[NicknamedBob]

"Er...if they’re “outside,” where do they get the oxygen to weld a good seam? I know there are oxygen tanks, but for a fire to be hot enough for a weld, it needs air."

They use electric arc welding. It works just fine in space (vacuum).

You're probably thinking of gas-welding, as with acetylene. That's often done underwater.

[Monkey Face]

Ah. I knew if I asked, you would ‘splain things to me so I could understand it. You’re SO good, Bob! What would I ever do without you?