how do YOU prep propane tanks for cutting?

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I have ran across a few opinions here like filling them with water, argon etc. But I would like to know what method each experienced member uses to prep propane tanks for safe cutting and welding.  Its probably something I will be doing in the near future and I would like to be sure and live thru it.Thanks in advance
Reply:Depends on how long the tanks been empty.I made a smoker for a customer, and I saw rust in the bottom of the tank, and I filled with water and made my cuts with a zip disc on a grinder.JMHO.
Reply:Making sure there has been adequate  ventilation you can trickle in nitrogen, eliminating any oxygen and using a grinder with cutting discs. Caution is the name of the game.Sent from my iPhone using Tapatalk
Reply:I have only recycled them, which entailed riddling them with bullet holes so the scrap yard would take them.If its going to be a smoker, fire pit or something like that I would pull the valve stem and burn it, removing all the residual oil and what not from the inside.old Miller spectrum 625 Lincoln SP-135 T, CO2+0.025 wireMiller model 250 and WP-18V torchCraftsman 100amp AC/DC and WP-17V torchCentury 115-004 HF arc stabilizerHome made 4 transformer spot welderHome made alternator welder
Reply:I've been cutting numerous propane tanks lately.   I use both plasma and a cutting torch.  As soon as I remove the valve stem, I fill up the tank with water all the way up until it overflows.  Then drain it and repeat this step three more times.  Propane  is heavier than air, but lighter than water.  The tank will retain the strong odor, but I've managed to get all the gas out.  Then I torch away to cut 'er open.  No problems and I've drained, torched maybe two dozen or more now.  Recently, I made a thread here about a valve removal tool I made for those standard 5 and 20 gallon tanks.  Here is the link. You can see some pics of the latest project too.http://weldingweb.com/vbb/showthread.php...e+removal+toolOne last thing, there should never be "oil" inside of a dedicated "propane tank."Last edited by SuperArc; 12-12-2013 at 09:21 PM.Lincoln Power Mig 216Lincoln AC/DC-225/125Miller  625 X-Treme PlasmaMiller 211 Forney 95FI-A 301HF 91110Victor Journeyman O/PMilwaukee DaytonMakita  Baileigh NRA Life Member
Reply:It's not quite as dangerous as gas tanks, the tanks are meant to vent under fire.  The least safe, but by far the most fun, is to open an inlet and outlet and throw a flare near it.  If you get it perfect, you will get 15 seconds of a jet flame.  If you are ready with a video camera, put a saddle on it.  The propane co near me cuts them all the time because that's the only way recyclers will take them. They just wash them out and go for it.  I'm sure there are plenty of horror stories that will shut me down!  They have a very smelly oil in them which is also somewhat flammable .
Reply:The tank will retain the strong odor, but I've managed to get all the gas out.
Reply:I hook mine up to the car exhaust and take out one of the plugs in the tank. Run that a few minutes and do blackbarts test.  Let the carbon monoxide take all the risk out of it.Arcon Workhorse 300MSPowcon 400SMTPowcon SM400 x 2Powcon SM3001968 SA200 Redface1978 SA250 DieselMiller Super 32P FeederPre 1927 American 14" High Duty LatheK&T Milwaukee 2H Horizontal MillBryan
Reply:Originally Posted by blawlessI hook mine up to the car exhaust and take out one of the plugs in the tank. Run that a few minutes and do blackbarts test.  Let the carbon monoxide take all the risk out of it.
Reply:Originally Posted by difioretinThe tank will retain the strong odor, but I've managed to get all the gas out.
Reply:What is the bottled gas most commonly used to purge the tank?  I'm in the early stages of oldtimers. and I have CRS.Arcon Workhorse 300MSPowcon 400SMTPowcon SM400 x 2Powcon SM3001968 SA200 Redface1978 SA250 DieselMiller Super 32P FeederPre 1927 American 14" High Duty LatheK&T Milwaukee 2H Horizontal MillBryan
Reply:Again, the most common way to purge is with liquid (H20) and not another gas.  Why not go the simple, cheap, safe and effective way if flushing out completely with water?   Has purging is a total waste of money.Lincoln Power Mig 216Lincoln AC/DC-225/125Miller  625 X-Treme PlasmaMiller 211 Forney 95FI-A 301HF 91110Victor Journeyman O/PMilwaukee DaytonMakita  Baileigh NRA Life Member
Reply:I guess I shouldn't say they won't blow.  I have just seen hundreds in wildfires vent,which looks like an explosion to most people.  They will shoot flames 30' or so until they are burn't out.  I do think simply washing them out with detergent and water should be enough.
Reply:So do you empty the water before you start cutting?
Reply:Originally Posted by jamesyarbroughSo do you empty the water before you start cutting?
Reply:I've been wanting to ask the same question. Not to hi-jack but my mom just had her tank (500 gallon)replaced because the date tag is missing and the lp company will not fill it any more. She wants me to ct off each end to make hanging fire pits. I once cut up a 250 gallon diesel tank with a torch. I took it to the car wash and spent several dollars washing it out. I took all plugs out and let it dry and then stuffed it full of news paper and wove a wick and lit it. The first try it blew the news paper out of the opening and the second time it burned up inside the tank. I no longer have the nerve to do this. How thick will the ends of an older 500 gal LP tank be?Last edited by AR. Hillbilly; 12-13-2013 at 05:39 PM.
Reply:I've cut a bunch anywhere from 100 to 1000 gallons. ALWAYS fill with water! I fill it by screwing a hose connection in and let the water run while cutting with the torch. Makes for a nasty cut but you can clean the cuts up after. Once the cut is about half way around you can cut the water off and it's ok. Be sure to have the water take up all the space ( no air pockets ). I cut into an air pocket once on a thousand gal and almost chit my britches!!Miller trailblazer301gLincoln sa200Miller251Miller spectrum 625Victor oxy-acc2002 Chevy duramax 3500 dually 4x4
Reply:Forgot to mention let the water run out of another hole, don't seal it up tight.Miller trailblazer301gLincoln sa200Miller251Miller spectrum 625Victor oxy-acc2002 Chevy duramax 3500 dually 4x4
Reply:Again, use water or an inert gas such as CO2 or Nitrogen, both will completely eliminate any oxygen inside the tank and you only have to trickle them in. Still be very careful regardless of your method. Sent from my iPhone using Tapatalk
Reply:I'm tell'n ya, water flushed in a propane tank is good enough.  The gas is gone once water has pushed it completely out by overflowing.   It's not that scary.Lincoln Power Mig 216Lincoln AC/DC-225/125Miller  625 X-Treme PlasmaMiller 211 Forney 95FI-A 301HF 91110Victor Journeyman O/PMilwaukee DaytonMakita  Baileigh NRA Life Member
Reply:Papasmirf it was CO2 I couldn't think of last post. Never valued my life that much so...... I always piped in car exhaust let it vent out one of the nipples I took a valve out of for a few minutes.Arcon Workhorse 300MSPowcon 400SMTPowcon SM400 x 2Powcon SM3001968 SA200 Redface1978 SA250 DieselMiller Super 32P FeederPre 1927 American 14" High Duty LatheK&T Milwaukee 2H Horizontal MillBryan
Reply:Few years ago, 1st time I ever attempted it, I dumped in about half a box of baking soda then poured in about a pint of vinegar. After foaming stopped, I put a piece of duct tape over the opening, probably overkill, but it worked,  ,  ,  -c-
Reply:Leave the water in the tank. I cut a grill size bottle that was full of water for a week, dumped it out, cut into it and it shot off my work table!
Reply:You could use nitrogen. All you need it to trickle it in and it will dissipate the oxygen. Please be very carefull of any container like thatSent from my iPhone using Tapatalk