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jake cleland

removing the valve from a propane tank

27 posts in this topic

i have an empty 100lb propane tank which i plan to make a heat treating forge out of, and i'm wondering how to get the valve out so i can fill it with water to cut it. it seems to be a standard right hand thread, but it's siezed up tight - any pointers?

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i have an empty 100lb propane tank which i plan to make a heat treating forge out of, and i'm wondering how to get the valve out so i can fill it with water to cut it. it seems to be a standard right hand thread, but it's siezed up tight - any pointers?

 

 

Removing the valve is tough, unless you can hold on to the tank. I remove:

 

1) the bleed valve, this valve allows the tank to vent as it is being filled

 

2) the main valve stem

 

A trip to the hardware store to buy some 1/4" copper tubing adapted to a water hose end and you should be ok

 

You have to be sure the tank is 100% full of water before you do anything.

 

Jan

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I've had luck using ratchet type tie down straps or a come-along to clench the tank to a fence post or some other hard to move object.

Matt

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I got a pair of vice grips, after i bleed the tank and filled it with water, and used a hammer to turn the valve off, took about a minute of man hits, which should only be one hit for you Scots.

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I did what Jan said to a 40# tank to make my latest forge out of.

 

i removed the bleed and the valve stem, tipped it upside down (propane is heaver thank air) and let it sit out side to cycle though a week of temp. changes. after that the valve is bronze (non sparking) i used a drill to widen out the hole and filled it with water.

 

good luck and be careful.

 

Joe

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Don't get complacent about it either. I filled mine with soapy water a couple of times (rinsed) thinking that would be enough. Almost blew myself up.

 

After telling that story to a few friends and knifemakers, it was mentioned that new propane tanks are sold with inert gas in them, why they have to purge the tank before first fill up. Much safer way to go than an old tank.

 

Dan

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Don't get complacent about it either. I filled mine with soapy water a couple of times (rinsed) thinking that would be enough. Almost blew myself up.

 

 

 

Dan

 

 

Exactly, I have written in multiple threads that cutting into propane tanks should be left to the experts as its very dangerous. Just because you fill it with water and clean it does not make it safe as it can still hold gas and even solid fuel. I know how to do it but would not bother with it because of safety issues. Making knifes is dangerous enough, I would hate for someone to read this thread and believe they have enough information to cut into a propane tank and end up in the hospital or dead.

 

 

Jake, If you want to use the tank go for it but I would advise you to find someone who has cut open a dozen or more of them to help you do it. You could even ask the local propane shop who they sell old tanks to or who can open them for you, don't underestimate the danger involved.

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When I asked the propane professionals about cutting into one they thought I was nuts. They told me that propane actually gets saturated into the metal of the tank. So even when you think the tank is empty it's not. -Art

Edited by Art Lawrence

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Maybe I am crazy but I've cut about five propane tanks apart and the last two had seized valves. Those two I left the tanks open and upside down for about a week then took a hacksaw and cut the brass valves off, I worked slowly to not build up any heat and had no problems. After I cut the valve off I filled both tanks up with water and used a plasma cutter to cut the tops off. No explosions, no fire. You DO get an awfull lot of the smell and people nearby will freak and think you're crazy but I've done this plenty of times with no trouble.

 

Matt

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I don't plan on cutting any more anytime soon, but I sliced open a couple late last year, with no problems at all. Perhaps I was just lucky, but I opened the valves and let them breathe for a couple weeks, and then it it with the angle grinder with a cutoff wheel. They were truely dead tanks, though, hadn't held gas for quite a while was my impression.

 

Of course the next person to try this will get a bomb in their face, so don't listen to me.

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Bump

 

You have to be sure the tank is 100% full of water before you do anything.

 

 

The angle grinder is plugged into a GFI protected circuit and the water thrown by the zip blade never touches the grinder (a pneumatic tool would be ideal).

 

 

Tank 100% full of water ( a must )

 

GFI protection ( a must )

 

Other safety precautions are a given.

Jan

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thanks for the replies, everyone. I'm not really buying the idea that propane soaks into the metal - if that were the case it would also soak through the metal, and it would make a lousy container... my guess is that the gas collects in all the tiny surface imperfections of the tank. either way, as long as it's completely full of water, residual propane shouldn't be a problem, as there is no way a spark can get to it, and there is no oxygen to combine with...

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i am really confused now.

 

1) tanks that have contained oil must be filled with water otherwise the oil evaporates and blows up. the water fills the tank so there is no room for vapor to mix with oxygen and explode.

 

2) propane tanks contain LPG when the valve is open the tank is left filled with propane vapor which could mix with oxygen and explode.

 

why isnt a propane tank filled with water safe to cut ???????

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I can't imagine a tank full of water containing "solid fuel" and/or exploding. Just because it smells like propane, doesn't mean it is propane. I've had the floor of my shop smell like propane for months and it's a completely open structure, I'm sure the stuff they "flavor" it with is much more long-lasting that the actual gas. But then what do I know..

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The point is messing around with propane tanks is dangerous business. If anyone reads all this and takes it upon themselves to cut into a propane tank do not say you have not been warned because you have.

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just 2 cents

 

the smell is most likely Mercaptan

http://en.wikipedia.org/wiki/Methanethiol

 

i don't think propane has a smell on its own.....

 

mercaptan is also used in the mines as stench gas to alert the miners of a fire underground....... very bad stuff... in that case its strong enough to make you bloooow chunks ... trust me on that..

 

also... propane needs the right air mix to ignite..... fill the tank with water... and no air will mix..... fill the volume of the tank with water and any propane will be displaced.. .. either exhausted out of tank or in solution in the water.......either way, I don't see that conditions for propane igniting being met at all..... just look at the chemistry for it... there is no magic here..

 

and becareful what the Propane guys say at the outlets... there the same guys that won't sell me a simple propane regulator unless i have a licensed fitter come in and work on my forge..... :angry:

 

 

by the way... you can get a very nice liner out of an old water tank... .. or one of those old air tanks

 

Greg

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I have also used the same venting and flooding procedure on a 5# tank without any problems. They are a perfect size for a good working forge. My 60 mile commute to work is far more dangerous and I do that every day.

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I cut the top off a tank a couple of weeks ago. it was an expired tank that still had propane in it. I bled the tank and unscrewed everything I could. I took out the actual valve parts as opposed to getting the whole valve off. I could run a welding rod (cold of course) into the tank itself. and I filled it with water very slowely as the hole is very small using a hose . I then used a gas cutting torch to cut off the top. I actually had to drain off a couple of inches of water so I could cut the steel. never ever ever ever cut into one of these without filling them up with water

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actually :ph34r: .......if you want to see something real dangerous... ... try tempering with oil in pipe.... for swords....

-- have to really watch it to see if it foams.. .... recently i had a real fun time running out of the shop with a 3 foot pipe of 400 deg oil because it all of a sudden started to foam and just wouldn't stop... it caught me off guard cause it never did that before......... i could hear a bubbling sound inside...... and it kept getting bigger...... what the hell....

 

grab the whole stack and ran out the shop with it and put it on the lawn... .......... and it was getting worst.... but how..

 

there was no flame...nothing..

 

so on a hunch i cooled off the base with a water hose.... ( which your not suppose to do with an oil fire but there was no oil fire to be seen ??? unless it was in the tank some how...and underneath the oil ???....... )

 

soon as i cooled the bottom down the foam stopped ...

 

and i was heating it very slowly with an air gun...... doesn't matter anyway....... that shit is outta my shop... i'll go back to tempering in an oven... no need to mess with oils like that.... its just too risky for me...... especially since using an oven is so easy and no risk !!

 

maybe i got spooked too easy... but i'll tell you that 400 deg hot oil foaming out of control out of the pipe got to me... i kept thinking of those oil fires in the middle east .... what a image.... right in the middle of my shop... jeeeeeez

 

G lives another day

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Greg, I can almost guarantee there either was something solid IE a mouse or the like, or some moisture that got trapped in the bottom oil floating on water like it does, when it get's heated it sort of foams like that.

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I have had that happen with my large quench tank and all I can guess also, as Sam mentioned is it's water that oil has absorbed. It's very humid in my neck of the woods. The same oil that I have stored in a sealed 5 ga drum doesn't do that. Any time I quench a hammer in the large container it seems to dry it out a bit.

 

It seems there is excitement around every corner in this wacky craft.

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thanks guys... the water or moisture thing does make sense.... haven't used the oil for tempering in a long while... i usually try to be as safe as i can but that totally grabbed me by surprise..

 

by the way ...sorry i got off topic..

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Propane is pretty much odorless . The smell is onion oil , added for safety . The onion oil ( and the smell ) can hang around for a long time . For the far northerners , when the temps drop to a certain point , propane will no longer turn to gas but will remain liquid , even if poured out of the container . it can even soak into the ground only to transform into a flammable / explosive gas when temps come up . This is a good fuel , but it will not pass up a chance to take you out .

Careful all .

 

Kenny

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thanks guys... the water or moisture thing does make sense.... haven't used the oil for tempering in a long while... i usually try to be as safe as i can but that totally grabbed me by surprise..

 

by the way ...sorry i got off topic..

 

Greg,

 

Thank you for sharing that scary experience with us, very very valuable (every near miss is a valuable story). Moisture is a likely cause no doubt. I am wondering if the oil was a commercial heat treating oil or a vegetable oil of some kind...is it possible the quenching breaks down some of the oil into more volatile components. When seeing a fast food place roof vent, we now know that they are flashing off something. Would mechanical agition help (bringing up "bottom oil" to the top? What about a smaller tube running from the bottom (outside the main body) to near the top...and only heating this tube.

 

The day before you posted this , I had just located a SS container with lid for oil quenching (not tempering)....now I am certain to keep it on the cool side, thank you.

 

Jan

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