I see nothing wrong with tight, neat stringers vertical up. As long as there is no violation of the supporting wps or internal manufacturing procedures, this should be the welders option. I would rather see this approach than a wide, uneven "gorilla weld" deposited.
I do not know what code you are testing to. The AWS Structural Welding Code does not address this issue for SMAW electrodes. And Lincoln does not have a specified maximum weave width, although thier welding school teaches 4 times the diameter on a vertical-up weave.
As the owner of a welding business I often have the opportunity to not only discuss this topic, but I also teach many young, new welders some technique. I am hard pressed to find anything written in stone, and almost all welders will have a slightly different opinion or technique or both. With that said, my opinion is as follows;
Stringer beads have their place, when heat input is a concern (stainless..), ultimate strength (alloys..) and absolute minimum slag inclusions (x-ray quality) are needed a stringer bead may be called for. Even with all of those concerns I will still weave at least a little to flatten out the weld. Unless the above criteria or WPS dictates, I will almost always weave a cover pass. As to the maximum width of a weave, I have always maintained 3/4" maximum. I cannot remember where I learned that, but it has always served me well as a guideline. I hope this helps more than it confuses.
All things equal, I think that if a welder decides he or she likes to run stringers V-U, that's their own choice. I wouldn't see it being a problem in a manufacturing perspective, because you're likely to have similar heat input. Myself I run a weave bead because I can "slick it" in. Not that I can't do stringers, but normally on a time constraint it's faster to weave than it is to run stringers. Also with a weave bead, you can minimize the chance for porosity and LOF discontinuities. The more stops and starts, the more chance for error. And one thing I like to see during testing is a welder that breaks the arc to one side or the other, that way with a roll down tie-in you pretty much eliminate the porosity and LOF. I see too many welders, and some in training that want to touch start the electrode in the vertical up position, which is almost certainly going to give some sort of porosity or LOF. So basically, my opinion is that if the individual isn't turning out unsound weld metal, let them be. Also, I have always gone with the 3X's the diameter of the electrode, that way you're in the clear.
When I was working for Saudi ARAMCO, they limited weaving to 3 - 5 times the electrode diameter, depending on the electrode size. This applied to pressure piping/vessels and structural steel weldments.
After the Northridge earthquake, it became apparent (after lots of testing and evaluation) that large wash or weave beads did not perform as well as those performed using stringer beads. The AWS also noted this in their document issued regarding the Northridge Earthquake dated 11-10-95.
I recommend stringers to minimize the possibilty of throat cracks in welds subject to high restraint or high strength materials. Some materials will not lend themselves to weave beads as well such as aluminum.
We don’t want to forget the reason for testing a welder. It’s to determine if he can produce a sound weld or not. We do this by using objective examination criteria, usually from a code/standard including possible supplemental acceptance criteria in the form of a company’s written specification or testing procedure. As far as I’m concerned and from my experience, it’s unprofessional to use self-perceived acceptance criteria, examination requirements, or testing procedure which includes the words “I was told”, “I like to see”, “I don’t like to see”, and etc. These are examples of subjectiveness and have no place in the test booth or the job site. In addition, many times inspectors confuse production weld acceptance criteria with performance qualification acceptance criteria. Why let this happen when it can be avoided for the most part by determining “company policy” and writing a testing procedure, which would include any and all supplemental limitations, a company approves of?
As an example, I actually found I had a CWI/RT III who thought rolling a golf ball through a 2” sch 80 coupon was part of a Sec. IX test! If it hung up, the coupon was tossed, if it made it through, he would radiograph it. Do you think that was in the testing procedure? Did he inform the welder before the test what his limitations were? I can tell you what he did say when I interviewed the welder whose coupon I found him with. He told the welder he didn’t want to see a “gorilla weld”. Ok fine but this welder had come from the oil patch where his former company wanted a heavy root and cap. He wasn’t concerned about doing a “gorilla weld” because he’d never been accused of it before, so why would he be worried about this test? This welder’s test coupons were radiographed and he subsequently went on to weld for many years (still welding from what I hear) meeting the quality requirements of the B31.1 & .3!
My suggestion to you is if you want enact limitations such as to use stringer beads or weave in a test, fine. If you want to limit the width of weave, that’s also ok but make it part of the acceptance criteria before giving the test hopefully in the form of a testing procedure. Last but not least, be honest and make sure everybody understands the requirements up front.
Your intent is understood. I can give you an example of the acceptance criteria for a weld that does not address weld bead or layer width or thickness limitations.
I am currently doing a failure investigation on a piece of equipment using a Q&T - high tensile material with a yield of around 100 ksi and a tensile of 125 ksi. Weld profiles (depth to width ratio) caused the original failure of the welds in the form of wide-weld face. I have recommended repairs using only stringer beads. This is not "my" rule per say, but it will help mitigate any further problems with the weld quality. It has worked in the past on a number of weld repair programs that I have been involved with. In other words, the client has retained my services to make these recommendations as part of the criteria for the repair program. The recommendations are are approved by the Engineer and become part of the criteria at that point.
I know inspectors who tell the candidate they must wait 5 minutes between each pass, so the welder takes 8 hours to run a 1" test plate. Also know about the guy who says the A36 1" plate has to be preheated (while it's 80 degrees plus in the building where testing takes place).
I usually do not explain anything to a welder who is doing a performance or procedure qualification (stringer/weave/preheat/grind/pause), their suppposed to be taking a test...
I think all this is very good information but I believe the the answer to the original question is in the Procedure.
If the WPS says "Stringer only" thats pretty easy to understand, how ever if it does not address that issue then it must not be an issue.
If you are going to decide what is or is not "PROFESSIONAL" beyond what is in the WPS where will you draw the line? Dress,Clean shaven, Sex, Race or Creed.
Be "PROFESSIONAL" and stick to what you have documentation on.
Right-on DGXL and RonG,
As DGXL wrote- "I have recommended repairs using only stringer beads. This is not "my" rule per say, but it will help mitigate any further problems with the weld quality. It has worked in the past on a number of weld repair programs that I have been involved with. In other words, the client has retained my services to make these recommendations as part of the criteria for the repair program. The recommendations are are approved by the Engineer and become part of the criteria at that point."
That's exactly how it's suppose to work. The key words being "recommendations" and "approved".
Thank you for understanding what I was saying and providing the "on-target" example.
It's been my experience that's the "value added" our clients are really paying for. The ability, through our experience to help them create solutions to their welding related problems or avoid them from occuring!
I also put on my WPS forms stringer or weave along with a dimensional value (eg: 3 x electrode diameter). This leaves no doubt that the "rules" have been established.
Just my two cents!
I was a NDT Tech. for 15 years, (I shouldn't of stated that) from experience I have made more money x-raying welds that were weaved than welds that were stringered. I would say 75% more. I feel that there is a much greater chance of trapping slag and getting lack fusion. The problem I have seen, is that the welder tries to carry to much metal.
P.S. I would like to thank some of the regulars that reply to these postings. It's nice to know there are people out there that don't mind sharing there knowledge and experience. Thanks!
I really enjoyed reading this. I agree with seldom and Ron and DGXL in the whole professionalism aspect. I believe to be professional you must go in there and be the best welder/human being you can. But this isnt a subject of judement on the test. I know there are lots of welders who walk in to a test booth, take and pass the test and it was easy. There are others who pass it by the skin of their teeth. Do we judge these two differntly? No. If that guy who thought it was easy really did the best job he could, or sluffed off cause he knew he could pass does this make him any less qulaified for passing...no. He passed whether he could have done better, or whether he did the best he could. Likewise if I walk in there unshaved and long haired with tattoos versus a guy who walks in clean shaven, starched Red Shirt, python skin boots we shouldnt look at one welder as he should get the job and he shouldnt so grade them differntly. They should be graded equally. I personally keep clean shaven, short hair...not too short. :) And wear clothes that look what in my opinon is professional looking. This is a personal thing for me though. I want to look a certain way. It makes me feel better. I dont make better welds because of it. I also dont think I should get picked over another candidate on my clothes instead of my welding. I want to becredited as a welder for my welding ability. I want to be credited as a human of respectable nature for how I dress. I do a lot of contract welding. I do work for farmers, and some businesses. If I dress like a slob, they wont trust me. If I dress nice...they will. That gets me in door. But if I turn out a crappy product...they'll never have me back. Its a choice we all must make, but shouldnt affect passing a weld test. Sorry for my length, but I thought it worth saying
Most codes require the Welder Qualification test to be performed in accordance with a welding procedure specification. If the welder cannot perform within the requirements of your WPS then obviously there would be no need in hiring him. That by no means indicates he is unskilled or unprofessional.
Many silly "Wives Tales" float around about welding. Some of which may have originated in good engineering/welding practice and were carrried to another project in the minds of welders,inspectors,supervisors etc. High Strength Low Alloy steels can be adversely affected by excessive heat input. Wide beads usually travel slower an therefore more heat. More heat doesn't hurt all steel in all applications.
The effect of bead width on the "Quality" of a weld is related to many variables. Heat Input, groove geometry, thickness of weld pass (controlled by WPS), and shape of underlying beads, skill of the welder etc.
I was taught to weave no more than 2 1/2 times the electrode diameter, however, increasing that up to 3-4 rod diameters is possible along with integrity.
Whoever said "it's unprofessional to run stringers" could not have been a weldor. Have you ever tried to weld 12" dia.-schedule 160 which had a bevel opening (distance between edge of bevel to edge of bevel) around 1 1/2" while in the 5G????
You not gonna run a weave around that for a cap.
Anyway, having passed a few weld tests and joints passed radiographic inspection (per ASME B.31.1 & B.31.3 ) in my career (some of them I was sweating out for sure) it should be noted that if it makes it per the spec. it is noted on the inspection report "acceptable", meaning the weld is Good. It doesn't say "Awesome weld!" or "Borderline weld-hate-to-pass-it- But-it's-allright-weld!".......You see the point I am trying to make here is that it is our blood & sweat that goes into a weld and the satisfaction of passing a strict inspection criterion, but you won't find that on an inspection report and to Anyone who has passed any welds or tests......."Hats - Off " and Weld-On because it is Folks like us who keep the stuff flowing no matter which part of the world you are in.
You should be Proud of that!
Great topic!! As instructors this is probably the most common thing we hear. In D1.1, ASME, API etc.. we see references such as weld size, penetration, leg, porosity, reinforcement, underfill,undercut,acceptable weld shapes(convexity/concavity) etc.. but we have never seen a code reference as to "ripples and bigger motions". We have seen references, code and wps examples that limit motion, (for example max 6 times electrode width, so with 1/8" electrode would be 3/4") and several that have specified stringer beads only. We have never seen reference that says motion ust be used, when bend testing welds we find that motion creates more issues (flux inclusions, undercut) than anything else. Had a night class adult who was prepping for his 3g limited SMAW test and was having continual problems, Finally got him talked into "trying" stringer beads only. He complained about how much longer it took. Then we cut and bend tested and "wow, it worked". He too had been told that "you gotta use motion". Great topic
Is the attempt to create the "stack of dimes" effect the culprit in some of these cases where excess motion has led to problems? It seems to be a popular notion among self taught welders that you should roll the MIG torch around to create half circles. If you work with a slower weld deposition rate you can make it look pretty this way as opposed to a stringer using a more appropriate voltage/wire feed setting. It seems to me that even if you are somewhat uncoordinated, as I am, it's better to run a straight pass/passes although it may not be as aesthetically pleasing. Most of the robot fillet welds I see are slightly convex and have some inconsistencies at the start and end of the arc, yet they seem to be performing well.
Wow, lots of perspectives regarding this topic. I give WABO structural tests on both limited and unlimited plates. WABO is a Washington state organization that has it's foot in the door pretty heavy concerning the whole testing and certification game in the state of Washington. I have tried to nail them down on their views concerning weaving vs. stringers when making structural welds, the response that I get is that it is up to the disgression of the examiner. That being the case, I have the individuals that I test, make their welds using stringers. Here is my logic, if we were only welding on grade A-36 steels it probably wouldn't be as much of an issue if you were welding with weave beads because this grade of steel is not noticeably heat sensitive. More and more these days Grade A-572 steels and other alloyed steels are being used in structural applications, these steels are heat sensitive, thus using weave beads can cause problems with failures in the HAZ zone, the parent metal can be relatively unaffected, the weld metal can be relatively unaffected, but the zone where the two meet can have the alloying elements burned out by the elevated temperatures that are present by using excessively wide weave beads and trying to carry too much weld metal. The other thing that I heard in these posts had to do with electrode manupilation, my experience with E7018 electrode is that it needs to be run with a fairly short arc length and that any sort of electrode motion needs to be smooth and definitely not include any sort of whipping such as that that would be used with E6010 or E6011 electrodes. I'm sure others will have different opinions, this is just my 2 cents worth. aevald
I'm going to go out on a limb here and presume that the qualifing code is AWS and that the WPS is prequalified. That being said, your weld size (stringer or weave width with no real distiction) would be restricted to the requirements of table 3.7, as is rod diameter to position and bead/weave width to depth ratios.
Maximum rod diameter for limited or unlimited thickness in both 3/4G tests is set at 5/32" for loHy, the root pass is subject to the W/D ratio of 1/2" (hard to do with 5/32") for vert's and 5/16" for OH. Maximum fill would be 3/16", 1/4" for wire. So, the way I see it, a weave of 1/4" to 5/16" is acceptable (to me anyhow), and works out to roughly 2x nominal rod dia. But these big ass wash passes and caps of stringers that look like butt cheeks, are illegal, immoral and down right discusting. Wayne
waynekoe - your missing post ended up on the next topic
Thanks Jerry, Ain't technology grand.