Topic: I'm trying to not blow myself up!

[jgger]

Like the title says, I don't want to blow myself up. So I  need some advice on welding or using a torch on a bent gas tank. I have a leaking tank on my FJR and it really is past gone, so I found a bent one from a part out. There is no liquid at all in the tank and you have to put your nose practically inside to even get a faint wiff of stale gas.

What I want to do is tack welding rod to the dents and heat the area around the dent and pull the metal close to it's original shape. Ever since I was a kid I have heard horror stories about people welding on gas tanks or cans. If I can get the metal I think I can end up with a presentable tank when it's done.

So what steps or precautions do I need to take to introduce a flame to the outside without creating a bomb?

[Don R]

 I've had good luck with the hot glue dent puller, the cheapie kit I got was a little weak so I used 5/16" brass toilet bowl bolts and pieces of wood I modified to bridge over the high points.
 If it comes to welding, I rinse with alcohol to get the gas out and then water to get the alcohol out, dry it then fill it with argon or C02 from my mig/tig bottles. Argon is inert, heavier than air and will fill a tank like invisible water.
 I saw a guy cut up a gas station tank once, he used the exhaust from his truck to displace the oxygen. It ran for hours before he cut it. (no choke please)
 I welded a flanged valve on a train car sized maap gas tank once. It sat for a week with the ports open but I still managed to bannnng a check valve open and closed when the arc crossed a gap in the root weld left from the day before. Needed new shorts.

[Alan F.]

I'm not a welder but it's my understanding that the fuel vapor in combination with ambient air is what produces the combustible mixture. I'd flush your tank out with alcohol or other solvents that would evaporate, water would probably do but would encourage rust & who wants that.

I think the safest route would be to drain and flush the tank, warm it to encourage evaporation, then fill the tank with an inert, nonflammable gas before proceeding. I'm not sure I'd put the gas cap back on, maybe some painters tape though.

Would welding shield gas do the trick? That's argon right?

[jgger]

Both you guys mentioned alcohol,  would that be rubbing alcohol? This tank is for a fuel injected bike and the fuel pump has been removed at least 3 weeks ago or longer.. There is about a 3 inch hole where it mounts so this thing has been aired out pretty good, if I wanted to use a non-flammable gas it might be hard to contain it in the tank.

Is the absence of fuel smell reliable to consider it safe? If it were to flash and damage the tank it's not a big deal, I only paid $30 for the tank. I just don't want to lose any body parts in the deal.

I have used the dent puller, the problem is the hot glue isn't holding very good.

[BomberMann650]

Taking the cap and fuel pump out kinda negates the whole "it go boom!"

[jgger]

Thanks guys for the advice I may just roll the dice in this one. If it doesn't go well for me please don't bad mouth me when I'm gone!🙈🙉🙊

[calj737]

You won’t be able to weld anything to that tank until you remove the paint in the damaged areas. A heavy rinse with soapy water is more than adequate since you are only tacking to the outside of the tank.

I doubt pulling those dents will yield the best results. Likely you’ll need to push them from inside via Paintless Dent Repair methods.

[jgger]

Thanks Call, the plan is for a strip and repaint to match the rest of the body pieces, so the paint is comming off anyway. So far I have pulled with a dent puller and used a wood dolly to smack from the inside, the large fuel pump hole gives pretty good access. I will peck away at this because I like the challenge.

If this turns out good I will post pictures, if not then I'll go quietly off into the sunset!

[Don R]

 Don't close it up, I've seen guys reach around a corner with a propane torch and burn off the fumes from an open cap. I don't recommend that but closing it up tight makes it a potential bomb.

  Rubbing alcohol works as good as methanol. I use it because in my opinion, alcohol mixes with the gas to remove it and then water mixes with alcohol to remove it. I've used a shop vac outlet and a leaf blower to dry and blow sediment from the inside of the tank.