Welding on a Propane Tank

[FatFndr]

I have a friend (he has no computer therefore I am asking a question for him) who welded a bracket on a propane tank that he will be using with a propane generator. He used a garden tractor to input its exhaust into the tank until the tank felt warm from the outside. Having purged all the propane out of the tank with the exhaust, he then proceeded to safely and successfully weld on a mounting tab.

Question: The garden tractor had oil blow-by and he feels the inside of the tank now has a slight oil residue on it surface, although he purged the tank with air. What harm, if any, will there be to refilling the tank with propane and using it as is? Will the oil mix with the propane and clog up the jets to the generator? Or will the oil just settle to the bottom of the tank? Any ideas?

Thanks for any input.

 

[Stephenw]

Exhaust gas is not an inert gas. It is a risk to use it to purge a tank that contained something combustible/explosive.

Is your friend an ASME code certified pressure vessel welder?

I say the tank is now scrap metal.

 

[mmb617]

Your friend has balls. No brains though.

 

[walrus]

I have a friend (he has no computer therefore I am asking a question for him) who welded a bracket on a propane tank that he will be using with a propane generator. He used a garden tractor to input its exhaust into the tank until the tank felt warm from the outside. Having purged all the propane out of the tank with the exhaust, he then proceeded to safely and successfully weld on a mounting tab.

Question: The garden tractor had oil blow-by and he feels the inside of the tank now has a slight oil residue on it surface, although he purged the tank with air. What harm, if any, will there be to refilling the tank with propane and using it as is? Will the oil mix with the propane and clog up the jets to the generator? Or will the oil just settle to the bottom of the tank? Any ideas?

Thanks for any input.

There is generally oil in the tank anyway, its what makes that smell so you know if its leaking

 

[reinhardt]

i'm not going to insult anyone here, but i would reccommend getting it pressure tested before filling it and having it near my home! no input on the oil w/ propane problem tho...

 

[sdowney717]

Will the oil mix with the propane

yes, but likely not enough oil to be an issue. Oil is a hydrocarbon as is propane and miscible into each other.
If your familiar with AC compressors, the oil is dissolved in the refrigerant gas and sometimes that gas is propane-butane mixture.
What could be an issue is if the tank shell is compromised.
Even a small propane tank has enough gas to explode with tremendous power.
Also, I think filling a tank with water before welding, cutting, drilling, etc. is better than gases.

 

[WNGER 83]

STOP, STOP, STOP. IF YOU DO NOT KNOW WHAT YOU ARE DOING, YOU MAY KILL YOURSELF.
Be aware that some of the advice given on this site and the Internet in general is wrong. Do not weld on a propane tank, period. The spec's for the propane cylinder are determined without applying the heat from a welding operation, you may have changed the meatallurgic properties of the propane cylinder where you welded on the bracket. The propane clyinder is designed to contain the changing pressure of propane based upon the ambient air temperature, higher in Summer, lower in Winter. Exhaust gas is not inert. Mercapten not oil is added as an odorizer to detect leaks. If you need additional info contact your propane supplier or a propane industry association, do not use or refill this propane cylinder, it should be considered scrap.

 

[NASTYZEN]

OMFG!!!!
I am a professional welder and my advice is also the same as the others on this thread.His tank is now SCRAP.If you like your friend,his family,his neighbors etc.Please make SURE he does not have it filled ever again.In any case the filler person should notice it has been tampered with and not fill it anyway.Once the filler person notices it has been tampered with he is supposed to confiscate the thing so it never gets filled.
If one is going to tamper with a pressure vessel of any kind it should be done by a professional with proper credentials and should be stamped with his approved ID certificate code and then pressure tested by a certified pressure vessel place who also will stamp their code on the tank.

 

[tatra]

chance are it won't be filled anyways..........tampered, altered, welded, etc, tanks are not to be filled.............

 

[tonydanzah]

chance are it won't be filled anyways..........tampered, altered, welded, etc, tanks are not to be filled.............

yeah wont fill an altered tank, but the inert exhause gas idea is pretty good is done with a well running car that has a working cat. If you have ever used a 4 or 5 gas analyzer you could see whats left in the exhaust. Not very much, part of the reason older cars used the egr valves to dump exhaust gas back into the engine at highway speeds to help reburn any remaining particulates and cool exhaust temperature since it is basically inert.

 

[Stephenw]

I've used both a 4 and a 5 gas. Exhaust is mostly nitrogen and CO2, but all it takes is misfire to make an explosive atmosphere.

Exhaust gas should never be considered inert.

 

[tcianci]

He will probably never get anyone to fill that tank since it has been tampered with. So now that I sound like Mr. safety, I can also confess to welding up my own pressure blaster, using a 20 lb propane tank. I subjected it to a crude pressure test before I put it into service. I filled the tank with water and emptied it before any welding was done so any remaining propane was displaced. Although this shade tree engineering may be frowned upon, I think the only difference between my blaster and the cheap Chinese **** that is out there is that if the Chinese blaster failed, there would be someone to sue.

 

[slip knot]

Just out of curiosity. what is the working pressure on a propane tank? Since they quit filling mine due to OPD requirements. I've pulled the valves out of several and use them for remote air tanks and air reservoirs on some air operated equipment.

 

[NASTYZEN]

Also, I think filling a tank with water before welding, cutting, drilling, etc. is better than gases.

Any vessel that has been filled with a combustible liquid or gas has absorbed some of it because believe it or not steel and aluminum are somewhat porous.Therefor your are taking a huge risk regardless of what inert gas you put in it for attempting to weld it.Boom!!
The proper procedure prior to welding is steam-cleaning the thing.Not pressure washing,actual steam.By a professional.Period.
Then you can purge it with ether Argon or Nitrogen witch are the least expensive and available inert gasses around.Yes there is Helium, Krypton and Xenon and another two inert gasses witch I forget the name that are very expensive that can also be used.
Purging means having the gas flow thru the vessel so as to not build up internal pressure so that it will not blow thru the welding fusion puddle.
What I do is use small tube connected to a flow meter that I tape closed to one orifice,preferably on the bottom of the vessel(Argon and Nitrogen are heavier than air)and tape up all other orifices,leaving a small hole on top to let out the air.After purging long enough that only the inert gas remains in the vessel,things (should) be safe for welding.That said,this is still dangerous and should only be performed by a professional!!!!
Now as for putting water in something for preventing it from blowing up, BAD IDEA!!Water has Oxygen and Hydrogen in it,and you can almost never completely fill something oddly shaped thereby leaving a small air pocket=boom!

Now,many moons ago when I was not a professional yet and when I thought I was invincible I foolishly attempted several experiments.

Let me share.Experiment no.1 repairing leaky Honda z-50 gas tank.Mostly filled with water,soldering holes with lead and hot iron=bad idea!No open flame you say,well that thing went clear across the shop propelled by water shooting out of the filler hole by suddenly expanding gasses.I was lucky it went away from me instead of thru me!I did get wet though.
A couple years later a Mini gas tank came my way with a puncture caused by a seized shock absorber.Experiment no.2 using water,this time using Oxy-Acetylene torches = bad idea!!Foom,across the shop again!It did not rupture and became spherical and (unuseable) again the Gods spared me and only wet me instead of killing me .You would think I got smarter......
Experiment no.3 Cracked diesel tank.Aw diesel don't burn easily right?Wrong!!
Filled with water Oxy Ace. torches =bad idea!!Ca foom!!Split big time and really wet this time.Totalled the tank and didn't have a scratch on me somehow.The other thing about water is you could never get proper fusion for the water would keep the metal from reaching proper temperatures or would quench it too quickly and cause crystalline cracks or contamination. Still stupid and intrepid I welded gas tanks with exhaust and Co2 gasses after this with success without blowing myself up somehow.I was very lucky for many times I did get little (fooms )and (pfffss)now and again.
Then I got to thinking,hey I could die doing this.
So then I took a professional welding coarse and learned to weld the appropriate way.Steam cleaning and using inert gasses is the only way and even then,it's taking a chance every time.
I would never ever attempt welding on a Propane tank ever!!!Your friend was lucky this time.

 

[6768rogues]

On a hot day, a propane tank might see 120 lbs., or so I was told by a propane dealer.

 

[chief ben]

I have a friend (he has no computer therefore I am asking a question for him) who welded a bracket on a propane tank that he will be using with a propane generator. He used a garden tractor to input its exhaust into the tank until the tank felt warm from the outside. Having purged all the propane out of the tank with the exhaust, he then proceeded to safely and successfully weld on a mounting tab.

Question: The garden tractor had oil blow-by and he feels the inside of the tank now has a slight oil residue on it surface, although he purged the tank with air. What harm, if any, will there be to refilling the tank with propane and using it as is? Will the oil mix with the propane and clog up the jets to the generator? Or will the oil just settle to the bottom of the tank? Any ideas?

Thanks for any input.

If your Friend is still alive, Stay Away From Him, He Is Danger

 

[nehog]

I have a friend (he has no computer therefore I am asking a question for him) who welded a bracket on a propane tank that he will be using with a propane generator. He used a garden tractor to input its exhaust into the tank until the tank felt warm from the outside.

Does nothing. Exhaust has a lot of oxygen in it, carbon monoxide is flammable as well, as are the waste hydrocarbons from a garden tractor's totally inefficient engine.

Having purged all the propane out of the tank with the exhaust, he then proceeded to safely and successfully weld on a mounting tab.

Safely? No. Successfully? I wonder

Question: The garden tractor had oil blow-by and he feels the inside of the tank now has a slight oil residue on it surface, although he purged the tank with air.

You don't purge a propane tank with air, but with propane. But what is the problem with his 'slight oil residue' on the inside?

What harm, if any, will there be to refilling the tank with propane and using it as is?

If the refiller knows what he is doing, he'll refuse to refill it, so that is safe. If the refiller is not smart enough to just say "it is scrap, buy a new one", then he purges with propane as if it was a new tank, it might be OK, but not safe. If the refiller doesn't purge with propane (doesn't realize the tank was improperly modified, etc.) and just dumps propane in it, the tank is a hazard.

Will the oil mix with the propane and clog up the jets to the generator? Or will the oil just settle to the bottom of the tank? Any ideas?

The oil is such a small part of the problem it is not worth worrying about. He problem is that it is not legal to modify the tank as he did, that how he did the modification is likely a hazard, and that mix of god knows what in the tank now can create a problem as well...

Scrap the tank, buy a new one, and do it right. (That is, don't try to weld a bracket on the tank!)

Thanks for any input.

 

[mad57]

dont scrap it turn it into a pot belly pig and sell the damn thing to recoupe some cash to buy a tank strap. turn it into a pig after safely steam cleaning it of course

 

[rsanter]

He will probably never get anyone to fill that tank since it has been tampered with. So now that I sound like Mr. safety, I can also confess to welding up my own pressure blaster, using a 20 lb propane tank. I subjected it to a crude pressure test before I put it into service. I filled the tank with water and emptied it before any welding was done so any remaining propane was displaced. Although this shade tree engineering may be frowned upon, I think the only difference between my blaster and the cheap Chinese **** that is out there is that if the Chinese blaster failed, there would be someone to sue.

so, whats the PSI in a propane tank when filled with propane verses the PSI you have in it as used as a blaster?
I welded on a tank that I made into a blaster tank. no problems with that.
I do not feel confident about welding on a tank that will be filled with propane

bob

 

[bayou985]

Y'all are nutz never weld on a propane tank...period Ya heard Me??? too purge anything with inert gases always check oxygen level inside with gas moniter

 

[tcianci]

I would be real interested in how after filling a propane tank or any other vessel completely with water, which if you understand your basic high school science, totally displaces any substance in the vessel, there could be any hazard in welding on the tank.

I will agree that without proper testing, no matter what the final application of the tank is, the tank may be unsuitable or downright unsafe. I just don't see any danger in welding on it once all the gas has been displaced out of it.

 

[ripsnortMN]

I welded on a gas tank once after we filled it completely full of water. I was still sh!tting my pants while doing it.

 

[Timpala]

As soon as I saw the title of this thread I knew it would be entertaining and informative.

Good show, can I get some popcorn?

 

[PSYKO_Inc]

Any vessel that has been filled with a combustible liquid or gas has absorbed some of it because believe it or not steel and aluminum are somewhat porous.Therefor your are taking a huge risk regardless of what inert gas you put in it for attempting to weld it.Boom!!

Now as for putting water in something for preventing it from blowing up, BAD IDEA!!Water has Oxygen and Hydrogen in it,and you can almost never completely fill something oddly shaped thereby leaving a small air pocket=boom!

Does nothing. Exhaust has a lot of oxygen in it, carbon monoxide is flammable as well, as are the waste hydrocarbons from a garden tractor's totally inefficient engine.

HOLYSHITUGUYZ! Did you know that there is flammable Oxygen, CO2, water vapor made of Oxygen and Hydrogen, and exhaust from the neighbor's mower in the AIR YOU BREATHE?! ZOMG!

In all seriousness, while there may be a trace amount of propane or other flammable gases in a purged propane tank, chances are there is not enough chemical energy there to even light a cigarette, much less cause an explosion. Also, I don't know if you guys noticed, but a propane tank is assembled by WELDING, so a couple additional welds isn't going to hurt it, so long as the person doing the welding is competent at it. I think you guys are all way overreacting. That said, he may have issues getting the tank filled without having it pressure tested, but I really don't think it's all that unsafe as long as he welded it properly.

 

[sdowney717]

I welded on a gas tank once after we filled it completely full of water. I was still sh!tting my pants while doing it.

if the tank is water filled your ok.
If you doubt it fill a small tank with gas, dump it. fill it up with water overflowing. hit with a torch, there is no burn, nothing.
dont weld on a sealed water tank. water makes steam, steam makes a lot of pressure which can explode a sealed metal tank. (boiler explosion)

If you examine a propane tank, it has during manufacture been welded together. The difference between you doing it and the tank creator is they do this all the time and can properly test the tank, perhaps even xray the welds.
And they have the liability if it fails, but not due to rust.

 

[dellwas]

Um, no, there is no oil in the tank, at least not from propane. It is a chemical that is added, not a hydrocarbon:

Propane's Odor
When produced, propane is colorless and odorless. For safety and detection purposes, a chemical odorant (ethyl mercaptan) is added to propane. The presence of the odorant alerts you of a potential propane gas leak.


http://www.gasco-propane.com/Files/safety.html

There is generally oil in the tank anyway, its what makes that smell so you know if its leaking

 

[eldirector]

When your friend goes to buy a new tank, have him just pick up the proper bracket as well. Kill2 birds with one stone: safe tank and properly mounted!

 

[CraigFL]

A long time ago, I had an expert, weldor friend who used to do all my racing fuel tank repair. He told me all he did was to crack his nitrogen tank valve with a hose into the tank while he welded.

 

[drmoonshine]

I say the oil will do no harm if you can get most of it out and off. As for the new welding how good of a welder is your friend?

 

[Marmaduke]

All I know is everything you said is wrong. Just buy new tank before you blow yourselfs up.

 

[rrangus]

I've used both a 4 and a 5 gas. Exhaust is mostly nitrogen and CO2, but all it takes is misfire to make an explosive atmosphere.

Exhaust gas should never be considered inert.

Carbon monoxide, in the right concentration, is highly explosive.

 

[waltmcq]

Did he get the tank filled? I would think you could weld on a tank and still have it be fine. Did he repaint the tank? I would be nice if you can get some pics.

 

[Junkman]

..........
If you examine a propane tank, it has during manufacture been welded together. The difference between you doing it and the tank creator is they do this all the time and can properly test the tank, perhaps even xray the welds.
And they have the liability if it fails, but not due to rust.

The biggest difference is that they are starting out with raw steel and after the two tank halves have been formed, they weld them together. No propane or no flammable gasses have been injected. Once the welding process is completed, they then pressure test the tank. Once the tank has had propane in it, it is just about impossible to dispose of it. I exchange my old tanks at Wally World for new tanks. The supplier then removes the old fittings, pressure test the tanks and install the new fittings, and stamp a new test date into the tank. I always make sure that they have a clean white paint job on them so there is never a problem with the exchange.

 

[danski0224]

I've always purged my propane tanks with fresh propane before welding on them.

I make sure they are full, too.

 

[PSYKO_Inc]

Well if the tank is full, that means there is no oxygen present, so it can't ignite, right?

 

[danski0224]

Yup... I have to use the flux core wire instead of the O2 shielding gas.

 

[PSYKO_Inc]

Wow, O2 as a shielding gas, you're ********

 

[danski0224]

Can't use that O2 stuff on thin walled propane tanks- the weld puddle is too hot and it burns through.

 

[bcrewcaptain@]

hmm...I have 2 propane tanks in my off road vehicle I have welded brackets/clamps on that have been holding 165 PSI (of air)for a couple years now...a solid tank, with a competent welder, should have no issues with it. As stated above..the tank is welded in production, and those still pass

 

[Tee79]

I work for a company that builds propane tanks, and I'm certified ASME and DOT. I wouldn't worry about the oil getting into it, as much as I would the risk of altering/welding on the tank. The steel itself is pretty thick. But every one of those tanks have to pass through X-Ray, to ensure there's no porosity, slag, undercut, non-fusion ect. There's no way I would fill that tank again, and anyone in there right mind wouldn't do it, as it's been altered. The only thing it's good for now, is maybe a charcoal grill or something!