while doing some research on welding SS I came across a thread on Miller Welding's forum about welding keggles and back gassing. A member claims he purges his kegs with dry ice before welding? I was under the impression that ss would oxidize in the presence of CO2. Any thoughts?
Dry ice for back gas purging?
- Thread starter pickles
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pickles said:
If you wait more than 27 minutes, someone who knows something about welding may chime in.
I know nothing about welding, but I'll offer this:
We use CO2 to protect beer from oxidation. Don't kow why it wouldn't work for SS.
We keep CO2 in stainless (kegs) for long periods of time, with no worries.
In fact, I'm struggling to see how CO2 would "oxidize" anything, as oxidation requires O2.
Should be OK. Some people use CO2 as a shielding gas for MIG welding
shafferpilot
Well-Known Member
a mix of helium and argon is preferrable for stainless welding.... but any gas that pushes the oxygen out of the way is exceptable for back gassing. On the weld itself, you MUST use either the helium argon mix or pure helium. Pure Argon won't work on stainless. It'll weld, but you'll never get a water tight weld.
Apologies, but argon is the purge gas used in stainless steel welding, both automatic machine welding and hand welding. Co2 should not be used for stainless steel welding or back purging.
shafferpilot
Well-Known Member
I would also be concerned with the temperature shock between the weld and dry ice. If that weld cools too quickly it will crack.
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