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welding a vehicle with the gas tank still in

05-04-2008, 05:33 PM
I Know when MIG welding you should disconnect the battery......can you still weld with the gas tank in? I'm welding inside the vehicle nowhere near the tank. I was'nt sure if the current flow would have an effect.

05-04-2008, 06:23 PM
Just keep your ground clamp as close as possible to the area you are welding, and keep a fire extinguisher close at hand and you should be all right. It is also a good idea to have the tank full, as there will be less area in the tank for fumes to build up.


10-31-2008, 12:15 AM
I have had a gas tank blow up when I was welding. I was welding in the front end of a 1948 Jeep, the gas tank is under the drivers seat. Lucky, No one was hurt but it destroyed the seat and cracked the windshield. It would have taken me anout an hour or so to remove the tank. I would NEVER NEVER weld when there is the posibility of any explosives in the area!!!

12-16-2008, 04:32 PM

when the tank is empty there's more area to allow fumes to accumulate in the tank and mix with air. Once it hit's the correct 14.7:1 air to gas ratio it'll burst with the slightest of spark. (something like 0.2 Joules or less I think) Welding sometimes creates unseen sparks that travel through odd places on a car.

This includes gas tanks EVEN IF THEY ARE PLASTIC!!! Don't believe me? Ask yourself, Don't you have a fuel pump inside your gas tank? What's it made of? Metal!!! in the form of wires and pump motors which are electrically grounded to the car's chassis.

So my guess with the Jeep is that you had a half full tank, which was metal, and you didn't disconnect the battery (which causes leakage current when you weld, [backwards current when you use certain weld processes])

12-16-2008, 06:26 PM
The gas tank was about 1/4 of a tank. The battery was disconnected. If I had the top on the jeep, or it had been in the garage, it would have had been a total loss! If one of my 4 todlers had been around, it would have been the worst day in my life! Gas is an EXPLOSIVE fuel. If you feel lucky weld away. I would never weld with the tank in again!!!