Safest way to weld inside a gas tank??????

Never heard of the dry ice method before! I do learn something every day!

 

Safest way ?

Let someone else do it.

 

I ve heard of people running a hose from the exhaust pipe of there car to the tank , But that would only work if you cars emissions were good if not BOOM grenade inspected !!!!!!!!!!!

 

I too worked removing under ground storage tanks and we always used dry ice. Plus we used lots of monitoring equipment to check for oxygen concentrations and lower explosive limit levels before any cutting or removing of the tank. Any inert gas like CO2 or Nitrogen will make it safe to cut or weld.

 

i welded plenty of Motorcycle gas tanks, a few cars too. I just let them completely air out, about a week,2 is better. DO NOT FILL IT WITH WATER it WILL go boom!...

 

Had a friend that needed to "braze up" a small hole in his gas tank at my shop...he did the rinse it out 10 times, then fill it with water bit to push out the explosive fumes deal, left the water in while he brazed up the pinhole, just moved the tank around 'til the hole was on top. It worked fine, until he got impatient and decided to dry out the leftover water with the torch...he was heating the outside of the tank, and looking in at where the last little bit of water was boiling off when she blew-KABOOOMO! Scared the crap outa me! Took off his eyelashes, eyebrows, and about the first 4 inches of his hair...people look really stupid without eyebrows for some reason...he looked like he had bad haircut and a sunburn for a week or so...He was lucky, that time...apparently he closed his eyes just in time...good luck with your project!

EW

 

Cosmo got it right! Back in the 60's my dad showed me how to solder a gas tank the old school way after a profesional welding shop blew up my buddies dirt bike tank. Here are some pics of the old school tools needed, a big copper tipped soldering iron and a torch. The torch is only used to heat the soldering iron. Just remember to keep the torch away from the tank.

 

I'm For the let a shop that does gas tank repairs do it, and at least 4 blocks from where you live!

 

i've got one with with a 3in wide tip, the irion weighs about 15lbs

 

One should wear ear plugs

 

GOT IT DONE!
Drained it, flushed it with water, filled it with soapy water and let sit 2 days.
Positioned the tank so I could weld with the most water in the rest of the tank.
Hooked a dryer vent hose to my diesel truck exhaust, ran the truck for a while.
Tested inside the tank with a burning very long stick. Mig welded 3 small tacks. Done!

Cost of fabbing a swing baffle: $5 bucks
Time spent doing this: 3 hours
Scared? Shitless
Maybe for some things there is Mastercard! haha

Gas tank welding: One more service NOT offered at Kennedy Automotive!

 

-Glad I found this discussion... I used the search feature in order to figure out how to modify my motorcycle tank, and then weld it as safely as possible. I've read lots of welding manuals from the 1930's that emphasize the dangers of welding fuel tanks, and want to tip the scales in my favor.
I am going to use the combination of flushing with water and TSP, dry ice, and the exhaust method. One of the old methods I've read about involved filling the fuel tank with sand...but, I think that is more for something that is being permanently scrapped...not being used again. If I post a follow-up on how mine went, you'll know it went well. If I don't, then... -Tony B

 

It is my experience that gas tanks are hard to blow up. I had an old tank with about 2 gallons of gas in it. Poured a trail of gas to the spout and lit it. When the flame got to the tank it just went woof!. Not to be deterred. Put the tank in the hot sun and sloshed the gas in the tank around. Woof again. Now I am getting frustrated. Get out the welder and put oxygen in the tank. Louder woof. I was a foolish child when I did this and don't recommend it.

 

Let my worthless brother-in-law do it...………..in his garage!!

 

Hmmm, 10 year old thread, op not seen in 8 years...maybe it didn't go well.

 

So you are saying the CO2 will purge the tank of fumes? What happens when you heat the tank up and the pores open up emitting more vapour? Or will the dry ice last long enough to rid the vapour after the tank is heated up?

 

I have patched gas tanks using a soldering iron and silver solder. The Copper soldering iron has no sparks to set off explosion .

 

not sure what you are implying but the gentleman in question died from a serious medical condition unrelated to welding a tank. he fought the fight bravely.

 

Ha, gotta love a good 10 year old explosion thread coming back from the depths.

I hope the guys still in one piece!

 

Sorry to hear the op passed on...too much of that going on amongst us fellow enthusiasts.

It was simply meant as a tongue in cheek comment about another resurection offering advice to a long past thread. No harm meant. I'll head back to my corner.

 

Just a side note. The guys that welding gas tanks that didn't work, are not telling their story

 

Smaller holes are easier to patch with a suitable band-aid metal patch simply soldered over the offending spot. (like the hole worn in my Dodge Dart tank from the pick-up screen rubbing on the tank). I just used a large, electric Vulcan soldering iron and tinned the area around the hole and the mating surface of the patch then pressed real hard whilst heating the whole thing again until the excess solder oozed out.

Every tank I've ever WELDED has been done with oxy/acetylene. I fill the tank with soapy water and tilt it to leave the area to be patched sitting in an air bubble. Any volatile fumes that could burn are contained in such a small pocket that combustion is barely enough to disrupt the flame of the torch.

I've lost track of the tanks I've fixed this way and have never had more than a slight "poof" when I waved the flame over the hole for the first time. The key is to make the air pocket under the area to be welded as small as possible and not have water contacting the back side of where you need to solder..

The larger the air pocket, the larger the explosion. Empty tanks are highly explosive. Full tanks won't explode at all, they'll just burn at the filler neck if it's open.

When I hung out at a salvage yard back in the sixties we used to pull out all the gas tanks and pile all the stripped bodies on top of one car that had the tank still in it (usually a car with a small tank) and fill the tank to the brim and light the filler tube.
If we didn't have any small-tanked vehicles, we'd partially crush a larger tank to reduce the volume, fill it with gas and put it under the bottom vehicle. Once lit, the tank would burn for hours and keep the hulks burning until all the upholstery, wires, hoses and anything else that was flammable was gone then we'd crush them with the iron weight on the crane and load them onto the flatbed to be sold as clean scrap iron.
We got a lot more money for clean scrap than for cars that were simply crushed.
The greenies would have a fit with that today.

 

Drain, air dry, soapy water, slosh around good, drain, then exhaust piped in. Final rinse. Dry. Don't get caught by leaving fuel puddles.
Works fine.

 

Fill with water, dump, Slosh around some ammonia, dump, damn , it actually works

 

If you need to clean out a fuel tank for repair or modification and you can't find a radiator repair shop to "boil it out", do this: If it's got sludge in the bottom, dump in a quart or so of lacquer thinner, then mop up the goo with a rag wired to a stick or a strip of metal. Keep mopping until the goo is gone, then take the tank to a car wash and blast it out with lots of hot soapy water. When you get it home, lay the tank out in the hot sun, the heat will help pull any solvents out of the pores of the metal, to help the process along I hook the vacuum hose to the exhaust side of my shop vac and blow air into the tank until what comes out doesn't smell of gas or oil.
It's pet peeve time: You didn't mention what vehicle the fuel tank fits, and you didn't provide any pictures so we would know what you're dealing with. You did mention it was a "relatively new custom-built" gas tank, but you didn't mention what material the tank is made from. You talk about "epoxy", and "one or two quick spot welds", but the truth is, if you have to ask us how to do it, you can't do it. What you need to do is send the gas tank back to whoever built it, they should have put baffles in the tank to begin with. Best of luck with your project.

 

If you were not aware, don't dump gas in your plumbing, outside yard drains, storm drain inlets/ mh's or sanitary mh's etc- huge risk for explosion. I work in the water sewer business , it happens-https://www.chicagotribune.com/subu...owbrook-explosion-tl-1026-20171020-story.html

 

Not sure why people are wondering how the job went, when the original poster explained his success back in post #41.

I would recommend against cleaning the tank with strong alkali such as caustic soda or TSP as they will remove the terne coating, which protects the steel of the tank from rusting.