The gas tank in my 50 chevy was full of crap and the original pickup tube was pinched shut. So I cut a square out of the top of it, opened up the pickup tube, and gave it a good cleaning. Now that I'm all done, I need to close up the square. I have your standard 110 MIG and a lot of 18 guage sheetmetal. I was wondering if you guys think it could be done and sealed nicely with a MIG. My pop says it needs to be tig welded, but I don't know anyone with a tig. Keep in mind this is the top of the tank, and it isn't under pressure either. just a standard old tub of metal. What do you guys suggest?
Take it far away from your house and car and get someone to weld it for ya! I'm paranoid about welding on a gas tank. Just aint going to do it. Period. LOL
I've welded several gas tanks. TIG is the recommended method. The reason being is becase when you terminate the arc, the postflow on your TIG will provide your inert shield to prevent that last bubble in your bead, which will cause a leak. But it can be done with a MIG. Flux core is out of the question. Way too sloppy. Use a gas shield and you'll be OK. Your biggest problem will be doing this without blowing yourself up. I HATE welding on gas tanks because the first time I strike the arc I'm waiting for a bomb to go off in my face. Triple rinse the tank as best you can. As soon as you think you've done it enough, do it twice more. fill the tank with water while you are welding it. that will displace most of the vapor, that way instead of a full tank of flammable vapors, you only have a small pocket. Then i try to "burp" the tank. I'll do this by taping some flaming paper or stuff to a long stick and putting it in the tank. That way if that small pocket of vapor will combust, the small explosion will occur at a stick length and not in my lap. If you can flow argon in there while you are welding, do it. Now start welding. It doesn't matter how long the tank has been empty, it is still a dangerous job and one you must respect
I once was gonna braze a tab on a motorcycle tank,washed it out with water several times ,blew it out with air,and you couldn't even smell any fumes.I fired up the torch and figured what the hell I hate surprises so I stood back and passed it over the cap opening.It blew out a blue flame about 10 feet tall.Damn near shit my pants.Anyway be careful welding on it.
That's a false sense of security. there will be less of a chance of something happening. even a small explosion can really fuck you up. think of the violence in a combustion chamber explosion, now picture that uncontained in your lap, scary shit. be careful
We always hooked up the tailpipe to the tank and filled it with exhaust and then welded it. Exhaust won't burn, especially a diesel.
we use a fire ext it disapates the air, not the one that shoots powder...why not solder it............
Full of water MY ASS! all the fumes rise to the top. I once tried it that way. As soon as I put the torch to it KA-BOOM. Knocked two 14 year old kids on our asses. Blew the top of the tank about 6" up and covered use both with water. Go to Shop floor talk and do a search. They say once cleaned, out fill with auto exhaust keeping engine running,then weld it up. Let usknow if it works. Ron
flush it 3 times w/ water. Test it w/ a torch The key to getting leak-tight welds is weld prep. MIG or TIG. Obviously, I prefer TIG - but mig will work as long as you make sure your base material is clean.
Fill it with Argon, or since you're using mig, fill it with a constant supply of C02/Argon mix. Let it purge at 20 cfh for about an hour before you start welding. I did that to a tank that still had a 1/4 tank for gas in it. No problems, no booms. And I brazed it with propane and oxygen!
You might weigh the risk towards the cost of a new tank. I have welded a few. But as I get older and take longer to heal I have became leary of welding gas tanks. Would losing a hand be worth saving a few hundred bucks?
Be carefull when welding a tank full of water, take your time and go slow so it doesn't get to hot. With heat, water boils and creates steam that has to go some where and could cause your take to blow up with scalding hot water.
Agree 100%. WATCHED a Honda 6 cyl bike (CBX?) tank explode and turn the top tube tunnel completely inside out when it was "full" of water and a weld was attempted. If it had of ruptured, the weldor would have been gutted like a fish. The thing with stuff like this is you get away with it MOST times...but you never get to know which time it will turn around and bite you. I've done the "auto exhaust" trick...SCARY as hell and I don't recommend it...filling with an Inert gas sounds reasonable as long as you can guarantee the tank remains full of inert gas AND that all oxygen has been displaced, but the BEST bet is to take it to a TANK shop and have it neutralized properly. Fuel vapors, enclosed spaces and flame are a lethal combination.
It's a flammable vapor, not magic... You can weld it fine - just don't be a moron. Rinse that fucker out (and two more times just to make sure), and test it. If you can stick your oxy torch in the opening and it doest light, it won't when you weld it.
One time about 30 years ago i was operating a large earth mover when I got into a collision with a D8 caterpiller knocked a hole in the fuel tank above the fuel level drove over to where the welder was and run a hose from the exaust into the tank and welded it up with probably 75 gallons of diesel still in the tank. the boss headed for the hills me and the mechanic just laughed at him. PS they laid me off the first chance they got.
The guys who suggested filling the tank with exhaust gas are on the right track. For one the warmth of the exhaust will tend to dry up any remaining fuel residue and filling the space with inert gas is also a good idea. Just make sure that the engine on the other end of the tailpipe is not running dead rich. I have welded lots of tanks this way and have never had an explosion. As someone else noted filling the tank with water will simply displace any existing fumes into what air space is left. Probably less chance of an explosion due to the reduced volume but still a chance of flames. One time I welded a crack on the oil pan (cast aluminum) of a BMW 7 series with the pan on the motor and in the car. Ran a hose (vacuum cleaner size) from the tailpipe of my driver to the oil filler hole in the cam cover and purged the motor for around 15 minutes and then fired up the TIG. Had to bridge the crack as some oil residue was creeping out despite liberal applications of brakeclean but it got the job done and avoided pulling the motor (the only way that the pan would come off). Roo
I had an old timer I buy my bike stuff from tell me a trick they used to do in the 60's when he was building choppers. They would run exhaust fumes into the tank for about 15 minutes. The CO2 vapors chemically neutralize the gas (this is what he said, I didn't proof his chemistry reason). I couldn't argue, so I tried it. I have TIG'd 4 tanks since and no issues. I also rinsed the tanks before too. My personal opinion is that I just can't imagine welding a decent bead on something that thin with water cooling the metal so quickly on the other side. Never done it though so I don't know. If your still nervous, just buy/make a new tank. Why risk it?
...why don't you "glue" the patch on with somethin like "Poxy-Weld" or JB weld, no chance of a bomb goin off and that stuff works great.
I convert old tanks to use intank pumps for EFI conversions, have been doing so for 10+ years, have welded 40+ tanks. All I do is run a garden hose into the tank sitting in the driveway (er, I mean "parts washer") until the "petroleum rainbow" that you can see in the runnoff is gone. Then, plasma, tig and mig to your hearts content.
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