Welding on a fuel tank?

Hotrodvw · Posted: Fri Oct 30, 2009 10:43 pm Post subject: Welding on a fuel tank?

What can I do to make a fuel tank safe to weld on??

My plan is to fill it w/ hot water and a touch of dish soap/detergent, aggitate, drain and rinse. Do I need to fill it back up w/ water to help expel any remaining fumes?? I would think that cleaning it would do the trick. Any ideas?
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LeviMan2001 · Posted: Fri Oct 30, 2009 10:56 pm Post subject:

I don't recomend it, but it reminds me of this:

Link

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gkdorman · Posted: Sat Oct 31, 2009 5:18 am Post subject:

I'd just buy a new tank, personally. But if you're serious, the trick the pros use is to fill the gas tank completely, i.e. no room for vapors, as it is the vapors that ignite, not the liquid.
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Hotrodvw · Posted: Sat Oct 31, 2009 7:10 am Post subject:

Well, this is for a '73 F-250 truck fuel tank. We're doing a Retrotek efi conversion, and I need a vent line and a return line. Filling it completely is what I was wondering....not opposed to that. I was just thinking water and electricity together might be another problem. Shocked

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'67 Sunroof
Eric

78x94 with IDA's....oober fun

Horsepower is an addiction........Addictions cost
lots of money!

Hose & Fittings

juki48 · Posted: Sat Oct 31, 2009 7:14 am Post subject:

I've welded tanks before. washed and cleaned with dish soap and water, then I put it on the tailpipe of a running car and let it sit there for a long time and warm up and dry out. then while still on the tailpipe I welded it. if there is only exhaust in there it can't ignite.

Hotrodvw · Posted: Sat Oct 31, 2009 7:22 am Post subject:

Right, the o2 will deplete the oxygen, correct?
_________________
'67 Sunroof
Eric

78x94 with IDA's....oober fun

Horsepower is an addiction........Addictions cost
lots of money!

Hose & Fittings

Type 5 Joe · Posted: Sat Oct 31, 2009 7:26 am Post subject:

I would use generous amounts of Dawn dishwashing soap and the hotest water source you can get.....

Hook up a hose directly to your water heater, turn it up on the hottest setting....Do not let pressure build up in the hose (unless you have a heavy duty restaurant quality hose) it will swell and burst in short order.

Douche it out over and over.... rinse it over and over again with cold water.

Use inert (argon) gas from a welding bottle and completely fill it to purge all oxygen from it... Continue to flow gas through the tank when you are welding.

Be careful.
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Hotrodvw · Posted: Sat Oct 31, 2009 7:28 am Post subject:

The Argon is a good idea....
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'67 Sunroof
Eric

78x94 with IDA's....oober fun

Horsepower is an addiction........Addictions cost
lots of money!

Hose & Fittings

Eaallred · Posted: Sat Oct 31, 2009 7:29 am Post subject:

The tailpipe trick is all you need to do. Put the exhaust of a 'modern' car with a catalytic converter into the tank for about 15 minutes or so. The exhaust is pretty much innert, and is hot, it will dry the tank out and remove all the fumes in short order. Works great, that's what I did when welding fittings onto my stock steel tank.
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Hotrodvw · Posted: Sat Oct 31, 2009 7:30 am Post subject:

But I don't need to have the exhaust flowing while welding it, right? That would suck to be welding and gasping for oxygen! Laughing

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'67 Sunroof
Eric

78x94 with IDA's....oober fun

Horsepower is an addiction........Addictions cost
lots of money!

Hose & Fittings

Type 5 Joe · Posted: Sat Oct 31, 2009 7:37 am Post subject:

It does work, but I would never recommend it as a practice to use....

Using a newer car with a cat is a good Idea, but can you be absolutely sure there is no atomized fuel in the exhaust?

Hate to see you become the victim of a flame-thrower exhaust pipe.

Had an neighbor across the street blow himself up doing this. I don't know if he didn't get the tank clean enough or what. They needed to remove the old guy from the ceiling of his shop with a putty knife. ugly.

Inert gas is the safest method, and gives the best welding results regardless what you are welding... Roll cages, exhaust systems, etc...
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miniman82 · Posted: Sat Oct 31, 2009 8:17 am Post subject:

I've always just washed them out with dish soap, and let them dry. Gonna have to do it again soon, I'm thinking about converting to an in-tank EFI pump.
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Hotrodvw · Posted: Sat Oct 31, 2009 8:20 am Post subject:

I've also considered retro-fitting an in tank pump.
_________________
'67 Sunroof
Eric

78x94 with IDA's....oober fun

Horsepower is an addiction........Addictions cost
lots of money!

Hose & Fittings

sbnova · Posted: Sat Oct 31, 2009 8:33 am Post subject:

If your doing this to a newer Ford fuel tank, you may be able to add lines at the access hole. Alot of tanks have a ~3" diameter "plate" where the sender installs, and sometimes theres room for adding lines to it.

Other than that, Ive welded plenty of used tanks. I always emptied them, washed them out and let them dry before welding. The exhaust trick sounds great- I think I'll use that myself next time as it'll dry the tank out fast.
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Hotrodvw · Posted: Sat Oct 31, 2009 8:34 am Post subject:

I stated above, it's for a '73 F-250 tank
_________________
'67 Sunroof
Eric

78x94 with IDA's....oober fun

Horsepower is an addiction........Addictions cost
lots of money!

Hose & Fittings

Eaallred · Posted: Sat Oct 31, 2009 10:19 am Post subject:

Bruce · Posted: Sat Oct 31, 2009 11:01 pm Post subject:

When I welded on my tank, I just drained it, then stuck the blowing end of the shop vac to the filler hole and let the forced air dry it out. Air doesn't burn, fuel does. With fresh air constantly blowing into it, nothing can burn.
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souper · Samba Member Joined: September 26, 2007 Posts: 67

modern fuel tanks are soldered not welded. If you are trying to weld over a soldered seam you going to have leaks anyway.

6t5 Buggy · Posted: Sun Nov 01, 2009 5:42 am Post subject: Air fuel mixture...

lostinbaja · Posted: Sun Nov 01, 2009 6:01 am Post subject:

Fill it with water and weld it. If there are no fumes or places for fumes it won't ignite.
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