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Old 12-16-2012, 09:26 PM   #1
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Default Welding in the trunk

Not sure which category this would be posted under but I want you gays opinion on this. How do you feel about welding in the trunk?

Reason I am asking is I need to finish welding up my rollbar. I do not feel 100% safe being back there and welding around my gas tank. I really don't want to pull it due to I need to be able to move the car around. If I pull the tank that means no rear subframe. No subframe means no rolling the car around.

How do you guys feel on getting the gas out of the tank and blowing the fuel lines out so there is no fuel left, then let the fumes air out with the car outside?
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Old 12-16-2012, 10:36 PM   #2
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Legal disclaimer: I can't attest to the safety of this procedure so Google would be advisable. I do know that Catepiller suggests taking a CO2 fire extinguisher and shooting it into a gas tank and recapping it. They recommend the fire extinguisher because it has a dip tube and you get the snow and not just the gas. The problem is trying to figure out how much co2 is needed to keep the tank from exploding. After you are done welding you can uncap the tank and let the co2 evaporate-FYI CO2 is dry ice.
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Old 12-16-2012, 10:53 PM   #3
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When I did my landing perches in the back by the rear shocks my gas tank was installed. Probably full of gas too, I took the fill and vent hoses off, plugged the holes and welded it up
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Old 12-16-2012, 11:05 PM   #4
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Originally Posted by RyanRaduechel View Post
When I did my landing perches in the back by the rear shocks my gas tank was installed. Probably full of gas too, I took the fill and vent hoses off, plugged the holes and welded it up
That's my thought. I want to completely top the tank off and try to cap off the holes some how. What did you use to plug the tank?
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Old 12-16-2012, 11:35 PM   #5
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Got tig for less splatter, if that's an option.

Have someone look out for stray sparks. Use weld blankets or your buddies leather jacket.
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Old 12-16-2012, 11:40 PM   #6
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I wish we had a tig but only have a mig. If I can find a good way to cap of the gas tank filler/vent holes then I will stuff welding blankets and cover everything well before I attempt to weld it. I know less fuel will cause more vapor so i'd prefer to top the tank, didn't know if letting it air out was an option.
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Old 12-17-2012, 12:28 AM   #7
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Chances are you'll either die from the explosion, or be left in a fairly vegetative/retarded state and your family, unknown to you, will pay thousands per month to keep you alive simply because you have basic vitals signs, which makes you a "human". All the while you'll be laughing uncontrollably at a spec of dust and throwing your food across the table in anger because potato.

I say do it.
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Old 12-17-2012, 12:30 AM   #8
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If you have a gas tank and regulator set up run it to the vent line and just let it trickle in there. I could be wrong but any of the inert gases should help keep the vapors diluted enough.
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Old 12-17-2012, 12:31 AM   #9
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Quote:
Originally Posted by curly View Post
Chances are you'll either die from the explosion, or be left in a fairly vegetative/retarded state and your family, unknown to you, will pay thousands per month to keep you alive simply because you have basic vitals signs, which makes you a "human". All the while you'll be laughing uncontrollably at a spec of dust and throwing your food across the table in anger because potato.

I say do it.
Your words of encouragment are so inspiring
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Old 12-17-2012, 02:12 AM   #10
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Move the car to an open area, cap off the gas tank, throw welding blanket(s) over the tank so stray sparks won't wiggle their way into crevices, and go for it. If you were doing something a lot more intensive like welding in a whole new trunk floor or something it might be another story, but just welding the rear legs of a cage in should be fine.

-Ryan
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Old 12-17-2012, 02:25 AM   #11
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During a cause and origin class a number of years ago we discussed two welders that died while repairing a drain on a gas hauler semi-truck. I forget which common inert gas they didn't fill the tank with, but whatever it was it might be worth your time to google it.
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Old 12-17-2012, 03:24 AM   #12
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Just point a fan at the trunk n weld away.

Te gas tank is behind a bunch of sheetmetal so blech
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Old 12-17-2012, 02:54 PM   #13
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I used rags to cap it, just shoved it down the hole lol surprised I'm not dead.
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Old 12-17-2012, 03:09 PM   #14
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I'm trying to figure out why, if the gas tank is sealed, there would be gas fumes to worry about...
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Old 12-17-2012, 05:20 PM   #15
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Originally Posted by Braineack View Post
I'm trying to figure out why, if the gas tank is sealed, there would be gas fumes to worry about...
I think the issue is heat expansion causing an explosion. I'm pretty sure that's why Catepiller recommended liquid CO2-CO2 displaces the Oxygen.
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Old 12-17-2012, 06:44 PM   #16
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Are you welding the gas tank?
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Old 12-17-2012, 07:29 PM   #17
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Because we worked on large trucks and equipment, we had to weld on fuel tanks from time to time.

If you are just welding in the trunk, you will be perfectly safe.

Still not convinced. Years ago, I went to an outdoor party where some jack *** through a plastic gas can with an open spout into a huge bon fire. We were all scared shitless. The only thing that happened was a small flame was shooting out the spout for at least an hour as the fuel was evaporating. Because the fuel was evaporating, the plastic tank would not even get hot enough to melt or rupture.

As the can approached empty, the flame got a little bigger as the can finally melted. We banned the dipshit from hanging around anymore.
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Old 12-17-2012, 08:27 PM   #18
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Well, whatever you do, make sure you have a gopro behind a plexiglass shield so we find out what happens either way
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Old 12-17-2012, 09:10 PM   #19
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Quote:
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Well, whatever you do, make sure you have a gopro behind a plexiglass shield so we find out what happens either way
Damn! Beat me to it
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Old 12-17-2012, 10:00 PM   #20
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when I did autobody out of high school we replaced quater panels and various other things around the tank all the time, make sure to cover as much of the rubber hoses and suck for the vent with a welding blanket and you'll be fine.

example. 01 S-10's have plastic tanks, I welded in atleast 2-3 cab corners with the bed off and a blanket over the tank, 10-12 spot welded down the back with a mig welder.
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