motorcycle gas tank welding -advice needed

I have an old gas tank off of a motorcycle that needs a mounting tab tacked on to it. When I emptied the tank, the gas was real old and smelled like varnish so i flushed the tank with acetone (rusty in there), then rinsed it out with soapy water several times. I dont think it would explode because of the age of the fuel that was in it and it was thoroughly rinsed but i'm not a big fan of blowing my fingers off my body so i'm a bit relunctant to mig this thing. A friend suggested to go outside with the cap off and stick a propane torch in the opening and see if it flashes. If it doesn't, it most likely wont explode. Any comments before I muster up enough nerve to tack this tank.

thanks in advance, walt

Reply to
wallster
Loading thread data ...

Walt,

You have taken some good steps to get rid of most of the fumes. Buy a nice chunk of dry ice and put it in the tank and LIGHTLY cap it. (Saran Wrap the gas cap flange). This will keep the CO2 in the tank but let any pressure escape if necessary.

Done this on car gas tanks and no problems.

I don't thing trying to make it explode by putting a torch in it is a good idea.

Bart D. Hull snipped-for-privacy@inficad.com Tempe, Arizona

Check

formatting link
for my Subaru Engine Conversion Check
formatting link
Tango II I'm building.

Remove -nospam to reply via email.

wallster wrote:

Reply to
Bart D. Hull

One traditional method is to pipe car exhaust fumes into the tank to flush out anything combustible and to displace all the air so there's no oxygen. Exhaust gas, having been burnt once is pretty much inert so any remaining petrol vapour won't ignite anyway. You need to keep the exhaust running while you weld of course.

Reply to
Dave Baker

Have you ever personally done this, Dave?

Jim

Reply to
jim rozen

all done fellas! I purged the tank with argon from my tig and tacked it with the mig... no boom. thanks, walt

Reply to
wallster

Just fill the tank up with water. Close the cap and vent tube. Turn the tank over so that the area that you are going to weld is located at the small air space left in the tank. I have done this with Oxy-acetylene and occasionally I would get a little burp at the crack or opening I was repairing. There wasn't enough space for any gas residue to have any power. Randy

Reply to
Randy Zimmerman

I did the same thing. I got a hole in my tank from something that got kicked up off the road. I filled the tank with water and as much as I could leaving only a small air pocket. I was going to braze weld it shut with my propane & oxy torches. I had at least 90 % full of water. When I put the torch to it the tank still had enough vapor in it to cause it to give a big burp. Water sprayed me all over from the fill hose. It scared the snot out of me! I wasn't sure if it was the water from the tank, or if I pissed my pants!

Randy Hansen SC Glass Tech Scam Diego, Comi-fornia

Reply to
Randy H.

Nope, as I don't weld, or at least only in extremis. I've heard it mentioned a number of times though by racing people having to do emergency repairs at the trackside.

Reply to
Dave Baker

I once had to weld a hole in my car gas tank .So i took the tank out and filled it with water I emptyed it and did this 3 times . But i still smelled a slight gas smell .So i rolled up a news paper about 3 foot long put one end in the tank and lighted the other end and got away from it.To my suprise there was a loud bang .It expanded the tank alittle but a mashed it back in and fixed the hole.

Reply to
TLKALLAM8

hehehehe.... where's a camera when ya need one! walt

Reply to
wallster

I have done quite a few with co2 or argon, and no embarrasing burp either. Do yourself a favor while it's cleaned out, and line it with Red-Kote (my favorite), Kreem, or some other "fuel tank sloshing compound".

Reply to
Paul Calman

wallster wrote in article ...

I, for one, would be interested in understanding why a gasoline vapor explosion caused by a propane torch is, somehow, of lesser energy - thus safer - than a gasoline vapor explosion caused by any other source of ignition......

Reply to
Bob Paulin

On Sat, 14 Aug 2004 08:29:14 -0500, "Bob Paulin" vaguely proposed a theory ......and in reply I say!:

remove ns from my header address to reply via email

I believe the torch is meant to be lit before application.

I also reckon the "friend" who suggested this should be invited to try it themselves.

***************************************************** It's not the milk and honey we hate. It's having it rammed down our throats.
Reply to
Old Nick

I believe that would be like a comparison of 110v. and 220v. One will kill you. The other will only blow off a few fingers and knock you unconscious for a while.

Or was that vice versa?

It's been so long since the explosion, I don't remember.

Is the phone ringing?

bye

.......................

steve ........................ ;-)

Reply to
SteveB

wash tank with hot soapy water, then fill tank with water 95%, position tank so air pocket in the weld area, and weld your area.

Reply to
Tony

Keep the cap off and you wont have a problem... I watch my friends at the junkyard cut up barbecue gas tanks... All they do is take a hammer and knock the valve off with a hammer and while the gas is coming out they cut the tank in half... Not something I would want to do...

Reply to
Kevin Beitz

If you live in a larger city you can probably buy dry ice. A couple ice cube size chunks of dry ice in the tank will fill the tank with CO2 and displace any gas vapors. Then weld away. Put some in a cooler with your beer and you can have a reaaaaally cold beer after the job is done. DL

Reply to
Gunluvver2

220V merely tickles.....its what you're used to that matters...

Steve

Reply to
Steve Taylor

Tickles, my ass. Try it hot and sweaty lying on your belly and brushing a 3 phase feeder. With very little room to maneuver away from it.

Garrett Fulton

Reply to
gfulton

Brrrrrr...the memories of something similar still haunt me....

Gunner

Reply to
Gunner

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.