gas tank weld?

[weaselnoze]

ok so it seems that i wont find a tank anytime soon soo... can i just weld the crack in the tank?  its about 3/8 in long and 1/32 wide.  i know there are vepors in there but cant i just leave it open fora  few days?

[davipu]

yeah you can. it's really thin,  about 0.035"   rinse it with water pretty good then take a oxy fuel torch and carefully stick it in the cap hole. (remove cap first)  worst case senereo because you didn't get all the water out what little gas is left in there is floating on top of the water and not down in the crap pockets.  so it will go wooosh and flame out the top and scare the shaZam! out of you.  don't drop the torch. that should burn most of it out.  then stick the torch back in there and work it around the sides incase you missed something.   BTW TRYING TO LIGHT GAS ON FIRE IS EXTREMELY DANGEROUS CHECK YOUR HEALTH PLAN TO MAKE SURE THEY COVER E-ROOM VISITS.    DO THIS OUTSIDE TO MINIMIZE SHRAPNEL INCASE YOU DIDN'T GET ENOUGH GAS OUT AND IT EXPLODES.  AND HAVE A FRIEND AROUND INCASE YOU NEED TO MAKE A TRIP TO THE HOSPITAL.   but if there isn't enough gas in there to catch fire with a open flame then you can weld on it all day long and it won't explode.

[Faxxxy]

but if there isn't enough gas in there to catch fire with a open flame then you can weld on it all day long and it won't explode.

The empty ones dont catch fire.. They explode...

The only way I know of to weld a gas tank is to fill it as full as possible with water..  Even then its a crap shoot..

Ever see the episode of monster garage where Jesse James would not let a guy weld on a gas tank because he has (and I quote) "Too many friends missing fingers from welding on gas tanks."

[Blueknyt]

yeah, the filling a tank with water lets what little fuel is clinging to metal inside float to the suface thats what goes whoosh when lit.

[Rema1000]

The empty ones dont catch fire.. They explode...

To explode (like, blow-up the whole tank), wouldn't the tank need to be sealed shut?  If the cap is open and the bottom petcock/filter assembly removed, then I would think it may burn, but no ka-boom.

I'd think that you could fill the tank with something which mixes with gasoline, but is not explosive... like diesel.  Then drain the tank.  Acetone could be even better (and cleaner).

As an alternative to welding, couldn't you follow the Kreem instructions, and steam-clean and etch the tank with acid; then fill the crack with JBWeld and sand smooth...  then Kreem the tank as usual?  

But Kreem says it may not adhere to some plastics, so you'd want to test whether it will stick to JBWeld.  An alternative would be to use Caswell tank epoxy (http://www.caswellplating.com/aids/epoxygas.htm).  You can mix up a small bit of epoxy, then thicken it with fumed silica (boat supply store) or graphite powder (hardware store) to form a sort-of runny putty.  It will heat up and get stiffer as it heats. Then force that into the crack from the outside.  About a half-hour later, when the epoxy is "green" (stiff, but a little pliable), then you would want to scrape-down the outside with a bench scraper or razor blade, to try to get it as even to the tank as possible (it will become rock hard and very hard to sand later).  Then, while the epoxy is still "green", mix-up the rest and coat the inside of the tank.  The epoxy inside should seal to your epoxy patch.

Oh, BTW, rather than filling the tank with screws, I've heard that a light chain (such as used to hang houseplants) works too, and is much much easier to fish out of the tank!

[weaselnoze]

grr sounds like way to much work no matter what option i choose.

[GeeP]

First day of welding class at Union Carbide:

Instructor:  "This is a 55 gallon drum.  It last had gas in it 1 year ago."

Instructor:  "This is an arc welder.  It's set to 75 amps."

Instructor:  (Attaches stinger to looong-broom handle)  "This is what happens when you weld on gas tanks."

BOOM!  (55 gallon drum flies through air into nearby field.)

Instructor:  "This is why you only weld on tanks after they have been thoroughly scrubbed out and inerted."

Scrub the hell out of it with cleaner.  Multiple times.  Even better:  Have it steam-cleaned.  Then fill as much as possible with water and inert the rest with a continuous purge of nitrogen.  Don't fill it up fully with water, as the water will take heat away from your weld.  

Your life isn't worth the risk of screwing around.

Edit:  Doesn't matter whether the tank is open or closed, or how may years ago it last had gas in it.  At a minimum it'll "whump", but it could just as easily go off, sending shards of sheetmetal everywhere - including into you.

[weaselnoze]

im going to replace someday but for now im jsut looking for a quick fix.   would using JB weld without kreeming first be ok?

[Roadstergal]

Acetone could be even better (and cleaner).

http://www.bu.edu/es/labsafety/ESMSDSs/MSAcetone.html

Fire:
Flash point: -20C (-4F) CC
Autoignition temperature: 465C (869F)
Flammable limits in air % by volume: lel: 2.5; uel: 12.8
Extremely Flammable Liquid and Vapor! Vapor may cause flash fire.

Explosion:
Above flash point, vapor-air mixtures are explosive within flammable limits noted above. Vapors can
flow along surfaces to distant ignition source and flash back. Contact with strong oxidizers may cause
fire. Sealed containers may rupture when heated. This material may produce a floating fire hazard.
Sensitive to static discharge.

[Rema1000]

OK, so there's a reason why I prefer epoxy to welding.  Must be why I'm still around.

JBWeld is probably OK... but sanding the tank, and etching the inside is important for a good seal.  There is surface rust at the crack, and the crack will eventually corrode, leaking again.

But if you don't care that it may start leaking later (since you're going to throw-out the tank), then I'd say it's worth a shot.   It cures quickly, and you won't be able to sand it much, so it will probably look like !@#$.  I'd recommend the tank epoxy for a better look, since you can mix it to different thicknesses and paint a coat of unthickened epoxy over the thicker stuff in the crack.

[The Buddha]

WTF ... Now I have heard it all ...
Weasel ... Hot water for 10 mins ... In that time have your V-8 powered car or large engined truck started up and maybe even drive it for a few mins ... heck sit the tank in the back and drive around ... Then dump the water, drop a dry towel in it holding one end of it, and soak up water ... then shove the hot exhaust pipe with the car/truck still running into the mouth ... 10-15 mins ... tank should turn warm ... almost as warm as the exhaust pipe ... That should make it absolutely non combustible ...
Cool.
Srinath.

[94suzuki500]

couldnt you actually fill it all the way with gas?  i know a guy who welded his on his truck and just filled it all the way up with gas.  I know it may sound dumb but i know of someone who actually did it.  who knows.

[Blueknyt]

he had to have been BSing you or he used a soldering iron.


JB Weld works fine, my bike was a track bike and its still got the JBW patch on it from its dirtsample from prev owner, ive had it a couple years, no sign of leakage.

[Faxxxy]

couldnt you acutally fill it all the way with gas?  i know a guy who welded his on his truck and just filled it all the way up with gas.  I know it may sound dumb but i know of someone who actually did it.  who knows.

BY "gas" do you mean "gasoline?" or do you mean Nitrogen "gas?"...

[weaselnoze]

in my research i saw the nitrogen thing a few times.   no i dont care what it looks like because it already looks like it had a bad day.  srinath, i'd send it to you to risk it however time wont allow for such thing.   so i think i'll just do it.  i'll sand the area around it and goop it up.  then when all is dry im gonna prime and spray all the exposed metal.  i'll let ya'll know if it works.