[AKmud]

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...

[GreinTime]

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

[RichardH]

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

[mcoe]

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

[Otto Nobedder]

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