i have a large plate girder splice , with a gap between the backing bar and the under side of the top flange of 3/16" is there an allowable and acceptable fix for this ,cutting this girder is out of the question ,the bottom flange fit is tight no gap there, the flang is 4" thick X 2' wide girder is 56" dep box type ,this splice will be subject to UT inspection
any suggestions
Will the backing bar remain in place after welding?
yes the backing bar will remain after welding
Like Joe pointed out, this isn't an easy fix. My suggestion would be like Joe's and to bite the bullet and after welding the joint out, go back and remove the backing bar and clean the root to sound material, then re-weld. I think this would take all of the weird configurations and signals out for the UT guy to try to interepret. This would also eliminate the notch potential where the backing bar has a gap.
This may not be what you wanted to hear, because it will add cost to remove, back gouge and re-weld. Best wishes. Keep us informed on how this plays out. I'm always curious how these weird field connections in the field get worked out. All I get to see is the fabrication shop side of these issues.
billk63
Nicely presented with a nice picture! A drawing showing the girder configuration and the rest of the joint might also be helpful.
As you imply, if this joint is welded "as is", you will not be in compliance with the Code (presuming it is the AWS D 1.1 or D 1.5 code). Thus it will require a specially qualified, and "engineer approved" UT procedure to properly evaluate the completed weld joint. The "Pre-qualified" (my description) techniques and the acceptance criteria specified in Clause Six will not apply. You may have to back gouge and remove the backing bar, then re-weld. Finally you will have to grind the proper 12 to 1 slope in the back welded joint.
I NEVER trust the UT techs to properly perform and properly interpret UT evaluations on these irregular joints. In addition, if the special (Annex "K" in the older editions, or Annex "N" in the 2010 Code) UT technique is used, It will not only have to be developed and then approved by the engineer, but the engineer will also have to specify the acceptance criteria. There may be only a handful of structural PEs in the world who can actually perform this function properly.
As always when these anomalies occur, I advise that the problem should be presented to the Engineer of Record with the proper code references and diagrams and pictures and get his input. My guess is that the engineer will just wing it and let it go as is. Then it all falls on his head! CYA!!!!!!
Joe Kane
Hello billk63, this might be a bit of a stretch, but could you machine an offset into the backing bar and possibly address the misalignment in that manner? Just a thought. Best regards, Allan
billk63,
Can you pad weld/butter/overlay with weld metal to the proper 12/1 slope prior to backer bar placement. Since 5.22.3 gives an 1/8" misalignment, then you would only have to deposit a "heavy" 1/16" with a minimal amount of work. Save a lot of gouging and cleaning later????? Or wait 2 weeks for the RFI....
Typo...1/2 inch in 12 inches... instead of the 12/1.
No matter what type of temporary backing is used, there is still the non-compliant 3/16" butt joint alignment mis-match.
Since backer bar removal is not required, my suggestion might provide the most expedient (user friendly?) solution.
AND I don't think it says anywhere in the code that this welded transition must be finished any smoother other than acceptable weld profiles.
If I read the OP correctly, this joint is 2 feet wide, the machinist will need to measure precisely to get a good fit for the entire length of the joint. I thought about sloping the backing bar between the two 4" thick pieces but that also creates an unacceptable joint that will leave a notch.
Buttering as suggested may be something that is viable, albeit overhead welding will be involved whether the bar is removed and back gouged or if buttered before welding.
Understand John, I believe Superflux may have the best alternative if that is deemed acceptable. I should have read the original post a bit more closely instead of skimming. Thanks for pointing that out. Best regards, Allan
Hello again billk63, one other possibility here, hopefully I haven't missed any other details of this issue. Is there any consideration for using ceramic backing? Likely requalification for the joint and possibility requalification for your welder? Yet a possibility? A stretch, I know, but alternatives are alternatives. Best regards, Allan
Several people have mentioned the issue of the alignment of the two members. I am not adding anything new, but simply adding my support that the joint does not meet the alignment criteria of AWS D1.1 (assuming this is not a bridge). This issue and the corrective action required must be determined by the Engineer.
Several possible corrective actions have been suggested, but since the misalignment exceeds the limitations prescribed by D1.1 the Engineer's involvement is required per clause 5.22.3 (using D1.1-2008 as a reference). The contractor and the welder are overstepping their authority to attempt to take corrective action without the Engineer's blessing.
The issue is not one of simply making the backing "fit" or whether the welder can simply weld the butt joint and then blend it in to form a smooth transition from one member to the next. The issue is whether the offset will result in sufficient eccentricity to cause the nature of the load transfer from one member to the next to become a problem, i.e., bending moments in the flange or elsewhere.
The Engineer is paid by the Owner to address these types of problems. Few contractors have the engineering background or experience necessary to design a proper “fix” for this type a problem. Let the Engineer do his job.
If you broke your leg on the job site, would you want the foreman or the supervisor to set it just because they saw how it was done on a TV show or would you want a doctor with the proper training to take care of it?
Best regards - Al
Hello Al, I guess I often can't see the forrest for the trees, thanks for reminding me. Since that is the first issue of consideration, that should probably be what drives any other options for dealing with the situation. I'll sit back for now and see where this goes. Thanks and best regards, Allan
billk63
I hope you can keep us informed as to the resolution to this problem. Please tell us what code is in play here.
This post has stirred my interest, not just because you laid it out so elegantly. I have had to address it three years ago on a canted splice for the Freedom Tower sub-grade steel columns (W14x730, GR-65). The Engineer simply bought off on it, and I was given no other information. It was particularly galling to me. because I advised the contractor to check the center line of the web, before making the splices and be sure that the piece was cut so that the web remained in the same plane. I told them that the web was not centered. This is lay-out 101 for anyone who has done lay out and fit-up before.
Joe Kane
alot ways to fix this.
old school is a rosebud and water, in other words bend one to fit.
a rosebud and come-along works great if you got something to latch it to
you also have clamps and welding to get it close, clamps you need big men.
also depends on where you are doing this?
you on the ground? in the air hanging iron?
just some thoughts from an old timer
thank you for your time and consideration
sincerely,
Kent
I have run across this before also, The EOR let us use it as (similar to)a corner joint, where you slide the backing bar till it buts up to the lowest side, you could grind a land on the lower side and butt the BU bar to that.
I attached a crude sketch to give you an Idea.
i thank every one who who has responded to my post
this is where we are at today with this issue,
we have discovered that there is some flange tilt involved that may be causing this condition,this girder was shop assembled and all fit well ,the girder is 80' long when assembled,and sets on bearing pads,there may be a roll in girder caused by un level bearing pads or the flange tilt,we plan to check if there isa roll at the bearing pads ,than we may have to heat straighten the flange tilt near the weld joint
i will let you know the results
thank you all for your help
THE END RESULTS
we were able to align the top and bottom flanges by moving the girders ,the webs were a different story ,they were 1 inch thick plate ,we had a gap at the backing bar on one side ranging from 1/4" to 1 /16" over 5' ,also miss alignment between the joining plates of over 1/4" we had some calculations run by our engineer and came up with that we only need a 3/4" partial pen weld to meet the requirements of the joint ,so we ran a root at the miss alignment ,filled the joint and finished off per D1.1
thank you for all you help
bill k
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