew.

Remove the valve. Demolish it by extreme brutality, probably starting at the over-pressure vent. Leave it open at all times. Remember that you're dealing with an unsealed cylinder full of flammables and it may well choose to ignite. There's not enough gas in there to really be a hazard, but you want to be aware of this. I suggest hand tools and sawing the valve off near flush

Using a hosepipe with a narrow pipe on the end, fill the tank with water.

_Then_ add a little detergent to the tank water. Don't add detergent before filling the tank, or you'll have a yard full of foam before the tank is full.

Leave the tank overnight to soak.

Mark your cut lines while the tank is still dry.

Loosely plug the tank's water filling port with a pencil or cork, and turn the tank on its side. Work quickly, before the water drains out - it's better than presure-sealing the bung.

Use the plasma cutter to open the tank. If you have space, knock a nice big vent hole in the side roughly, then stop worrying about the gas. If you're neat though, you can open the tank with a neat first cut, just where you want it.

Plasma cut the tank whilst still full of water. The plasma cutter doesn't mind. The bubbling noises can be a bit odd though. Don't worry if the water drains out - by that time you've got enough venting to avoid gas buildup.

Once the tank is open, wire brush the inside, scrub with detergent and hose it down. Getting the smell out can take weeks. You may like to use the next tank's flare-off to burn the external paint off the cut tank. Paint burning also cures the smell problem.

Good stuff Andy.this post seems to come with everthing you need to get started recycling cylinders apart from the plasma cutter & the guts to try it. thanks

Try to get ones which have been in a fire. Gas is already burnt out. But don't take my word for it! Assume it's still full.

????????? I've never found one yet which won't unscrew. A big hammer to start it, then a socket spanner made from a 1' length of scaffolding. (cut a slot so it fits over the outlet).

-- Big Egg Visit my ebay shop for welding and tools and stuff:

Me either, I tack weld a bar to it about 4 or 5 ft long. No problems. To get gas out of the tank I open the valves and turn them upside down in the sun Let them stay like this for a month. The sun makes them "breath". Expands the air during the day. Sucks it in at night. My tanks usually sit around a month or more before I do anything with them so the gas is well purged by then.

Thanks for the info Dan.

Kruppt

Hmmm ... I'm assuming "less than a quarter turn" is due to the "collar" around the valve? Perhaps, if more than a quarter turn is desirable, one could rig up an offset such that it would clear the collar when turned:

Pipe: ============ } Fitting: ==> } weld or otherwise attach together

-- Big Egg Visit my ebay shop for welding and tools and stuff: