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Welding on a propane tank


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#1 BucketObolts

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Posted 09 September 2010 - 01:51 PM

I have a empty out dated 5 gallon propane tank. I'd like to convert it into a hippo body but don't have a clue as to how safe this would be. Anyone have any tips on how safe this is or how to make this a safe thing to do?

Scott



What you have to do is to think that each leg, foot, ear or whatever is a separate sculpture and all together make the finish piece.


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#2 AvishaiW

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Posted 09 September 2010 - 02:11 PM

The safest way to assure that there are no flamables left in the tank would be to screw the valve unit out (after you opened it and checked that no gas is flowing out) and fill the tank with water. Than empty the water, dry the tank and you should be able to do whatever you like safe.

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#3 PTsideshow

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Posted 09 September 2010 - 02:39 PM

How long has the valve been off?

Have you had it airing out for a while?

Have you washed it out to remove the sludge that can be in the cylinder?

Are you planning on cutting any openings or just welding on legs, snout, ears etc?

I have had one airing out for a year or so it still smells of the additive that gives the LPG its odor.

I have filled them with water and let them set for a couple of days, then added Dawn commercial cleaner, great oil grease cutting power fill with water 1/2 way and plug the valve opening shake it up and then let it set for a couple hours then turning it over and let it set.
I'm generally not in a hurry to cut or weld on them.

If I got to do it faster, you can air it out you must have the valve removed. wash it out with the oil grease cutting cleaner. Then you can make up a fitting to screw in the cylinder with a hose and valve. Hook it to any inert gas cylinder and add the gas to the propane bottle then when filled you can weld.

If you are going to do a lot of them you can make up a gizmo fitting for exhaust gases to fill the cylinder as you are welding on it.

One other way that is expounded on the net is to fill with water full and plug the holes with a pipe plug or the valve.

A word of caution. Plugging the hole tight, then welding on the tank generates steam. It will get away from you in surprising time. Since water expands into steam about 1,100 to 1,200 times the volume. It would be better to weld it with the open valve hole up and water coming out. I have seen a photo of a pipe threaded in the hole and a hose clamped then run down to the floor keeps the mess down and you aren't welding in a water puddle.

Common sense prevails be smart and be safe.

I will tell you that removing most of the valves is a real pain. The pipe sealant they use is some great stuff. Your local refill shop will remove it for a couple of bucks or so.
You need a special finger wrench that comes down over the valve body. and a strap vise hooked to an I beam to hold the cylinder. My i beam section hooks to the pipe that is in the ground in front of the shop, the the strap a short 3" wide load binder strap. If the safety cage/fence is off if you have a couple of long pipe wrenches (36" and a 48") or two shorter ones with cheaters. You can some times get lucky.
I know somebody that try applying a little torch heat to the valve body. with it closed, there was just a little wiff left in side. It made a nice little pop, but scared the hell out of him! [Beer]

You can pick your way what ever you are comfortable with.

If it has the new valves on it you will need a short hose and tank fitting to vent the tank so the OPD Cylinder Valves doesn't shut the flow off.

A link to everything you never knew you needed to know about propane cylinders
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#4 tommyguns

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Posted 09 September 2010 - 02:40 PM

I just finished making a pig from a 25 pounder. I took the valve off and filled it with soapy water. I let it sit for a couple of days, emptied it, then filled it with water again. When I first filled it I could see gas ripples coming from the opening. I did the initial welding with the tank full of water. I didn't drain it until I had to work on it horizontally.
BE CAREFULL! BE SAFE! We want you to be able to post more of your work.
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#5 BucketObolts

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Posted 09 September 2010 - 04:01 PM

The valve is still on it. It's new to me, I just got it yesterday. So it's still got the fumes and such from over the years. I was wondering how hard the valve would be to remove.
I don't plan on cutting into the vessel. I would remove the ring that serves as a base and the collar/hand grip around the valve. The plan was to add legs,tail,head etc. I'm in no hurry to get blowed up [Beer] so I want to do this right.

After cleaning it out with water/soap/grease remover etc. could you leave the valve off and weld it with no water inside? Having the valve off it shouldn't build pressure if it starts to burn off any gasses? Or is is best to weld with it full of water. Do you leave the valve off when it's full of water?

Any other suggestions for a body? I was thinking milk can, but there are none around here.

BTW nice pig Tommy

Scott



What you have to do is to think that each leg, foot, ear or whatever is a separate sculpture and all together make the finish piece.


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#6 PTsideshow

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Posted 09 September 2010 - 04:23 PM

As Tommy said or as I described in my post about the pipe an elbow short nipple and a section of hose, you can move the pipe around as you need to weld on different parts.

But after washing it out and letting air out a couple of days there shouldn't be a problem you can always try passing a weed burner or propane plumber torch over the opening to see if it shoot flame.

So others suggest suing the valve as a stopper, I have a number of both rubber and cork lab stoppers that I use. I call them self unloading stoppers as they do come out if the pressure inside a cylinder goes up to much.

I understand your hesitation, My first one took some working up to do it.
Just like using the oil tanks for the pits, a little unnerving till you do a couple then its just another process done in steps.

DSCF9924.JPG
If it has the in and outside threads on it it is a new OPD valve you will need to have it hooked up to something to to see if it is empty of propane.
You can look on the side of the safety fence for the markings you will see the empty weight. You can weigh it, and see if it is close.
There can be curd in the bottle as some of the older ones that were used a lot and went from one filling station to another tend to have sludge in them.

Having the valve off it shouldn't build pressure if it starts to burn off any gasses?

With the valve out there shouldn't be any pressure to build up or gasses to go boom.

I was trying to point out that some of the people posting on using the propane tanks or bottles don't always give the facts. or what can happen.

If it is filled with an inert gas any of the TIG or MIG gases or nitrogen there couldn't be an explosion. same as using exhaust inside of fuel tanks to repair them.
[Beer]
glen

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#7 sparkmeister

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Posted 10 September 2010 - 06:08 AM

Cut it while the water is still in it!!
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#8 Dereck Glaser

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Posted 10 September 2010 - 11:35 AM

These can be intimidating but there are so many of them and they offer metalsmiths such a great source of material. We use several here at the school and as we are located in front of an industrial gas supplier, we are fully aware of the precautions. Always remove the valve or have it removed, and this must be done mechanically. Smell is irrelevant to the presence of gas as it is actually in the pores of the metal long after the propane gas is gone, but it does its job of freaking us out, right. Once valves are out you will notice an oily residue which is a by-product of the gas pumping process, as others have stated, cut this with Dawn and hot water, swish and dump. After these the tank should be perfectly safe to cut into, plasma or torch of saw blade. Some gas distributors re-qualify their own tanks and generally have the equipment to remove valves; they will not sell you old disqualified tanks due to liability. There is so much good sheet steel in these not to mention the cool shapes and ready to go vessels,,,,,,,be careful!
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#9 BucketObolts

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Posted 10 September 2010 - 01:17 PM

Well I called my local gas supplier. They don't remove the valves. They only fill the tanks. I am not sure I want to mess with trying to remove it. I am going to give this some thought. I'll look into what else I can come up with.

Thanks for the advise everyone! [Beer]

Scott



What you have to do is to think that each leg, foot, ear or whatever is a separate sculpture and all together make the finish piece.


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#10 Krack

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Posted 10 September 2010 - 08:00 PM

Another idea: if your tank is opened enough to enable you to put some dry ice chunks in it, that would force out or replace the lpg with CO2 as it melts. That would be an additional way of keeping the surprises to a minimum.

#11 AvishaiW

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Posted 10 September 2010 - 08:47 PM

Another alternative to fill the tank with water might be to open the valve all the way and to sink the tank in a water container. I think that it will fill in a couple of hours. You might give it a try.

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#12 PTsideshow

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Posted 11 September 2010 - 03:06 AM

Another alternative to fill the tank with water might be to open the valve all the way and to sink the tank in a water container. I think that it will fill in a couple of hours. You might give it a try.

Not a good idea with the new style OPD valves they have required on all new cylinder in the US.
As there is a float device to prevent overfilling.
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#13 PTsideshow

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Posted 11 September 2010 - 08:28 AM

I am not sure I want to mess with trying to remove it. I am going to give this some thought. I'll look into what else I can come up with.

They say a picture is worth a lot of words.
DSCF0011.JPG
First off the threads are 3/4" NTP so to keep the water mess down you can use any copper or iron pipe fitting into the cylinder.
DSCF0013.JPG
And for those that may not know, a standard garden hose fitting is a 3/4" NTP pipe thread. You can hook a hose and send it where it cause the least problem.
You also can just make up and elbow and another long nipple higher then half the cylinder dia and a little more so the water doesn't come out. When it is on its side.
DSCF0014.JPG
Here is the post/pipe and I beam that with a load strap 2" not 3" that I use a vise for these and oxygen cylinder valve removal.
DSCF0015.JPG
And here is one ready to go.
DSCF9306.JPG
The only caution again is the cylinder must be stone cold empty. The above is a bulk adapter that will hook up a hosed plumbing style torch to a bulk tank. To bleed the propane out, since the OPD valves also have a rupture or excessive flow control in them in case a hose or line breaks.

You can't just open the valve and let it bleed down.Like in the old days where we cracked the valve to blow the crap out of it before hooking it up! Again if any of this make you nervous or uncomfortable, don't do it. As that seems to be when mistakes happen. It needs what is called a metered device at below the flow rate of the valve.
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#14 BucketObolts

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Posted 11 September 2010 - 03:09 PM

[Welcome] Thanks or should I say tanks, Glen. Lots of good info there.

Scott



What you have to do is to think that each leg, foot, ear or whatever is a separate sculpture and all together make the finish piece.


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#15 tommyguns

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Posted 11 September 2010 - 03:14 PM

The valves really aren't that hard to remove. The hardest part is holding the tank while you unscrew it. I clamped mine to a table.
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#16 BucketObolts

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Posted 11 September 2010 - 03:19 PM

The valves really aren't that hard to remove. The hardest part is holding the tank while you unscrew it. I clamped mine to a table.
[Welcome] Guns

What sorta tool did you use on the valve? With the handle ring in the way a pipe wrench don't look like it will fit.

Scott



What you have to do is to think that each leg, foot, ear or whatever is a separate sculpture and all together make the finish piece.


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#17 PTsideshow

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Posted 11 September 2010 - 04:01 PM

With the cylinder empty you can use a cut off wheel to remove the safety fence, handle you then can use the pipe wrench. I have used a large crescent wrench once you break the seal of the pipe dope it comes out pretty easy, but slow as you have to place the wrench at an angle.

Like a lot of things the description of how to do it takes a lot longer than doing it.

The most important Item again is making sure the tank is empty of all pressure, as even 5 to 10 pounds can be an enlightening experience! [Welcome]
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#18 BucketObolts

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Posted 11 September 2010 - 08:21 PM

How do you make sure there is no pressure? I was thinking of putting on the BBQ and see if the BBQ would light. If it does not light does that mean there is no pressure?

Scott



What you have to do is to think that each leg, foot, ear or whatever is a separate sculpture and all together make the finish piece.


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#19 The Welded Horse

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Posted 11 September 2010 - 08:37 PM

i removed the valve on one with the guard still on by taking a good size bar of steel and putting it up against the side of the valve and tapping the bar with a hammer . it worked great to break the seal. just make sure you are hitting on the right side of the valve.

#20 PTsideshow

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Posted 12 September 2010 - 03:23 AM

How do you make sure there is no pressure? I was thinking of putting on the BBQ and see if the BBQ would light. If it does not light does that mean there is no pressure?


If it has the in and outside threads on it it is a new OPD valve you will need to have it hooked up to something to to see if it is empty of propane.
You can look on the side of the safety fence for the markings you will see the empty weight. You can weigh it, and see if it is close.
There can be curd in the bottle as some of the older ones that were used a lot and went from one filling station to another tend to have sludge in them.


The only caution again is the cylinder must be stone cold empty. The above is a bulk adapter(check back to the previous post) that will hook up a hosed plumbing style torch to a bulk tank. To bleed the propane out, since the OPD valves also have a rupture or excessive flow control in them in case a hose or line breaks.

You can't just open the valve and let it bleed down.Like in the old days where we cracked the valve to blow the crap out of it before hooking it up! Again if any of this make you nervous or uncomfortable, don't do it. As that seems to be when mistakes happen. It needs what is called a metered device at below the flow rate of the valve.


By hooking it up and turning the valves on, and letting it open outside for 24 hours or so they will be no hiss or sound from the device it is hooked to. Whether it is a BBQ grille, weed burner torch or any other type propane plumbing style torch. The smell will linger,a lot longer. If the device isn't made to be hooked up to a bulk tank, then you need one of the adapters like pictured in a previous post.

We have been trained for a a lot of years how to respond the smell of propane. It is harder for some people to overcome than others.

On all 4 to 40 pound DOT cylinders in vapor service.

If the valve on the tank isn't a New style OPD valve Then you can just crack open the valve and let the gas out for a couple days.

Propane bottles equipped with overfill prevention valves (OPD) are recognizable by the triangular hand wheel at the top of the valve itself. The hand wheel connecting to the valve stem is tamperproof and is not interchangeable with a cylinder not equipped with the overfill prevention safety mechanism.

OPD valves are designed so that propane will not flow from the service valve unless it is hooked up to a hose end connection. This is the way the OPD cylinder valve was designed. Unattached propane cylinders equipped with OPD valves will not allow gas to flow when the service valve (handwheel) is opened.

DSCF9314.JPG

And finally on the safety fence is the date stamp, and the empty weight of the cylinder. After all of the above you can weigh the cylinder and see how close it is to the stamped weight.
glen

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All the usual and standard disclaimers apply. Do not try this at home, use only as directed, No warranties express or implied, for the intended use or suggested uses, Wear safety glasses, closed course, professionals only




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