[rob2isking]

How is everyone. Glad to be here, this is an awesome forum with lots of knowledgeable welders. I love tig, done ss sheet metal for awhile. Doin cs pipe on my own now. I am getting internal concavity. Using 3/32 gap with same filler. Should I use bigger gap and filler or same size fill with big gap? Or??

[Otto Nobedder]

Welcome to the funny farm!

3/32 gap and filler are typical. You'll hear that concavity called "suck-back". It may mean you're putting the root in too hot, especially if it happens at the bottom of the pipe,while you're welding overhead.

If it happens in all positions, you may need to feed more rod during the root.

Post this over in the TIG subforum, and you're sure to get a lot of suggestions.

Again, Welcome!

Steve S

[Alexa]

Rob2isking.

Do you note the concavity immediately after the root pass?
After the second pass?

Alexa

[Otto Nobedder]

Good point, Alexa,

This can happen in the hot pass, with too much heat/not enough filler, or both.

Steve S

[Mike]

Welcome to the forum.

[rob2isking]

Using the lay wire, do u just walk over the filler or do u shove in a little as u walk over it. Cause ive heard Jody say keep downward pressure so I thought u just walk over it. I think my heat is around 80 so I figured is was cold enough for sch. 40. I will post this on tig too thanks ppl for ur replys. Yall are the greatest

[rob2isking]

To alexa, on the root pass, I noticed suck back
And some incomplete penetration. so I didn't run a second

[Alexa]

http://www.weldingtipsandtricks.com/tig ... -back.html