3G 7018 open root butt joint test plate

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Hey guys my course finishes next week and I have the opportunity to test for a plate ticket. I want to test with 7018 in the vertical position and the only WPS available to me specifies 3.2mm (1/8) 7018 for the root, fill weave, cap weave and backing run, with 4mm back gouge allowed.WPS calls for open root, plates to be bevelled at 35 degrees (70 included angle), 1-2mm land, 2-3mm root gap, with 12mm thick plate.What I'm finding online either uses 6010 for the root and then 7018 rest of way out. Or if its 7018 all the way out theres usually a wider root gap with backing bar.I guess what I'm asking is what technique should I use for the root. I dont think Im meant to whip and pause like 6010, so should I just run a straight stringer or a slight weave?Tried a slight weave today and had some undercut on root run. Think my steps were too far apart on the fill weave, which left me with too much to fill with the cap. Not enough reinforcement in places.Was running DCEP 3.2mm rod at 95 amps.Any advice would be appreciated Attached ImagesLast edited by globetrotter; 11-13-2014 at 09:42 AM.
Reply:I would use a 2,5mm for the root run not 3,2mm but why do you worry about root undercut since as you said the WPS specifies a backing run with back gouging?
Reply:I'd want a heavier land for a 7018 vertical up root pass, 3-4mm.  But if you're bound to the WPS then use 2mm.  I would use a U shaped weave, climbing each side of the joint in turn.  Since you're back gouging, don't worry about trapping slag.  You're just trying to build a solid foundation for the first fill pass to build upon.I've even seen this type of weld made in the field vertical down; knowing that there's slag trapped everywhere with the 7018 rod.  They just count on back gouging to remove all that slag and get on with the job at hand. I'm not suggesting you do this on the test, since it's not a part of the WPS.Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:We only have 3.2mm or 4mm 7018 rods in the oven. Sorry I meant I had undercut on the top side of the root run. Not so bad that I couldn't fill it with the next pass, but not ideal.My lecturer also suggested a U shaped weave. Is U shape more prone to trapping slag than an inverted V or U shape?Like you say it wont matter on the root run because of the back gouge, but what shape weave would you suggest for the final stringer pass to fill the back gouge?Thanks for the replies Edit: it is reasonably relaxed, I think I could get away with a 3mm land. Maybe I should ask firstLast edited by globetrotter; 11-13-2014 at 09:38 AM.
Reply:A U weave with lots of vertical travel up each side of the joint might allow the slag to freeze at the bottom of the U.  then you're basicly welding through that slag as you move down and back up the opposite side of the joint.  I won't promise that you'll trap slag there, but I'd say the odds are not in your favor.Filling the back gouge will all depend on how deep and wide the groove is.  If you had 2.4mm rods, you might use 2 passes.  But not with 3.2 or 4mm.  I'd keep a really tight arc and use a standard Z weave pattern.  Just make certain you don't undercut the toe lines of that weld.  It'll be easy to do if the plate is hot.  You might want to let it cool before you put that final bead in.  Also, if you carbon arc to back gouge, take a grinder and clean up the groove.  Remove any dark colored deposits. Carbon arc gouging can leave carbon which can combine with the weld and make for a brittle weld.  Grinding removes this residual contamination. Shape the groove so you have good access to the bottom.Benson's Mobile Welding - Dayton, OH metro area - AWS Certified Welding Inspector
Reply:It's been ages since I ran any open root with 7018. I like a heavy 1/16” land, and use a 5/64” drill bit to set the gap. 3/32” 7018 around 65 to 70-amps. 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:This would be my advice and you dont need to gouge anything.  Zero land and just weld it.
Reply:Originally Posted by SvetsareThis would be my advice and you dont need to gouge anything.  Zero land and just weld it.
Reply:That was the back side
Reply:That was welded with 2.5mm, but you can use 3.2 mm also, its just a bit harder, usually at work I use 3.2 couse its faster to weld.DCEP when I have a good cap, and when cap is too huge to be welded with it, I change to DCEN.
Reply:Very impressive weld Svetsare! What size gap, and degree of bevel do you like to use?Don’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:We are in The United States of America why are we using mm when we should be using inches.
Reply:Originally Posted by CEPVery impressive weld Svetsare! What size gap, and degree of bevel do you like to use?
Reply:and please use mm instead of inches, Im so lost when you guys use inches here.
Reply:Yes and I get lost with mm I believe inches is still our our stranded. Let's use it as long as we can.
Reply:Originally Posted by SvetsareI like to have 2.5 or 3mm cap and bevel somewhere around 30 degrees. I use grinder for bevelling so its not so precise.
Reply:I don't think it is funny we are giving up to much.
Reply:Originally Posted by johnrbauerI don't think it is funny we are giving up to much.
Reply:Originally Posted by johnrbauerWe are in The United States of America why are we using mm when we should be using inches.
Reply:This is true all are not in the U. S. but why should we have to change?
Reply:You don't have to change. We will use mm and you can use inches.
Reply:Originally Posted by Svetsare...DCEP when I have a good cap, and when cap is too huge to be welded with it, I change to DCEN.
Reply:I think it welds little bit colder with DCEN then DCEP.
Reply:When doing procedural weld work, always follow the WPS! No changing from DCEP to DCEN, no running downhill when it's specified to run uphill, etc. Never deviate from the specified parameters because if you do and something happens, it's your ***.If I were to do an open root E-7018, I would put a 1/8" (3.2mm) landing on my plates, butt them tight (or an ever-so-slight gap) and weld out... *Reason* you are guaranteed penetration within 4mm from the backside (which is what you are allowed to back gouge). Then just back gouge to sound weld metal (which should only be 3.2mm or less making it within your 4mm allowed) and back weld it. -Hillbilly
Reply:Thanks for the suggestions. I tried the U weave on the first third of the root run today and didn't have much success (part of a root run probably isn't enough time to sort out the technique to be fair, but I started to worry about time). I did the rest of the root run with an inverted V motion but slightly rounded. I seem to have severe undercut when I do this weave. There doesn't seem to be enough room to pause on the sides because it all gets too hot. I can fill this undercut but surely this isn't ideal.I'm wondering if I should bring the root gap closer to 1.6mm-2mm (1/16-5/64), a 3.2mm (1/8) landing, and travel dead straight up with no side to side motion. Is this OK with 7018? Even when I see videos of 7018 stringers there is still a side to side motion being used. Quick question, if I do persist with the side to side motion on the root 'stringer', should the rod physically touch the sides of the bevels? I havn't been, but wonder if I should be.And sorry I meant I can back grind, not back gouge. My WPS (fairly relaxed with landing, gap and amps) says 95-115 amps for the root, 110-120 for the fill and 115-120 for the cap and backing run. 3.2mm 1/8 rod throughout. I found that too hot, ran 99 for the root and 105 all remaining passes. Thoughts?Will nick break and bend test a couple sections tomorrow morning and post results. Expecting trouble to be honest but will try and get another weld and some tests done tomorrow as well (hopefully with some more advice at hand ).Sorry for the long post guys I really appreciate the help.From New Zealand by the way, metric down here, trying to get to know both  Attached ImagesAre the photos working?
Reply:Yes they're working. Remember now, this is all about rod angle. You'll want the rod straight in, (90-degrees) to the plate, or slightly pointing down. Just like when you splice C-channel with the toes up. The rod is pointed down while your travel direction is up.I don't like to move 7018 around too much, I get porosity when I do that.You have to find what joint prep works best for you!Don’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:Your tie-ins (restarts) need work but your cover pass looks acceptable. Fairly consistent and not much undercut if any. More practice and you'll be there 100%.-Hillbilly
Reply:This is embarrassing.. after all of that, my arc length was too long. Had a different instructor watch what I was doing, he quickly stopped me and showed me how close I need to be. This was my first time watching someone and straight away I could see the difference. I should have asked sooner.I have always heard the importance of keeping a tight arc, and I thought I was, but I was never letting the flux lightly touch the side of the bevel as I go side to side like I am now (for the root). Undercuts almost gone Took less photos today but got a picture of my quick bend test, not perfect, not sure what that mark just off the weld is. Going to weld two joints tomorrow and send the best of the two out to get xrayed. Should have a result sometime next week.Thanks for all the help it's nice to have somewhere to speak with like minded people  Attached Images
Reply:Oh and how good an indication is a bend test compared to xray? That was a root bend. Would it break if there were minor issues or only if it was really bad?
Reply:Bend tests, and xray are kind of two different animals. For us they generally UTed the test plates on site first. If they passed the UT, then the test plates would get sent to the lab for bending and xray. If they let you prep your coupons, use an 80-grit sanding pad. Make sure all sanding lines run length ways with the coupons. Take a mil file and break over all edges. If you get to bend them, rub soapstone on the coupons before placing them in the bender. But don't tell anybody I said that!Don’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:Originally Posted by CEPYes they're working. Remember now, this is all about rod angle. You'll want the rod straight in, (90-degrees) to the plate, or slightly pointing down. Just like when you splice C-channel with the toes up. The rod is pointed down while your travel direction is up.I don't like to move 7018 around too much, I get porosity when I do that.You have to find what joint prep works best for you!
Reply:I have been using a slight push travel angle (rod slightly below level). Since tightening my arc gap up things have improved. Tested today, was last day of my course. Passed visual inspection  Now the plate gets sent to be xrayed and have two bend tests done. Should have a result in 1-2 weeks.Thanks for the help! Attached Images
Reply:One more! Fill pass Attached Images
Reply:Looking good!