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Up Topic Welding Industry / General Welding Discussion / Cope cracking again....
- - By jwright650 (*****) Date 01-15-2009 19:08
Anyone else have these same problems?

I find that 90% are not visible with the naked eye, but after inspecting with MT a 2" or longer crack appears. This last truck that we just unloaded had 18 beams of various sizes to be repaired. I have 3 more trucks due to arrive back from the galvanizer sometime today....oh boy, I can't wait.....

Just venting.....
Parent - - By aevald (*****) Date 01-15-2009 20:22
Hello John, haven't seen a lot of this sort of thing. A couple of questions though: are these crack issues limited to a particular grade of beam (A572, A36, etc.), do they come from a particular manufacturer as opposed to various ones? Asking this set of questions with the possibility of having some materials process issues (internal stresses, metallurgical differences, chemical issues: carbon content and related type things). Are the fabricators making any weld repairs of their copes afterwards to allow for errors with the initial cuts? When they are grinding them and cleaning them up after cutting are they having excessive notching due to direction or technique used to perform the grinding? Are the cope radiuses of sufficient size and shape to allow for proper stress distribution?
     This topic has come up before and I am sure that you are aware of all of the items that I have mentioned, yet maybe you haven't addressed the particular one that might apply in this case. The galvanizing process certainly aggravates this sort of thing due to the variance in rate of heating and cooling that could occur with the process and the difference in mass between the beam and the surface coating of the galvanizing. Sharing your pain John, best regards, Allan
Parent - - By MICHAEL B (*) Date 01-15-2009 20:37 Edited 01-15-2009 20:45
John,
We had this problem in the past. What we ended up doing, and still do, is weld around the radius of the cope, before we send to the galvanizer, with a 7018 on both sides of the web. This has eliminated the problem, and we let the estimating department add the extra cost in for these type jobs. Hope this helps.

MICHAEL B
Parent - By TozziWelding (**) Date 01-15-2009 22:22
We started to do that on certian Grade50 beams as a PM.
Parent - By jwright650 (*****) Date 01-16-2009 02:35
We have done that in the past, but have since gotten away fom it because we went several years without anymore problems....but it seems to be back. If you look up galvanizing or cope cracks you will probably find all of the threads where I had trouble before.
Parent - - By BryonLewis (****) Date 01-15-2009 20:48
Got pictures?
Parent - - By jwright650 (*****) Date 01-15-2009 21:54
No pics...I didn't have time, we are rushing to get them repaired and back on the truck. No particular pattern with this batch, other than they all came from the same  galvanizer...several different material suppliers, all A572 gr 50, all different sizes, no real pattern to the notice in the cuts of the copes, there was only one cope that I would have been suspicious of in that it wasn't rough, but too sharp of a radius for my liking, the rest are all nice copes. I'll try to get pics if the next few trucks come in and we find the same problem. I have pics of previous problems like this, but none from this round of repairs.
Parent - - By hogan (****) Date 01-15-2009 23:00
Sounds more like an issue in making the cope rather than the material, if they are all looking as they should.
Parent - - By jwright650 (*****) Date 01-16-2009 02:36
These are pretty copes, with the exception of the one that didn't have enough radius in it.
Parent - By ctacker (****) Date 01-16-2009 03:02
last place I worked we were required to drill all radius in the copes before putting the torch to them, took care of a lot of issues in regards to cracking and having the right radius.
Parent - - By jwright650 (*****) Date 01-16-2009 13:42
OK...I snapped a couple pics really quick. I found a couple more beams this morning.
I still have more trucks coming, so I don't know what to expect with those.
Here are the pics.

typical sample of coped out beams....


in progress of gouging out the crack....


MT indications showing cracks in copes.....


another MT pic of cope in another beam....
Parent - - By BryonLewis (****) Date 01-16-2009 13:55
Thanks for the pics.  It makes more sense to me now.  I was having a bit of a time visualizing the problem.  Good luck with that.
Parent - - By jwright650 (*****) Date 01-16-2009 13:58
These are small cracks that needed MT to even discover them....I had some yesterday that you had no problem seeing them with the naked eye(they were 2.5" long and very noticible)
Parent - By swnorris (****) Date 01-16-2009 17:48
John,

We've had success by grinding copes slick with a flap disc after the usual grinding.
Parent - - By CHGuilford (****) Date 01-16-2009 17:50
John,
Since this issue had come up previously, we have been seeing some projects with a requirement to weld a bead along the radius on both sides of the web.
Not all jobs require that, and naturally if that wasn't in the bid, we are not told to do so.  As you know, some copes crack and some don't and no one seems to have the definitive answer. 

It could be that the welding anneals the steel, or the extra material resists stress better, or the chemical composition might be changed enough, or maybe a combination of all three.  But, so far, of the beams that I have seen welded that way none have cracked in the copes after galvanizing.

One thing more - I also haven't seen a problem with copes that were made by drilling the hole for the radius.  We do that wtih our drill-line whenever the cope is deep enough to allow for it.
Parent - - By jwright650 (*****) Date 01-16-2009 19:25
Chet we have talked in the past about this and my assumptions are still the same. Check your PMs, I'd rather not repeat that in the open forum because it is only an assumption.
Parent - By ctacker (****) Date 01-17-2009 03:48
Aww, come on JW, some of us would like to hear your assumptions.
Parent - By DaveBoyer (*****) Date 01-17-2009 04:04
   What % elongagation does this material have? Material with much elongagation isn't generally extremely  notch sensitive. I have to wonder if there is localized hardening from the flame cutting that is not being removed by grinding. Drilling the radius or welding at the cut edges being a solution would tend to support this idea.
Parent - By ibeweldingsum (***) Date 01-16-2009 18:35
Looks to me like stresses from welding and small striations forming from the grinding. I would try smoothing the radiuses prior to galvinization
Parent - - By darren (***) Date 01-17-2009 05:59
as a control group perhaps make the same cope in different spots throughout a web and see whether it still cracks. just a wild guess here but the copes proximity to the web flange interface could be the problem there are a lot of inherent stresses in that area, as well the larger heat sink created by the web flange interface area causing disproportional contraction in the cope also the rigidity of the web flange interface will not allow for equal distribution of the contracting forces. you know alot more about this than me so i am really just thinking out loud.
darren
Parent - - By Bob Garner (***) Date 01-19-2009 23:46
Well, as a structural engineer that designs lots of coped beams, this troubles me big time.  We (engrs) are taught that the surface finish of radii at copes is important to be ground smooth.  The surface finish in the photos looks a little rough but it's a tough judgement call.  I hope to have time to present this to the AISC Steel Solutions people tomorrow - is this just happening on galvanized materials?  Meanwhile, I will chase around the threads presented.  I'm flumoxed on this one right now.  And worried!

Bob Garner
Parent - - By jwright650 (*****) Date 01-20-2009 12:25
Bob,
I would be more concerned if we didn't bring all of our galvanized materials back to the shop for a good looking over, this gives me a chance to catch stuff like this plus straighten any distortion that happens during this process(spandrel frames especially). Some fabricators send their materials straight to the job to be hung out with the hope that the galvanizer's people catch any problems that might arise while they have it. I have never seen any copes cracking until "after" galvanizing in my 25 years with this company. We only started noticing this a few years ago, I had heard stories, but never seen anything until I received I whole truck load of beams back that had problems, so now I inspect it pretty good to make sure things are OK before it gets shipped to the job.
Parent - By Bob Garner (***) Date 01-20-2009 15:26
John, and everybody,

I truly appreciate this forum.  Ya think after a gazillion years of experience that you have a pretty good handle on your work - NOT!  After some discussions with other engineers in our office, our consensus is that we will do more post-galvanizing inspection.  We used to look at the steel "from a distance" for major distortion or constructability issues.  But for now, our directive is to look closer.  We're considereing additional testing for cope cracks.  Does anybody else do any specific testing in the coped areas of beams just for this reason?

We're still researching the stresses inherent in the "k" areas - it seems that this could be a cause, too.

I appreciate this discussion.  Thanks.

Bob Garner
Parent - - By jwright650 (*****) Date 01-20-2009 12:33
BTW, I'm curious, which picture are you talking about in regards to the excessive surface roughness? I think what you might be seeing is the coating...this stuff is hot dipped so it isn't exactly smooth when it hardens as it drips off when it comes up and out of the bath. Be careful handling galvanized steel because there are some very sharp icicle looking burrs of built up zinc that hang off the bottom ends where the coating has hardened as it drips after the dip....these "iciles" can puncture a leather glove rather easily.
Parent - - By Bob Garner (***) Date 01-20-2009 21:10
Hi John,

The photos show the edges but not the surfaces of the cope cuts, so all I can see is the galv. coating roughness as you noted (I think they call that dross?) 

Bob
Parent - - By Bob Garner (***) Date 01-21-2009 14:58
Good morning, everyone (We're just getting our sunrise over here in Sandy Eggo).  I did some literature research on cope cracking and I am putting a pdf file together of the stuff I found.  An article in the 1995 issue of Modern Steel Construction seems the most authoritative and I will include that.  I have info requests in to AISC and the Hot Dip Galvanizers Association but they have not responded yet.  I will attempt to post my pdf file here in a little while (after my morning coffee).

I checked with the old geezer structural engineers here in my office and they were aware of cope cracking.  They said long ago, they used to prevent flame cutting of copes for that reason but that requirement just sort of died out.  Of course there's more to the issue than just the flame cutting.

Be back soon.

Bob Garner
Parent - - By Bob Garner (***) Date 01-21-2009 16:09
O.K., here is my attempt to attach the pdf file of the literature I found on cope cracking.  I do not have permission from Langill and Schlafly to print their article but I have reproduced it here for educational purposes.  Also, I do not represent my firm, Moffatt & Nichol Engineers in posting this material, but I post this material as an individual structural engineer for the purposes of increasing the knowledge base of all persons working in the construction industry (sorry for the legal disclaimers).

Bob Garner
Parent - By jwright650 (*****) Date 01-21-2009 16:27
Bob I also have a folder chocked full of articles that I could share with you on this subject, but I don't have permission to publish them here for all to see. Contact me via PM if you are interested in reading any of this material. BTW, Some of it was by Thomas Langhill, and others at the galvanizing association. Langhill stated in one of his articles that the smoothness and radii of the copes had very little effect on whether the copes cracked during galvanizing or not. He contributed the cracking to be more frequently associated with the flame cut itself.
Parent - By welderbrent (*****) Date 01-21-2009 16:36 Edited 01-21-2009 17:04
Bob,  I don't see your pdf attachment.

BTW, a shop I am doing some inspecting at currently uses small detail belt sanders with the proper sized mandrel for the radius desired to clean their copes after torch cut.  Works very nicely and leaves any sanding marks going with the web instead of transverse to the web. Reduces even more of the notch effect for stresses.

Have a Great Day,  Brent

Just in case my observations are misunderstood by anyone, I am not suggesting that this type of grinding would stop this particular cope crack problem.  That seems a rather odd situation to me.  Don't understand how just galvanizing would bring out so many cracks when there are really no stresses on the piece.  There are, however, rapid temp changes that, depending upon the original composition of the beam, could contribute to this.  Anyway, good luck finding a solution.  I am eagerly waiting to see if an answer presents itself with all the great resources at work here.

Again, Have a Great Day,  Brent
Parent - By BryonLewis (****) Date 01-21-2009 17:09
Thats quite a mouth full.
Parent - - By Bob Garner (***) Date 01-21-2009 17:51
John and everyone, thank you for your references.

Apparantly, my pdf file was too large to post (1.39MB).  I can send it directly to you if you send your e-mail address to me at  rgarner@moffattnichol.com

I would also appreciate anyone sending me info on this subject, too.

Thanks again.

Bob
Parent - - By jwright650 (*****) Date 01-21-2009 18:34
Bob,
I'm in the middle of an AISC audit today, but I will try to get in touch with you at a later date and see which of the articles you may be interested in reading.
Parent - - By Bob Garner (***) Date 01-21-2009 18:41
Let me see if I can "game the system" and send these as three separate files.  Here's the first.

Bob
Attachment: CopeCracking2.pdf (844k)
Attachment: CopeCracking3.pdf (716k)
Attachment: CopeCracking1A.pdf (809k)
Attachment: CopeCracking1B.pdf (801k)
Parent - - By BryonLewis (****) Date 01-21-2009 19:11
Bob and others,
I have even less clue than you fine experienced gents.  But whilst studying for the CWI exam I am reading cover to cover D1.1:2008.  I have been reading these posts on the cope cracks and I have found something in the Commentary of D1.1 that I would like to see if it might help the cracking.

Figure C-5.2 shows three "Examples of Good Practice for Cutting Copes".  My inexperienced, yet inquisitive eye, found this figure and would like to know if any of you guys have any thoughts on the possiblility of this being a "solution"?  I read through some of your articles and it is very intriguing to me.  I wish I had more answers and less questions, but what are you gonna do.
Thanks
Parent - - By jwright650 (*****) Date 01-21-2009 19:20
Hi Byron,
The AISC has that detail in their manual of steel construction and it has been there for a number of years now. I don't remember who had that detail first(AISC or AWS), but it doesn't matter, the idea is to place the notch (from the tip of the flame) in the material that will be discarded once the cope is cut out. That is just good practice regardless of whether the beam will be galvanized or not.
Parent - By BryonLewis (****) Date 01-21-2009 19:29
Ok!
Up Topic Welding Industry / General Welding Discussion / Cope cracking again....

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