i picked up a gas tank from pick and pull and the bastards tehre punctured it...can i weld a piece of sheetmetal over the holes w/out getting blown up? if i were to rinse it out w/ water a lot, or possibly keep it filled while welding, would i be alright? the fumes are very mild and are almost nonexistent if i smell inside the tank...so can i weld it w/out dying?

Since you had to ask this question, I would say no.

I wouldn't want to weld on a used tank unless I was VERY comfortable with the methods used.

I used to solder on gas tanks all the time at the radiator shop i worked at.
Wash the tank out with soapy water several times. Get some heat riser tubing of somethin and fill the tank up with exhaust vapors from a car. Let the vapors fill the tank fo about 5-10 minutes. Just make sure when you do this the sending unit and anything that can be removed is taken off(fuel pump, etc...)

I just heard over last weekend how someone welded on a gas tank - WITH GAS IN IT!

He used CO2 to freeze the gas completely then welded away. :eek:

Not sure if I'd be that brave. But remember a tub a gasoline is explosive but not as explosive as a tub full of gas fumes.

Are you going to re-line the tank? The stuff I use comes with an acid etch to thouroughly clean the tank. After that I don't think I'd have concerns.

get some jb weld if its a small hole,, it works, although kinda cheezy

You might laugh at me for this but before I will weld on one I first wash it out the best I can. Then when I think its clean enough light a rag on fire, taped to long stick and put it in the tank. Only one time did I get a small PUFF. I would much rather find out before I put my face next to it that there is no chance of it blowing. Done atleast 6 tanks this way.

Why would you even want to try?

Aren't gas fumes heavier than air? Either way, can't you wash it out real well, then displace the fumes with air from your compressor? If the fumes are heavier, then hold the tank upside down and start filling with air? Or right side up if lighter? Both of these methods should be able to displace the fumes or at least dilute them enough to not ignite.

Maybe I am just full of crap, who knows....

Peter,

I'll watch the obituraies for your name:eek: :eek: :eek:

I have used the flaming rag test before I welded on motorcycle tanks.
Good luck:nuke:

Course you can always fill it with water, which displaces the gas.

Originally posted by mike
Course you can always fill it with water, which displaces the gas.

Yup, it's called "pressing up"- I've done it on tanks- Not gas tanks though.

rinse with water realy good then do the rag test. I have done this on almost twenty tanks and it works realy well.

you can have the tank boiled-out at a radiator shop. or use a
steam cleaner in it.............. or, just wash it a bunch of times
like these guys are telling you...........

but, another method to void the fumes from inside the tank::

after tank cleaning, and sufficient time to dry inside, place some
dry-ice peices inside the tank for awhile. the dry ice will evaporate slowly, and the dissolving-process of the dry-ice will
flood the tank from the lowest-portion upwards. this will force
the fumes from the tank.

PS: add a ground-wire to EARTH-GROUND prior to doing any
welding on the tank. this is in addition to the ground-wire
on the welder. (if using mig/tig/whatever) if using oxy/acet,
still use an earth-ground wire..........

--Sherpa...


THE COMMENTS CONTAINED HEREIN ARE NOWAY TO BE USED
AS ADVICE. PERFORM YOUR OWN WORK AT YOUR OWN RISK.

Weld the tank full of fuel, and vent the filler neck away from you. Gas vapour ignites, gas doesn't. Weld away, you'll even hear the gas boiling inside the tank as you weld.

The only advice that I see here that's good is the exhaust gas method. I now weld in a chemical palnt on ASME code pressure vessels and piping. The exhaust is carbon monoxide which purges the gas vapors and is and inert gas. We at the plant purge with nitrogen and check with an explosion meter....but when I was training in high school body shop, we had used solder on tanks after purging with the exhaust deal. Good luck and be careful....replacement tanks are easy to come by...a new face isn't!!!

[QUOTE]Originally posted by MR4WD
[B]Weld the tank full of fuel, and vent the filler neck away from you. Gas vapour ignites, gas doesn't. Weld away, you'll even hear the gas boiling inside the tank as you weld. [/B


:eek: :eek: :eek: :eek: :eek: :eek:

I found some Simple instructions for welding with fuel in the tank

http://users.pandora.be/p0p0/youare.swf

Originally posted by MR4WD
Weld the tank full of fuel, and vent the filler neck away from you. Gas vapour ignites, gas doesn't. Weld away, you'll even hear the gas boiling inside the tank as you weld.

Again someone is on crack. :smokin:

So I will pose my question again, WHY TRY? Do it right, why have the risk of killing yourself...loosing parts of you etc etc.

IS IT REALLY WORTH IT? :confused:

Dry ice works, exhaust works.
One problem you run into with just washing it out, the gas will actually permeate the metal of the tank, as you heat it, you drive the gas vapors out of the metal, and :nuke:

I've always used two seperate methods. (wash and water, dry ice, then fill with exhaust, ect) one as a back-up to the other.

The flaming rag test is a good idea, you still have problems with the vapors inside the tank wall, but it's a good back-up.


MR4WD is doing his best to kill someone, heed him at your own risk.

MR4WD, vapors burn, gas doesn't, you got that right.
Now, you are suggesting that we boil gas, creating vapors, with an iginition source inches away??
What happens if a random spark bounces into the fumes???
What if you burn through the metal, right into the vapor pocket you are creating with the arc???
Your stupidity has gone from amusing to dangerous, I can only hope no one is killed or maimed by it.

Hey man, do it your way. I couldn't care less really, I'm stating what I've done. If you end up punching a hole in the tank because you can't weld worth shit then that's your problem, not mine.

Originally posted by MR4WD
If you end up punching a hole in the tank because you can't weld worth shit then that's your problem, not mine.

So, you are willing to give specific advice to a person with unknown welding skills, knowing that it could be dangerous???

I guarentee this: If someone gets hurt following your advice, I WILL MAKE IT YOUR PROBLEM.

Matt

Is that a promise or a threat? Either way it sounds entertaining.

go here: http://www.darwinawards.com

"Darwin awards, given to those who remove themselves from the gene pool in stupid ways"

Well, we know what your goal in life is, now don't we.

Matt

I agree with chark.. In the refinery we use nitrogen to purge any vessels we weld on.. Nitrogen displaces the O2 and prevents combustion..

Originally posted by MR4WD
Is that a promise or a threat? Either way it sounds entertaining.

go here: http://www.darwinawards.com

Diggin your own grave huh?

thanks for the helpful input guys...why do it jason r? well i got the tank cheap, i need a tank asap, this one has a hole in it, i am very confident in my welding, and this seems like an easy way of accomplishing my objective..get the truck running!...im thinking of washing it out many times (at least 5 throughout the day), then using the flaming rag test, then filling it w/ water to displace any leftover fumes then welding it up...if i find another tank to use or have second thughts even after thoroughly cleaning the tank then i'll be forced to buy a fuel cell...and for the haters out there, i started this thread to find out who's done it and the methods used most commonly, im not someone who bought a welder and automatically assumes they can weld, and is anxious to show it off by possibly blowing themselves up...i gues i should have stated that better in the initial post...

Peter,
I did not intend to impune your welding skills. I simply have a great deal of respect for the destructive capacity of gasoline, and have no desire to see anyone else harmed.

Your plan seems sound, I would perhaps use exhaust or CO2, rather than water for the final fill. This is mostly personal preference, any of them will work, I get better welds with a gasous fill, rather than water.

Matt

Peter,

The 12 bolt axle you called me about are gone. Sorry.

If a tank from a 73-8? with dual tanks will work in your application, I have a couple tanks you can have. Email me if you need them, I need to get rid of stuff before I move.

Mike

:eek: :eek:

I've done it. not weled it but brazed it with axcetline/oxygen torch.

got a tank from the wreckers 1/2 full of gas and it had a few small hols on top. So I washed it out a few times using boiling water and TSP soap. then rinced it out a few times. let it vent/dry for 2 days and went to it. not a single problem just welded up like any pice of metal. if your really concernd about it take it outside and run a hose from your tale pipe into the tank and run your engine