Weld Porosity

[JBnID]

Tubing is sometimes tough because the heated air inside will blow out through the puddle.
Argon is heavier than air--when welding up tubing, try to have the open end of the tube up. Before welding the joint, trip the torch with the post flow set on 20 seconds or so and fill the tube with argon, then weld. If the tubing has to be open end down, always stuff a paper towel in the bottom to kill the 'chimney' effect that blows air on the back side of the puddle.

[inthefrey]

Tubing is sometimes tough because the heated air inside will blow out through the puddle.
Argon is heavier than air--when welding up tubing, try to have the open end of the tube up. Before welding the joint, trip the torch with the post flow set on 20 seconds or so and fill the tube with argon, then weld. If the tubing has to be open end down, always stuff a paper towel in the bottom to kill the 'chimney' effect that blows air on the back side of the puddle.

This is a GREAT tip! Never though of this but it makes complete sense. THANKS!

[zoama]

Heated air only blows through the puddle on tubing when you make the last weld to seal it. Always back purge stainless but on steel or aluminum you can leave a small opening on the last weld, then come back and close it when cooled without purging.