Need help tig 5g pipe

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Gap 1/8, wire same, heat 75. Problem is root has too much concave in the bottom from 5-7, the rest is fine. I run wire in the gap don't shoot the gap like my instructor suggest. I've tried but prefer in gap. Any suggestions would be appreciated.
Reply:Hard to say without more info, could be too long an arc length, incorrect filler rod angle, not adding the filler right in the gap or not adding enough filler rod to overcome the effect of gravity on the weld pool (amongst other things).
Reply:in my book (i always write down temps that work for Me so i dont forget) .. for overhead? 5g?I used 98 - 100 amps, 1/8 gap (i think) and 1/8 rod.. so the rod could fit in the gap kinda... and my technique was to go fast and only burn (or focus on) the rod. Like... dont try and wash the puddle into the feather edges. and go half fastsounds to  me, you might be going to slow at this section and like you said, getting concave on the inside root.Im no tig expert and of course your not using the same machine as i did.I remember that was my problem, id wash the puddle into the edges which meant i was hanging around this part for to long and i would get concave "suck back" i called it. My suggestion above is what worked for Me (. I used to get flush or slight reinforcement build upanyway, good luck
Reply:Does sound like to much heat and to slow a travel speed causing the concavity.  Looking at the position I'm guessing your right handed and working the tig torch with your right hand and the filler with your left.  This is the same spot I have a problem with on the 6G and you have to make sure that your focusing on putting enough filler into the root and each bad after that and not so much on the weave that your doing.
Reply:thanks for the replies, big mopar,3wguy, and pinza. i struggled for months on 5g, stick bc of the dam bottom, 6g two days!  my problem i belive was doing overhead groove, stick,my instructor ok'd me to slightly tilt my plate, and i never actually was doing a true overhead, which is still now giving me problems. travel speed to slow, too much heat, watching filler touch edges. keep my tungsten electrode 1/4' from cup, walk the cup, keep rod angle between 20 and 30 degree, gun between 70-80 degree, gap is just enough for the rod to fit in snug, temp between 75-80, 6' sched 40 pipe, and yes mopar i am right handed, stand almost directly underneath pipe, walk cup towards me, not so much left to right. i'll try turning my heat up, and moving quicker!
Reply:Sure, I'd rather do a 6g than a 5g with stick any day of the week. Turning up the amps a bit is probably a good idea, I normally run the root at about 100A with a 1/16 land  and a gap that's about 1/16 bigger than the filler rod when free handing schd 40 with tig.
Reply:when i did my 5g (do few inchs, move the pipe and continue OverHead throught the whole pipe) i used 98-100 amps all the waybut when i tig'd my 6 G i used 98-100 amps for OH and..when i moved into vertical / flat i changed my amps for each positionI also used a MUCH lower 3/32 7018 amp as my hot pass then if i put in my root with a 3/32/ 7018I have these temps written down also.. all of them.. but again .. its what worked for me (i can post them, if it helps)"and i never actually was doing a true overhead, which is still now giving me problems"me, if i had a problem with overhead tig root, (which is the most important part from what i have seen),  id show up at school and not take any breaks and practice until it was time to leave, or until i felt like turning into the hulk and ripping my booth apart.... then id take a break... ask my instructor for advice or a demo.. because. the slightest manipulation (different kinda zigzag hand motion, no washing in edges, faster hand motions) or amp temp that You (or me) dont know at this present time, will be the savior and key to frustrationyou'll love yourself for taking the time to learn the hardest part, Nailing it, and not "Sh!tting the bed" aka "F*cking up"  when you get a real job. as frustrating as it is, its very rewarding this is providing you want to learn and you have a good instructor.. (i want to be the best, but theres ALWAYS somebody better)again .. im no expert .. yetyou got me confused tho  "stick bc of the dam bottom" "stick,my instructor " are you doing stick root or tig? or are you sticking on with your tig? im lost at this pointLast edited by then3wguy; 06-18-2011 at 06:05 AM.
Reply:Everybody has their way. I can't run at 100-amps until around 4-inch pipe. I use a knife edge 3/32 -inch gap with 1/8-inch filler. This is 2 1/2-inch sch 40 5-G, at 85-amps for the root. Attached ImagesDon’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:What schedule pipe are you running?Your welding 5g and get (4) tac welds to position the pipe appropiately. I place the tacks at 12,3,6,9. Use that tac on the bottom (6) as a starting point and walk it as far up as possible on the wire. Depending on the pipe size carry it all the way to 12 or stop when you get uncomfortable and restart. I like to prep all of my tacs before hand and I weld right over them.My fit up and runout on doublewall is:Knife edge -- i.e. No landing3/32nd gap ~ and it sounds like this may be your issue? You want the gap to be smaller than the wire whenever possible IMO. 3/32nd gp and 1/8th wire allow you to lay the wire on top and simply walk over it. Thus breaking down the walls.1/8th fillerHeat 110Free hand it in or simply weave/walk it in making sure to grab the walls. I prefer to weave it in as I feel I break the walls down better.Last edited by jsm11; 06-18-2011 at 08:31 AM.1981 Lincoln SA 200Miller Trailblazer 302gMiller 211 Mig Welder w/ AutosetI'm learning to stick metal together
Reply:Pinza, my freehand could use alot more practice. lol! I use no landing either Jsm, but my gap is just big enough for my filler to fit in snug, i like to walk the cup w/o having to move my left hand, filler to much. Still  got alot to learn with tig. I will try using a smaller gap, when you say "lay wire on top" i assume you mean wire in the the bevel. Correct me if i am wrong Jsm. Im using 6inch sched 40 pipe, i tack same as you 12,3,6,9 and feather tacks before root!Looks dam good Cep! I must ask do you run your 1/8th filler in the bevel or on the back side of gap for root? I've only practiced on 6inch pipe, sched 40 and 80. Hope to get to some two inch or 4.                3wguy i also roll my pipe to practice on the oh portion, it was really weird the first time i ran 5g tig my root was dam good, then after that first i just couldn't repeat what i had done, like you i keep my temps written down. Prolly was just trying too hard and staying in one spot too long. But hey if ya dont mind posting your temps, i'll plug em in and see how they work for me. Trust me the only reason i take breaks is bc our instructor comes around turning off all the machines at break, i hulked out on about 3 or 4 diff rod holders. Lol! I'm ok with keeping my cool now though.I don't move up until i am confident with my own ability to do a solid weld and or fix my screw ups. I spent the better part of a whole dam semester on 5g pipe, stick alone, if my root isn't acceptable i fix it, i don't understand my fellow students as soon as they screw up on a coupon they'll go cut another?  Wasting time and steel imo. "stick bc of the dam bottom" "stick,my instructor " are you doing stick root or tig? or are you sticking on with your tig? Sorry that is a little confusing, currently doing tig all the way out. Was referring to when i was doing stick on 5g how much trouble it was giving me.Going in monday trying a couple diff things will post.  Happy fathers day to all those fathers!
Reply:Originally Posted by weldinwesLooks dam good Cep! I must ask do you run your 1/8th filler in the bevel or on the back side of gap for root?
Reply:just did a 6G 100A, 3/32 gap (so the 3/32 filler wouldnt go through), kinfe edge and had to use 3/32 filler as there was no 1/8" rod. Worked fine.layed the filler in the grove on a tangent to the pipe and ran the tungsten over and then back, over and back. had slightly convex on the bottom half.worked for meG
Reply:3/32 gap, 1/8 filler, heat 100. Thx Jsm! Problem solved.
Reply:For me 5g is very hard until you suss it, I have spent nearly 3 weeks practising at work because we haven't much work on. For one you have to get the right amount of reinforcement like on the bottom of the pipe and on the top of the pipe you want slight reinforcement due to gravity with your hot pass and fills and cap, too much reinforcement is a failure plus too little, plus how do you know how much reinforcement is going in
Reply:IMHO...a couple basic principles that newbies should be clear on.  We except that when doing a 2g, the weld technique stays basically consistent all the way around....slight changes as the coupon heats up.  Totally different with 5g.  On top the arc motion is high up the bevel sides at a speed that just melts the filler when crossing over.  Filler can be just laying in snug gap.  Or if the filler is undersized then it can be fed higher up the sides and bridged the proper amount.  The latter is more difficult but needs to be learned for uneven gaps.  Exterior appearance would be concave.On the bottom it's either thru feeding higher inside the bevel or simply heavy feeding until the puddle convexes inside and out.   Far more filler is required on the bottom.  3 to 5 times as much as on top.  Arc motion is just to the edges of the bevel gap....very little side to side....the puddle 'bulges' up the sides to tie in.  Exterior appearance would be convex.  Expect some grinder touch-up on bottom and then even fill all around with hot pass.