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.
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
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.
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
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
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
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
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.