Welding Tips and Tricks

I asked this over on WW and didn't get much for a solution...

I was building a small aluminum rack for a customer today. Simple design, thin wall 1x1 square tubing for most of it. I tigged it together and each time I tried to finish the last weld on a piece of tubing, it would blow out from the hot air pressure being trapped inside these short (6") sections of tubing, leaving a pinhole that was impossible to close up. I finally drilled some relief holes that would be hidden so I could finish the beads.

Is there an easy way to deal with the pressurization? I'm not sure what I would have done if I wasn't able to have the relief holes...

As far as I know, not really. What application did you have in mind where you wouldn't be able to drill vent holes?

I wish I could remember what thread it was where they were talking about welding on old decommissioned cylinders. I want to say that they had talked about something similar, but at 22 I'm getting senile in my old age

I did a small tube rack recently. Drilled a small hole (like 1/16") under each coped joint, which became hidden inside the joint and joined all the air spaces together. On the last joint I drilled a hole just behind the start of the bead, which became the last point sealed as I came back around to finish. That was also the last joint on the project, so no heating of a sealed container.

FWIW,
Richard

I would probably weld the whole thing up except for one bead/seam. Walk away and let it all cool and relax then go back later and weld that seam. That is just a theory and idea to try. Might work

If you have no choice but to close the space, and you have the room, have an assistant quench any accessible part of the cavity with a wet rag to rapid-cool some area as you rapidly "spot" in the pinhole. Build up some excess material at the pinhole first, quench, and BLAZE that pinhole for a half-second or less.

Steve S