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Up Topic Welders and Inspectors / Education & Training / whats a good tig root look like
- - By Eric385 Date 09-30-2008 19:39
ive already done stick pipe and mig overhead and now im doing tig at school. my question is, all the other students in my class that are doing tig have roots looking, i thought, terribly. they look like they have suck back and real chopy. my instrutor said that this is a good root. im not to sure. i thougt that tig was suppost to be a nice looking weld and i can do better with stick. im almost done with school and i dont want to get out there and find out i suck.
Parent - By swsweld (****) Date 10-01-2008 00:52
Eric385 picture a wedding band.
That is what the root pass on the inside of the pipe is suppose to look like. Tacks all fused. Approximately 1/16" penetration  and smooth as glass.
Parent - - By medicinehawk01 (**) Date 10-02-2008 02:22
Like Tim says, it should look like a wedding band. The thing is, you too can put in a root like that everytime. Here are the things you need to do to make it happen: Prep & Fit-Up = clean up all the mill scale, use a knife edge with even a 1/32" land (no more than that tho), Fit it up using a 1/8" gap and IF it is slightly bigger, that's ok, but not really necessary. So many times I have seen good welds gone bad because of lack of the basics being followed. I am guilty of this  too, it's why I am telling you about it. So, you have 4 tacks on the joint, and have ground or feathered the edges of the tacks, now you're ready. Right??? Ok, wait. Look at the joint carefully. Take your 1/8" rod and see if it will go into the joint. Does it? In all 4 quarters? It has been my experience that (usually, no matter how hard you try) there is one quarter that is tigher than the other 3. That is the quarter you want to start with. Light up in the middle of the tack preceding your tightest quarter and at the same time get your rod at the end of the tack. Now here it is, the "Trick" to making a perfect tig root on pipe (carbon steel) MINIMIZE the ocillation of the torch. You need to be watching the welding in front of you carefully......whether you "walk-the-cup" or free hand, you only move the arc to melt the wire to both parts to be joined.
The reason other's have "choppy roots" is because they are moving the weld pool around way beyond where it should.
More specifics? Use 120-125 amps DCSP. I assume you are welding schedule 40 carbon steel pipe, so your tungsten should be stick-out   5/16". IF the fitting or pipe is different in the inside diameter, just be aware of this and know that you may have to linger (on the side where the inside diameter is smaller) here slightly longer. Really tho, you'll have to be travelling at a pretty good clip. IF you don't get penetration (using the parameters I have specified) you are moving too fast. IF you start opening a hole (in the joint) you are moving too slow. Watch the puddle, IF every thing is going right, you can see the puddle swirling only slightly larger than the root opening.
There has been alot written about this subject, so look it up and you'll find many good posts with lots of good advice. I am only relating what has worked for me and others I have taught. So,
Good luck with that.

Be well,

Hawk
Parent - By flange jockey (*) Date 10-03-2008 23:04 Edited 10-03-2008 23:29
eric heres a few that have passed x ray
Attachment: 011.JPG (142k)
Attachment: 036.JPG (69k)
Up Topic Welders and Inspectors / Education & Training / whats a good tig root look like

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