i agree with you hogan in that the flux ball needs to come off completely, not only as a code requirement, but i learned that the hard way about ten years back when i was GMAWing some (alot) of studs..... i was new to it and the foreman cut me loose after he checked out my settings, but didn't bother to tell me the flux ball had to be removed, i didn't know any better until i started getting about a 3/32 size hole at the point of my start and terminate point of the weld where the flux ball kinda "squirted out" and the weld pool froze. needless to say i had some repairing to do! i've never made that mistake again.
JJ
With all due respect to everyone, right or wrong, I've never flattened a flux ball. I've never had any problems, and in my experience I never really saw the need for it. Everybody seems to be concerned that the stud base fits against the base metal, so everybody wants to flatten the flux ball. I guess this is somehow taken from 7.5.5.3 Stud Fit (Fillet Welds). "For fillet welds, the stud base shall be prepared so that the base of the stud fits against the base metal". I don't think this really applies so much for studs manually welded in the flat position, but more so for studs that are manually welded at a 45 degree angle to the heel of say, an angle (L3 x 3 x 1/4) or at a 45 degree angle to the inside "fillet" of an angle. It seems to me that 7.5.5.3 would apply more to the latter two applications, because in order for the 45 degree angled stud to fit against the base metal at the heel of the angle, technically, a 90 degree vee would have to be ground into the stud base so that the stud base would fit against the angle heel. For a stud to fit at a 45 degree angle on the inside "fillet" of an angle, the stud base would have to be radiused, or rounded, so that it fits against the angle fillet.
For those who are not aware, the 7.5.5.3 paragraph has been relaxed over the years. In the '80 version of the code, it stated that the stud base shall be prepared so that the outside circumference of the stud fits tightly against the base metal. To me, there was no question about what needed to be done, especially with the word "tightly" being used. With everyone being concerned these days with the stud base fitting against the base metal, nothing should be allowed for fit up tolerance when the studs are tacked. If the stud is not fit and tacked at a perfect 90 degree angle, then the stud base is not fitting against the base metal, and therefore rejectable. We have tolerances for everything. We fit and weld things every day that have a 1/16" gap, or more. I just think that flattening a flux ball that is no more than 1/16" long on every stud that is manually welded is overkill, and going back to the 45 degree angled stud that fits inside an angle, if those are manually welded, do you flatten the flux ball on it too? In that situation, the flux ball isn't even a factor because the outside circumference of the stud base is the only thing to come into contact with the inside fillet of the angle, and furthermore, only two very small portions of that circumference are in contact with the base metal.
swnorris,
Respectfully, of course, I do not interpret it that way.
"For fillet welds, the stud base shall be prepared so that the base of the stud fits against the base metal".
I read that to mean, regardless of angle of stud, or welding position, the base must fit flat against the base metal. No matter which angle or position.
Please allow me to request a diagram showing what you are describing, as I may very well have missed what you meant.
Thanks,
John
John,
Please send me your email address and I'll scan a sketch and send it to you. To me, there is essentially no preparation needed at the base of the stud, for the flat application, but the "shall be prepared" really kicks in when the stud is welded to the heel or to the inside of an angle. I'm going home now, but I'll draw it up and send it to you in the morning. If you don't want your email published, just send me a blank email and I'll reply. I assume you can open tif or pdf files?
Thanks
I will PM you.
Thank you,
John
swnorris,
Thank you so much for taking the time to help me understand. After reviewing the sketch you e-mailed me I would say that this is a spot on interpretation of the mentioned code referance. Also I would like to thank you for allowing me to attach the sketch.
Best regards,
John
Attachment Compliments of swnorris:
The GMAW although listed in section seven as prequalified along with SMAW and FCAW. The code does not allow GMAW-S as a prequalified process and GMAW-S is usually treated as a separate process because of this. Upon review of procedure that was provided several things were obviously in error. The form used was a stud welding qualification form and a GMAW-S was used which should have been in adherence to section four. What protocol should have been followed. The studs had been on project for 6 months and proper receiving ionspection had not been performed. The procedures were in error. A questionable process was used. All welds did not meet the 1/4 inch requirement for size. Questions DO you try to salvage anything on this one? Reject the whole lot. Proceed with resolve. How do you ascertain any credibility of existing welds that were done with questionable procedures and substandard work. Code does not require the bending of studs done with prequalified processes.. This one got out the door and on site without any scrutiny.
If you're the inspector, there's only one thing you can do. Reject them based on the code violations you've mentioned, submit the report to the EOR, and let he/she make the decision on what to do. It may be salvageable. If I were that person, I'd require the same GMAW-S process used to be sucessfully qualified by PQR and, along with the WPS and welder qualifications, require all to be witnessed by a third party. Next, the existing fillet welds should all be close to the same size. The fillet sizes or a percentage of the sizes could be verified and the EOR could run calcs. to determine whether they may still meet design criteria. Lastly, I'd require the bend testing of a percentage of the welded studs that have been bent at a minimum of a 45 degree angle, or bent all the way flat. It would also depend on the design intent of the studs. If they're general purpose studs, that's one thing,, but if they're used to transfer shear in composite beam design, that's quite another. I'm not an engineer by any stretch of the imagination, but that's my take on it.
Scott one more thing to consider with fillet welding the stud particulary on flat plate....with the flux ball ground off or flattened with a hammer the stud sits flush on the plate, without prepping the the flux ball the stud stands off of the plate by a 16th or so....now if you run a proper sized fillet weld around the stud as required, which one will give you better penetration into the joint between the stud and the plate?
Exactly. I agree that the 1/16" gap gives better penetration. We weld other things pretty much daily that have 1/16" gaps, and there's no problem with that. I just don't see the point of removing the point, ya know? Also, by leaving the flux ball, the fillet weld size needs to be increased so that the proper amount is on the stud. That's not causing any extra labor on the welder, because typically, if a 1/4" fillet is required, the welds usuially end up 5/16" anyway.
So is there no concern with mixing the stud flux into the GMAW weld ? From what I've observed the flux stays segregated in the GMAW pool, at least the majority. As mentioned previously, this will usually happen at the stop start.
By swnorris 
Date 05-21-2008 14:17
Edited 05-21-2008 14:20
hogan,
I just don't see how it can be mixed. If you're fillet welding , say, a 3/4" dia. stud on a flat plate, you'd have to penetrate 3/8" deep into that stud in order for the weld to reach the center of the stud, where the flux ball is located. If you're burning that hot, I'd think that you'd undercut the stud and the base metal, and probably be way beyond the wire manufacturers recommended settings and your WPS. Maybe you guys are experiencing the mixing issue because you're welding small diameter studs, such as 1/4"? We typically weld either 1/2" dia, 5/8" dia., or 3/4" dia.
Thank you Scott Norris for the assistance.
I turned this over to the EOR 30 minutes after I discovered it. I was asked to proceed with a repair procedure much like you described. I alerted the EOR that he was proceeding at risk until someone actually approved the temp resolve while waiting for sub to submit proper procedures. for the repair of the defective stud welds. I randomly bent a percentage of studs to determine if existing welds deficient as they were had any effective strength. Then the areas of the undersized welds that had cold lap were ground so it could accept additional weld material allow it to meet the size of weld dictated by section seven .
I find it discouraging at times to know that what you are asked to do is at times not the proper way to proceed for the best end product. Schedule is an issue but quality seemingly is not the issue until something happens that cost someone big money and schedule. I had to listen to complaints like I should change my attitude towards subcontractors. I replied that if the contract is written correctly and the specifications are there then they should be met (no excuses) You should get what you are paying for.
I have not used a pipe to bend studs but sounds like a good idea. I initially found this problem thru sight but found defective studs with the hammer. I might go to Alaska to go fishing.not to bend any studs.
I,m going to attempt this again, my computer skills are less than desireable today.
In answer to your first question, as to going through the procedure process, is that first, it has to be done for any process used, and secondly, there are just too many holes in the use of the GMAW process needing verification. Wire types, gas types , gas mixtures, making sure the guy thats doing the welding knows the difference between short circut and spray, enviroment, ect, ect. Its just not a standard, practical method for the application of shear studs. In all the years that I've been involved in welding, I can't recall that GMAW has been used. I'm not saying that it doesn't happen, I just saying that I've never seen it (I think). The flux material, I don't believe, is going to have any apparernt effect on the weld quality. If it was detrimental to the final outcome of weld quality, I don't believe it would be there in the first place, its a dolup of aluminium (i.e. a suitable deoxidizing and arc stabilizing flux) which is highly conductive and I feel that its purpose is to insure a good, clean arc start. If I'm wrong, please correct me. As far as the beat down of the flux ball, I cant find any thing in sections from 7.5.5 thru 7.5.5.6 that actually says that the flux ball has to be completely removed, but if you feel more comfortable,, hit with a grinder; 7.5.5.1 says that the surfaces shall be free from foreign materials producing objectionable fumes; 7.5.5.2 says for fillet welds, the stud ends shall be clean; 7.5.5.3 wants the stud base to fit flat against the base metal, so with a couple of good whacks, I am pretty much assurred its less than 1/16", and then it goes on to fillet size, SMAW rod size, and finally on to inspection. Thereby, no need for the flux, period.
For inspecting studs, shot down or fillet welded, I use a 5' long piece of 1 1/4" sch. 80. I don't feel that a hammer test is an adaquet method for testing stud welds, particularly here in Alaska. While section 7.8 sets bending limits, 7.8.1 & 7.8.2 gives me a pretty wide berth for inspection, and regardless of how they're applied that stud should bend 90 degrees
When the trigger is pulled, a pilot arc is started. The pilot arc burns the aluminum flux ball, which purges oxygen out of the cavity inside the ferrule, creating an oxygen free environment for the weld, which prevents contamination. Once the flux ball is burnt, the main arc starts and creates the weld.
And god created the heavens and the earth in six days. Let me start with Hogan. Yes it is a prequalified procedure, I never said it wasn't but, as with all AWS crap, it has to be written down, and is subject to all the pertaining essential veriables prefferably in four different languages so theres no chance someone could misinterpret the instructions. You'll have to show (tell) me where it says that it has to come off completely, but given two whacks with a beater, I don't believe you'll have much more than a 32nd of an inch to contend with. I'll go out on a limb here, because I don't have a stud in front of me right now, but i figure the ball hight to be maybe an 1/8" or slightly smaller, leaving the ball at its production hight wuold mean your minimum weld size would have to increase by that much, paragraph 7.5.5.3 would mean nothing, and that Scott has a lot of studs that are out of procedure. I'll continue this tomorrow- My best to all !!!!
"In answer to your first question, as to going through the procedure process, is that first, it has to be done for any process used, and secondly, there are just too many holes in the use of the GMAW process needing verification. Wire types, gas types , gas mixtures, making sure the guy thats doing the welding knows the difference between short circut and spray, enviroment, ect, ect. Its just not a standard, practical method for the application of shear studs."
If it's not standard then why is it a pre approved process for welding studs and other structural steel (if we are following section 7 i assume were following all other sections)? Just because your not familiar with it. We never use stick. Only FCAW or GMAW
"I'm not saying that it doesn't happen, I just saying that I've never seen it (I think)."
"The flux material, I don't believe, is going to have any apparent effect on the weld quality."
do you have a reference for this? I would need more than someones word on this.
i will perform the hammer test on all studs made with the stud gun and the bend tests. I have found that it finds bad studs that look fine. On a side note, why in particular do you not want to perform the hammer test in Alaska?
hogan,
I agree about not taking someone's word. I guess you could do a macroetch sample on a manually welded stud to see for yourself, but as I said, there's no way that a fillet weld will penetrate halfway through a 1/2" or 3/4" dia. stud to even reach the flux ball, unless the welder is burning way, way too hot. If that's the case, there would be issues with undercutting the stud and probably the base metal, and issues with the WPS as well.
waynekoe,
In my 2nd response, I stated that the flux ball is no more than 1/16". That was based on eyeballing it. After your last post, I verified with a caliper that the flux ball is 1/16" on a 3/4" dia. stud, and slightly less an a 1/2" dia. stud.
In my 5th response, I stated that the weld size would have to be increased to account for this gap.
Also, guys, what about the attached sketch previously posted by jrw159 on my behalf about "preparing the stud base so that it fits against the base metal"? I'd like to hear your comments about that. Seems to me that this would be a much bigger issue with stud/base metal contact than removing a 1/16" flux ball. Please take a look.
Scott, i seem to remember there was a previous post about prepping the stud. This is something that is the norm around here. I think that there was someone that could not believe i was requiring this. So i agree with your interpretation. From what i have seen the flux will melt when manually welding a stud following a reproved wps. I was thinking about the flux ball issue and wondering if a ball of AL would be considered acceptable in any other joint?
hogan,
Absolutely not, but how do you know that it ends up being mixed in the weld pool on a flat plate?...... and at the same time, how do I know that it isn't, right? The melting point of steel is twice that of aluminum, and when melted, that tiny melted aluminum flux ball surely has to go somewhere. You've swayed my thinking a bit, but I'm still not sure that it contaminates the fillet weld. I guess the only way to really know this is through testing. I can't deny that the flux ball gets melted, but have you determined that it ends up in the weld pool? If so, how did you do it? The flux ball is just so tiny, it seems so insignificant, you know? I've fillet welded studs in the past, allowed them to cool, and bent them all the way over until the stud head is touching the base metal, and there was nothing wrong with any of the welds. Also, that was probably me on the previous post you're referring to.
Edit:
Food for thought..... why wouldn't the flux ball cause problems within the weld metal on a stud that is automatically shot?
Scott, i have no idea if the AL is actually melted into the fillet weld. I would consider it a potential weld metal contaminate and feel justified by the code to request it be removed.
Food for thought..... why wouldn't the flux ball cause problems within the weld metal on a stud that is automatically shot?
What would happen if you added SAW flux to a FCAW weld?
Guys, when you shoot a stud, you get a full pen weld....welding manually you should place a fillet weld large enough to be as strong as the full pen...that's where the table comes in giving the min siz fillets for each diameter of studs.
I guess my question is....So what difference does it make about the fluxball as long as you obtain the same strength which is proven(qualified) on your first few studs by testing? Each production run of studs, whether shot or manually welded, have to be qualified.
the flux actually expells out just when you reach your stopping point, (GMAW) that is what i have actually seen under the hood. even with the hole that was produced from this all the studs bent just fine, however they were repaired because we were'nt gonna ship out studs with a hole in the fillet weld.... ( stud gun application) the flux ball (aluminum) is forced out of the weld pool when the stud gun plunges down at the end of the cycle and escapes through the ridges at the bottom of the ferrule along with weld spatter. that's my understanding of what happens. let me know if you see it differently.
JJ
Hogan, I have a few answers for you! I don't think that you'll find any place in my post saying GMAW welded studs is not legitimate. I said that they are, or at least would be. All welds have to have the required WPS, and, I believe that you're aware of that.
Penetration, cementation, you're making fillet welds here, remember? And just how deep does the penetration on a fillet weld have to extend. If you leave the flux ball in there, you've just created a partial pen weld with a foreign inclusion. And if any of that stumps you, you can read 7.7.1.4--Wayne
Wayne,
(fourth post)"I don't think that you'll find any place in my post saying GMAW welded studs is not legitimate"
(second post)"In answer to your first question, as to going through the procedure process, is that first, it has to be done for any process used, and secondly, there are just too many holes in the use of the GMAW process needing verification. Wire types, gas types , gas mixtures, making sure the guy thats doing the welding knows the difference between short circut and spray, enviroment, ect, ect. Its just not a standard, practical method for the application of shear studs"
"Penetration, cementation, you're making fillet welds here, remember? And just how deep does the penetration on a fillet weld have to extend. If you leave the flux ball in there, you've just created a partial pen weld with a foreign inclusion. And if any of that stumps you, you can read 7.7.1.4--Wayne"
you lost me on the above statement.
I was still wondering why no hammer tests in Alaska in particular? And enough with the condescending crap. It make you look silly.
section 7.7.1.4-as you so like to quote, look about 2/3 down the the papagraph to the part that starts with "At tempertures below 50 degrees", and I didn't say everyone in Alaska, I said I don't! And I don't feel a bit silly about doing it that way.I also thought that you would catch up on the fact that a fillet weld only has to the root of the weld and not necessarily beyond, leaving the flux ball on gives you what some people might call a root opening, ergo, a partial pen weld with this big chunk of freakin aluminum in the middle of it! 7.5.5.3 tells you that the stud base, "For fillet welds, the stud base shall be prepared so that the base of the stud fits against the base metal".
As for my remark about GMAW, I only said it was unconventional, primarily because most shops, heres the important part, "THAT I KNOW OF", if their not using a gun, then it's dual shield, but, since 90% of my work is in the field, the use of either FCAW-G or GMAW is pretty much out of the question, unless you live in some part of the world where the wind never blows.
When I walk into a shop for inspections, the things I'm asking for are certs and procedures, so if the shop is using a GMAW procedure that says 100% CO2. then thats what I want to see in the bottle rack on the machine, not a 75/25. The same goes for FCAW-G.--I,m not stumpted at at all. In fact,quite the oppsite, and I'm not being condescending, but, if your going to ask sarcastic questions, you'll get the same kind of answer, thats just my nature.-I'm not trying to show to everyone that know everything-cause I don't know jack compared to a lot of people who post here, and am learning all the time. I also hope that you and I can keep having these delightful discissions without getting pissy with each. This is just how I do business.
