Pipe root pass

[ryan]

Hello there. Having an issue with my root pass and lookin for some input.

This is a tig root on 6" carbon pipe, 1/8 opening 1/8 fill @ 100-110 amps. My root is coming out flat with slight suck back (maybe 1/64 to 1/32). I know it's supposed to have a slight convexed appearance (like a wedding band) when done properly. I'm not certain what I'm doing wrong here. Usually I can get it to lay out correctly, not sure what I have changed to cause this. Any ideas?

Can too much side-to-side movement cause this?

Thanks for your time.

Ryan

[snoeproe]

What filler you using for your root? 70s2? or 70s6?

[74hotrod]

Are you "back feeding" the wire or just laying it in the gap? I would reduce my amps and allow a little more soaking on the bead.Also you can grind the flat bead a little more than normal and let your hot pass soak into and push the bead futher in if the root is already in place,but be warned the bottom 1/3rd of the pipe will have the tendency to suck back instead of going in.Can you have your fitter watch the bead as you put it in? If so then he or she can tell you whats going on during you root pass.JMO

[CEP]

Originally Posted by ryan

Can too much side-to-side movement cause this?

I use a 3/32 inch gap, with knife edges, and use 1/8-inch filler. I try to never let the puddle get any wider than the filler rod. I run 90 to 95-amps.

[aevald]

Hello Ryan, I am with CEP on this one as far as set-up. I know that others use different techniques and joint set-ups. You mentioned whether too much side to side motion could be an issue, I would say yes, the more that you walk up on the groove wall the more likely it is that you will draw the weld metal with you and away from the root area of the pass. I also watch my speed and look to move only slowly enough to see the edges of the bead fuse to the wall of the groove. Good luck and best regards, Allan

[ryan]

Using er70s2

I'll try reducing my heat. I'm laying the fill in the bevel. I'm practicing for a weld test I have coming up, so I don't have anyone to look on the inside as I'm welding.

Thanks for your input.

[angus31632]

hay bud
I like what CEP said but as for me I go for a tight 1/8 gap so that way when you get to the job you might get a sucky fitter or position and your 3/32 gap becomes 1/4 on one side and slammed on the other. I know that could happen with and gap but an 1/8 just gives you more room to play and if you get a big gap either back feed or go to a bigger wire. I'm just an apprentice so im sure if ive lead you in the wrong direction someone will strengthen me out and well both learn something lol btw good luck with your test bro im taking a 1" 308ss 6G test next week as my first weld test for a job but i do have a UA stick and combo cert from 72 so i kinda know i little something bout it.

[Coaltrain]

If backing off the amps doesnt work for you,you could crank the heat up. you can weld 70s2 hotter that 70s6. Also try a back and forth motion. It will push your bead in as you go. If you weld.hotter you can soak it in easier and push more wire. If you get a little flat, you can press your wire onto your root with wire with significant force while you hot pass. Just make sure you lay your wire back, not toward center of pipe, or you will push your wire right through your root. I always try to weld as hot and as fast as possible when i can. It will put a nice wedding band on the inside and blend your tacks in good. Hope this helps.

[slim83]

Just my two cents but I recommend a 5/32 gap and 95-110 amps. It seems to me that I get a better bead with bigger gap. It takes some practice but I guarantee it turns put more meat in there. Then crank up the hotpass and the bead WILL look like a wedding band. I wish I could post pics with my Droid but seems that I can't.

[lincweld]

the fitters at work fit a 5/32 gap, clean up the inside and outside an inch back and knife edge bevel. we are putting our roots in at 80 - 95 amps, clean your 70s-2 with scotch brite pad, wash side to side while pushing wire slightly. Doing this should result in a slightly convex root and and decent-size fill pass on 2 inch pipe. When possible, feed your wire through the pipe.

[pokerguy]

I just got done with school and all we were taught was 5/32 gaps. I never asked why but this might be the reason.

[Coaltrain]

3/32, 1/8, 5/32, 3/16, 1/4 inch gap... It just depends on what you are welding on,and how you are planning on welding it. Me, on small bore pipe, 1/8 gap 1/8 wire. One bigger pipe, 3/16 gap 1/8 wire... It will draw up by the time u get it tacked and get to the top. Just depends on the weldor.

[ryan]

Thanks for all the suggestions guys. I'll snap a few pics of my root tomorrow.

Do any of you add fill from the inside of the pipe? Can anyone give me a quick run down on how this is done? I'd like to add this skill to my tool box if possible.

Thanks for your time.

[WalkupManuel]

i would reduce my amps and allow a little more soaking on the bead

[JoeMayo]

I run a 5/32 gap with 1/8 wire. I run my amps a little lower around 60.. I freehand the root with a jumbo cup. I hold the wire half way in the edge and move it around when need be.

[Zca4]

There's nothing wrong with the root unless it has suck-back or undercut. It doesn't have to look like a wedding band, like some people say. If yours is wide and flat and you want it to look like a wedding band on the inside, you're going too slow. Pick up the pace, and barely go wider than the rod. Use a 3/32 gap and a 1/8 rod, just walk the cup faster than you currently are. It may take a little practice.

[astaindsoul5446]

Let's see a pic of the root.... That would help us more. Inside and out.
I run 1/8 tungsten and 1/8 filler at 120 to 130 with 3/32 gap.

[justinT]

You can feed the wire through the pipe if your gap is big enough to allow it :]

[gordfraser]

i dont get the "feeding from the inside"
i can do it. i know how its done.
But why?
what u going to do when you get to your tacks? or finish the pipe at 12 o clock?

feed it through a large key hole if you want excessive reinforcement

i like to freehand and lay the wire in the gap. stepping back and fore with the torch.
but thats only my preference

[alloycowboy]

This is a 316 ss bead on 4" pipe. 5/32 gap running 1/8 wire on 115 amps

http://weldingweb.com/attachment.php...1&d=1338338229

[CEP]

alloycowboy, that is just plain gorgeous!

[alloycowboy]

Thanks man... been doing this welding stuff for what seems like FOREVER

[CEP]

Well it shows, I think that is the nicest root pass I've ever seen!

[alloycowboy]

Oh yea.... you "feed" your wire on carbon.... but its best to "dip" your wire on alloys. Cause your not gonna feed wire on Inco 625.

Putting a good bead in depends on alot of factors. For me... a minimum of a 5/32 gap, NO landing what so ever. A #12 cup... bout 1/2 to 3/4 stickout on my tungsten... 110-115 amps.

If I feed the wire (carbon) I keep the wire dead center of my gap slightly below the feather edge of the bevel. When I get about 2 o'clock I put it even with the feather edge. Gravity will pull it down once you get up top.

Now "dipping" the wire is a different monster

[bgroves]

Im confused what is the difference in "feeding" the wire and "dipping" the wire.