On Sat, 16 Jul 2011 19:29:34 -0500, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

fired this volley in
:

Water can't do this. CO2 can. Argon can. Even Nitrogen can.
If using auto exhaust, you need a large (roughly 2 inch ) hose, a well
warmed up and properly running engine, and several minutes of purge
before starting to weld - with the exhaust still flowing.

You've never actually done this, have you Clare?

LLoyd
Lost count how many gas tanks I have repaired. Used exhaust for quite
a few years - then started using CO2. Using a garden hose from an auto
exhaust, most of the exhaust bypasses the hose unless you pack around
it with rags etc. I used to just put the shop exhaust hose over the
tailpipe, and connect it to the filler neck withthe tank unit out and
let it run a few minutes,until the tank was warm - then start brazing
(or soldering)

I've tried water too - but unless you are going to arc weld, there is
way too much thermal mass.. With CO2, it is DEAD SIMPLE. And the
repair can even be made on the car if the leak is not on the top of
the tank, you can reach it to clean it, and there is nothing flamable
too close to the tank.