Hints for welding motor cycle tanks

Fill it with water , roll it around so your weld area is on top , and purge with CO2 or other inert gas while welding is the safest way . IF you can wash it out with strong detergent and very hot water until the gasoline aroma is mostly gone then purge as above it should/might be safe to weld on . Might help if you told us exactly what you're doing , fixing a leak , modifying , etc .

Last time I did it, I washed the tank out with detergent and water a few times and then purged it with argon while I welded it. No pops, bumps or drama, it just worked. I used argon because that is what I had available.

BobH

Flood it with water. Flood it with argon or CO2. Use materials that are brand new to make special tanks like they do on OCC. Mainly, get everything out of there that is combustible, wash it out, and flood the space that can form any explosive gases. Even a small tank can pop pretty good with just a little bit of residue, if the proper steps are not taken.

And then, with some projects, it is just better to take it to a professional. Yesterday, I took my tandem trailer in to a specialist, and had the axles straightened and aligned. 100 ton Hunter alignment rig. I paid him $140, and drove away feeling great that things were right, and that there was absolutely no way I could have done the same thing, no matter how good and smart I am.

If the part is worth it, either pay a professional, or spend the bucks to get the proper specialized equipment. Welding on any tank is a specialized deal in the welding field, and really easy to either foul up, or get hurt.

I have learned not to fool with carburetors or automatic transmissions.

Steve

It is truly no big deal, fill it with inert gas and cap with shrink wrap or something that can expand and let the gas out.

I was contemplating angle grinding all the seams (which I suppose could be done full of water) then working on the two halfs, the problem would come welding the halfs together again as you hear stories of fuel tanks filled with water for years blowing up when emptied and welded.

If you were to cut it apart with an angle grinder and then waved a rosebud over the two halves you will likely ignite any and all fuel that may be lingering there. then the tank would be perfectly safe to weld.

Back when I was in the A.F. they had a policy of removing a fuel tank draining it and steam cleaning it and welding when the tank was still hot. which also might be doable.

Well , if he's gonna cut it open to work on it there little chance of vapors remaining inside . BTW Fred , what kind of motorcycle ? I have a tank for my '39 H-D WLDD that needs some serious straightening ... I started to cut it open years ago , but at that time was limited in welding equipment so stopped .

I am with Iggy. If you fill it half full with water and some Dawn detergen t, shake it and pour out the soapy water. you will get out almost all of t he combustible material. Estimate how much gasoline remains. And how man y btu's that amount of gasoline has. So almost no energy. And then you us e inert gas,so even less energy possible.

Welding on a installed auto gas tank where you can not clean in , is anothe r matter.

Dan

You hear about the fuel,oils impregnating the metal and then becoming liberated when heated. Don't know if this has any basis.

It doesn't.

ONLY weld with ER70S-2............ER70S-6 floats up impurite's leaving micron pinhole leaks destroying the paint down the road

I had a friend who welded gas tanks and just filled them up completely with gasoline and welded them. He said as long as the tank was completely filled with gas it couldn't explode!

I once worked in a building that also housed an ice company. They often sold dry ice to companies digging up gasoline tanks. The put a couple hundred pounds of ice in the tank and as it sublimated it pushed all the air (oxygen) out of the tank.

WARNING: if you do this don't install a cap, it will explode.

On one delivery, the secretary loaded her minivan with dry ice. Luckily, she figured out why she was getting confused before she got in an accident.

Mikek

She must have been breathing pretty rapidly too as it is CO2 that triggers the breathing reflex, not lack of oxygen. Eric

Huh ? Eric the CO2 pushes out the O2 as the heavy gas flows on the floor pushing the O2 out the top / window cracks or opens. When lack of O2 sets in the CO2 is over the limit and yes not having O2 but breathing CO2 will kill you thus reflex prior to serious issues. She would be breathing faster since she needed more O2 and could not get enough.

An interesting thing I saw today was a milk truck moving down the highway towards the distributor. The humidity was new 100% and the fog coming out the back door trailed behind at least a car's length. Cars kept back out of it - likely knowing or having engine trouble with it. Cars don't run on CO2 either.

If hot enough, CO2 will burn. But the molecule (not atom) has to be split. And once done, the carbon burns and makes CO2. Vicious cycle.

Martin

I have this bridge ...

Low oxygen concentration does not make one breathe faster. As the oxygen concentration falls you just get sleepy. Eric

Which is why nitrogen storage can be so dangerous. You don't feel short of breath, but just keel over when you run out of O2.