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Old 08-08-2016, 01:37 AM   #1
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cutting/welding gas tanks - techniques...

howdy crazy van cowboy and cowgirl DIYers...

...tell me how you cut and weld your gas tanks without turning into a fireball por favor!

I work as a welder and am pretty handy with a tig, but I've always avoided welding tanks. Now I need to chop and weld two, and I'll be darned if I pay for somebody to do something I can just as easily do myself.

Post up, or PM me please.

Cam.
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Old 08-08-2016, 02:09 AM   #2
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Old 08-08-2016, 09:53 AM   #3
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During the 73 oil embargo someone was despaired for fuel so they chiseled a hole in my fuel tank. The guy that welded it made sure it was empty and then filled it with water. Emptied it and then burned off any residual fumes with a gas torch he held at the open fill tube. There was a pop and flames shooting out the fill tube. Next step was closing the hole. All this was done with the tank out of the vehicle. Definitely exciting.
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Old 08-08-2016, 02:57 PM   #4
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water seems a more solid option. how about precleaning? any info on products/methods used? I've heard of people "popping" tanks after cleaning but I would rather not get snuffed in this process.
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Old 08-08-2016, 11:14 PM   #5
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Empty tank.

Remove sending unit and lid.

Set in sun to "dry out" fuel.

Run exhaust into tank to heat and dry out tank as well as remove O2.

Cut and weld.

No fuel, no 02, no BOOM!
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Old 08-08-2016, 11:17 PM   #6
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What do you want to do exactly? I welded and built several tanks, but it is a huge different if you have a leaking tank or you want to change the size of it.
For closing a hole just fill it with water and let as less space with air in it as possible. Than flame this rest and than start working
To cut it is more difficult as water comes out soon ;-) so flame it several times and be carefull.
You also can use gas to fill it (CO) but i like water more as you see it.
NEVER forget it is a dangerous job, be allways carefull
Once a fuel tank of a motorbike explode while i was wellding it. The airbuble was to big and i know it before that it is dangeous.....but it was the only chance to fix it. After exploding i was laying in one edge of the garage and the tank in the opposite edge. It was an experiance i will never forget
Never forget after flaming it that the fuel is still in the material and tent to go out and built new flamable gas. So it is better to flame it more than once and if you have the chance than wait some hours and change water between flaming.
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Old 08-08-2016, 11:22 PM   #7
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Repeat... we do these all the time. You can't weld with water in it.

Dry it out and replace the 02 with something else...

Quote:
Originally Posted by BajaSportsmobile View Post
Empty tank.

Remove sending unit and lid.

Set in sun to "dry out" fuel.

Run exhaust into tank to heat and dry out tank as well as remove O2.

Cut and weld.

No fuel, no 02, no BOOM!
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Old 08-09-2016, 12:20 AM   #8
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Quote:
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Repeat... we do these all the time. You can't weld with water in it.
Ohhhh damn what did i do the last 30 years?
Of course you have to keep the water away from the welding point. Advantage of water is less room for gas what can explode
54.jpg
here on this german page you see how to do both ways.
BGI 553: Lichtbogenschweißer, 9. Brände und Explosionen durch Lichtbogenschweißen
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Old 08-09-2016, 03:12 AM   #9
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That is the nice thing about getting all the fuel dried out and the O2 displaced - there is no gas to explode.

I can't imagine trying to manipulate an irregularly shaped 35 gallon E-Serries gas tank that you are cutting 4.5 gallons of volume off of one end and then weld a plate on the end of it while it is full of 292 pounds of water.

Someday you can show me how...

For now I will keep my shop dry and not stand in a puddle of water while welding.
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