motorcycle gas tank welding -advice needed

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

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wallster wrote:

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.

Have you ever personally done this, Dave?

Jim

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

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

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

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.

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.

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

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".

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......

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

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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.

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

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.

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...

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

Steve

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

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

Gunner