weave vs. string

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Hi, my first post, but I've been lurking for a while.I did industrial maintenance type welding off and on for 20 or so years, and enjoyed it, but realized that I didn't have the eyesight or coordination to become an exceptional welder.   I accept my limitations, but still enjoy welding anyway.   These days I'm a hobby welder, doing little projects around the home shop.   I identify with farmersamm's threads (and I hope farmersamm takes that as a compliment).Anyway, I was discussing a bucket repair project on another forum, and received some flak for weaving a 7018 cap.   One person who is a professional welder, and who specializes in bucket repair, told me that he has to work to codes (he lives in Canada) that require stringers on buckets, that his customers will reject a bucket that has a weave, and that weaves are apt to cause cracking.   Another poster told me that ASME code requires stringers.Those comments surprised me, because I've always seen 7018 caps made with a weave or some sort of oscillating pattern.    Admittedly, I'm new to bucket repair, though.   In my case, this weld was a non-paying job that I was doing as a favor for a neighbor, so I don't have to conform to any code except my own.   Still, I take pride in my work and want to do the best I can. Here are the pics that started the discussion.   A crack on a backhoe bucket.Crack ground out (probably not as thoroughly as some as you would have done, but ground nonetheless)A root pass with 1/8" 6011,95 amps DC+, was then capped with 5/32" 7018, 160 amps DC+,   using a Hobard AC/DC Stickmate.   As you can see, I used a slight weave on the 7018, to make the cap wide enough to span the root pass and tie both sides of the crack together.   I know it's not the ultimate bead, but that wasn't the point, the point was that supposedly weaving is a no-no and will cause cracking.Most of this bucket is made with mild steel, but it's possible that the cutting edges may be an AR-type material.   I can cut it with a file about as easily as mild steel, so if it is AR, it's not a very high grade.So my question is, what are your thoughts on weaving vs. a straight string ?    Pros and cons ?    Bear in mind that a larger rod is not an option with the Stickmate welder.
Reply:Pipe welding to code calls for stringers, but, there is a weave involved to a point. If you've ever welded 7018 uphill, in order to tie the edges together w/o undercut, there is a slight weave. Another rule for 7018 is that width of the bead shouldn't ever be more than 1 1/2 times the diameter of the rod. With that rule you can see that a slight weave is acceptable. With that in mind, do it however you feel comfortable. Welding cracks in backhoe buckets is an on going job here with the rock we have to dig thru. When it's all said and done, stringer beads with LH 7018 makes for a stronger weld.Only when the last tree has died and the last river has been poisoned and the last fish has been caught will we realize we cannot eat money.                                         -Cree Indian ProverbSA 200 LincolnVictor Torches
Reply:id agree that stringers make for a fine weld. id also say that weaves (when done correctly by a good welder) are very strong as well. i think maybe your friends who told you weaves cause cracks might not know what theyre talking about. weave beads when kept on the narrow side are good welds. the only thing d1.1 says about stringers vs. weaves is that it is an essential variable for requalification and that weaves should not be used on quenched or tempered steels. this could be because weaves put more heat into the base metal. you will get less weld shrinkage with weaves when compared to stringers though. touchy matter here and im sure you will get quite a few good responses. every welder has their opinion about stringers vs. weaves. i say use the technique that you do best!
Reply:The ASME boiler and pressure vessel codes including B31.1, ASME Sec VIII, and ASME Sec I do NOT restrict weaves or require stringers. Individual company practices, job specifications, material requirements etc MAY dictate what should be done. Welding Procedures may restrict weaving or thay may just say "Weave or Stringer". Weave beads are addressed in D1.1 only on procedures in which impact testing is required. For other procedures bead width may even be unlimited (SMAW in the vertical Position Table 3.7) . For FCAW in the flat position for prequalified procedures the width max is 5/8" but jumps up to 1" for vertical.Some materials are very forgiving for higher heat input, others are less. The variable that is more accurate to control is the heat input in KJ/In. This value is also addressed by ASME and AWS for qualification of procedures.  Just because a bead is wide doesn't mean its high heat input. Very thing beads can be applied by weaving. Try this. Get a piece of 1/4" plate and run a vertical bead on the plate using 1/8" e 7018. DO NOT weave at all. See how far you go and how much electrode is burnt off.Then do another bead on the same size and thickness of plate using a side to side motion that spreads the metal out eavenly . Pause on the sides, fast across the middle. Very tight Arc. Then compare how far you went with similar electrode burnoff.  Is the "Weave Bead" that much greater heat input ?There are MANY sides for the various welding wives tales that go around. Some have basis in certain materials (T-1), Organizations (Navy), and people (what my instructor said). Some have a good engineering reason for doing them but may not matter in certain applications. On a D1.1 note not only is the width controlled sometimes, so is the maximum pass thickness.And to add, production rates may vary with one method or the other depending upon nthe application .  A short large single pass fillet weld can be completed faster than a multipass of the same size since fewer stop and chip sessions are involved. But Arc TIME is exactly the same.Stringer beads on a test plate can minimize the number of starts and stops within a joint but INCREASE the number of beads you must fill the groove with .Last edited by gaustin; 07-17-2009 at 02:29 PM.Reason: Added last the para-Spelling ErrorHave a nice dayhttp://www.weldingdata.com/
Reply:When I used to weld on mining equipment we were not allowed to weave anything...ever under penalty of death. Those were the foreman's exact words. Weave and die. We were welding all AR plate though. Anything that got weaved got instantly rejected by the mine and we had to haul our mobile rig out there and fix it. Only had one guy ever weave anything that made it out of the shop. He got fired about 30 sec after he got back from fixing it. Heavy equipment people seem pretty hell bent on stringers so I'd go that route.The reasoning being that slag can get trapped a lot easier and "pepper" if you are weaving wide enough for the puddle to solidify before you weave back to that edge. (that was the reason given to me) We had quite a few arguments about this subject since most people who worked there were or had been D1.1 certified for unlimited thickness. I personally, have never gotten certified in D1.1 though. We weren't allowed to whip either for the same reason.Last edited by i4sillypwr; 07-17-2009 at 02:28 PM.
Reply:Gaustin hit the nail on the head.  Some of you would sh*t your pants if I showed you pictures of some of the weaves we have here on site on B31.1 power piping branch connections, particularly those which were welded with a semi-auto process in the shops.
Reply:Originally Posted by i4sillypwrWhen I used to weld on mining equipment we were not allowed to weave anything...ever under penalty of death. Those were the foreman's exact words. Weave and die. We were welding all AR plate though. Anything that got weaved got instantly rejected by the mine and we had to haul our mobile rig out there and fix it. Only had one guy ever weave anything that made it out of the shop. He got fired about 30 sec after he got back from fixing it. Heavy equipment people seem pretty hell bent on stringers so I'd go that route.The reasoning being that slag can get trapped a lot easier and "pepper" if you are weaving wide enough for the puddle to solidify before you weave back to that edge. (that was the reason given to me) We had quite a few arguments about this subject since most people who worked there were or had been D1.1 certified for unlimited thickness. I personally, have never gotten certified in D1.1 though. We weren't allowed to whip either for the same reason.
Reply:Depends on the job for me, If I am doing moment connections that are going to be X-rayed I will run stringers. All a bucket does is dig in the dirt, and most guys want the repair as fast and cheap as possible. I did that repair over 4 years ago and it is still holding fast.Disclaimer; "I am just an a$$hole welder, don't take it personally ."
Reply:mtngun,Brother, its a little hard to tell from the pic, but do you have access to the back of the crack? If so, I would have recommend gouging and, or grinding from the back into new metal, after you ground and welded the front side. From the look of the weld I would say it was a little on the cold side. It's never a bad idea to preheat, to improve penetration and minimize distortion, and when in doubt, run the amps a little hot. As for weaving, or stringers; stringers are better on the flat, but if you have run multiple stringer passes in the grove and the cap pass is no more than about twice the flux width of the rod, a weave is ok to do. Another little trick is to burn or drill a 1/4 to 3/8 hole at the end of the crack. Almost nobody ever does it, but it creates a flexible radius which divides the stress that made the crack in the first place. Also, as you lay in passes, peen the hell out of the new weld; it de-stresses the new metal. Allow to cool as slowly as possible; and post heat if you can.
Reply:Maarty, I do have access to the back of the crack, and I have been thinking about grinding out and welding the back side, too, even though the crack did not go all the way through the metal.  My own critique of the weld is that I was traveling too fast, something I do out of habit because most of my welding experience is with thin metal where you burn through if you linger in one spot too long.
Reply:I always drill the holes and I have read somewhere - it may have been in Lincoln's book - that you should alternate welding from each end to the middle. Does anybody do this ?
Reply:Mtngun,The thing is, unless you do liquid penetrant testing (the two part liquid kind, purple) you can't necessarily see the crack. You might think you see where it stops, but its really still there. Back gouging, or grinding is a good idea, whether its a pressure vessel or a repair. Going too fast is almost the same thing as welding too cold: the heat doesn't have time to sink in (penetrate). The puddle should have a nice oval shape with a rounded vee trailing edge. If the puddle makes a sharp vee at the trailing edge it's too hot. You will know its too hot because the rod will over heat, the arc will blow around and you will have lots of spatter. 6010, I like to start my welds at the edge and go inwards. Sometimes a run on tab helps.
Reply:Originally Posted by mtngunSo my question is, what are your thoughts on weaving vs. a straight string ?    Pros and cons ?    Bear in mind that a larger rod is not an option with the Stickmate welder.
Reply:There are different kinds of weaves. When the rod pauses side to side over a short distance - say double the width of the rod - and adequate pause time is used, a very repectable weld can be had on the flat. The reason for doing so is usually to cap off a groove that might be too small for two stringer passes. Penetration is a result of rate of travel, amps, closeness of arc, polarity , etc. A weave on the flat that is very wide, say 3 to 4 or more times the width of the rod is not a good idea. Not because it won't penetrate, but because wide weaves are essentially short stringers laid down next to each other consecutively. The problem here is that once the rod travels back to the other side of the weld the slag from the previous pass has chilled, and the risk of slag inclusion increases. Also the large heat affected zone of such a weld may distort the metal more than stringers. If your arc is going through the puddle your rate of travel is too slow.
Reply:Originally Posted by SupeGaustin hit the nail on the head.  Some of you would sh*t your pants if I showed you pictures of some of the weaves we have here on site on B31.1 power piping branch connections, particularly those which were welded with a semi-auto process in the shops.
Reply:so how big are these weaves lol? I've gone at least 6 inches wide vertical up before.
Reply:way too wide....whoa!
Reply:Originally Posted by i4sillypwrso how big are these weaves lol? I've gone at least 6 inches wide vertical up before.
Reply:I've seen some pretty massive tube to header welds myself. Big welds with "Nice Personality".Have a nice dayhttp://www.weldingdata.com/
Reply:Originally Posted by SupeSome of them you'd be lucky if you could measure with a ruler.
Reply:my goodness i have never heard of such a thing as a 6" wide weave. i have got to see pictures to believe it. somebody please post some!
Reply:Most guys know that "6 inches" is what they tell their women, but it's probably more like 2!
Reply:haha good point.
Reply:The widest weave I ever saw was about 3 inches, on a bracket of a boom on a boom truck. 5/32 7018 rod all the way. The long axis of the weld was 6 inches. This was joining 2 inch thick flat bar to heavy wall pipe of about 12 inches in diameter. The pipe being the vertical section of the boom, and the 2" by 6" flat bar being the bracket to which the hydraulic piston attached to. Lets all agree there are no hard and fast rules, and that every situation is different. Rules are general practices that are relevant to most situations, but not all of them.
Reply:ill give you that, but there is no sense making a weld that wide when you can blend 3,4, or 5 of them together to make the weld of the desired width. i cant see keeping the puddle a puddle over that wide of a span. never tried to weave that wide though.I've seen them done by people that have a hard time carrying a puddle in the vertical direction. I have started out students in the past with wide weaves and then narrowed them up as they got better.Have a nice dayhttp://www.weldingdata.com/
Reply:If I have my camera on me next time I'm in one of the laydown yards, I'll see if I can grab one.  Probably not though.  If I have my camera on me when I'm out there, I'm probably in a bad mood and out on a mission
Reply:As someone suggested, I ground out and welded the back side of the cracked piece, even though the crack did not appear to go all the way through to the back side.Back side of crack.I ground the cracked area approximately 1/4" deep and 1/4" wide -- but forgot to take a picture after grinding .   Then a root pass of 1/8" 6011 at 95 amps DC+.The root pass was lightly ground to clean up the slag and knock off the high spots.1/8" 7018 was drug without weaving, 125 amps DC+.   Sorry, I forgot the dime.   It was impossible to avoid burning through the cutting edge, since the metal thickness was tapered to a point on the edge.  Dragging makes it easy to produce a decent bead, but ...... since I couldn't see the crack, and wasn't sure precisely where the crack was, my backside weld may have missed some of the crack.    And that's one reason why it is tempting to weave a wider bead, to improve the odds of hitting the crack.I spent some time reading some of the tech literature on welding AR plate, even though I've only welded AR once in my life.   The SSAB site offers several excellent guides on how to avoid cracked welds in Hardox.   On the one hand, they don't say a word about weaving vs. dragging, and you think they would speak up if it were that important.   On the other hand, they do talk about avoiding too much heat input and avoiding a bead that is too wide relative to its depth.
Reply:One thing I noticed about your root pass, is that you didn't fill well at the end. It looks like the bead is just piled up in the center and not tied into the side walls. I'm betting you had slag trapped in the circled areas on the sides that may have been trapped by you cap pass. This is where a slight bit of weave or 2 passes might have been better. Attached Images
Reply:The puddle wasn't that wide, but the weld was. I guess you would have to see it. It was a flare bevel weld, with a two inch depth. The face of the weld was 3 inches, and the depth 2 inches, and length 6 inches vertical. It isnt necessary to maintain a 3 inch puddle. It looked good too. About 5 or 6 passes. Multiple weaves next to each other would have looked like crap.