American Welding Society Forum
126.96.36.199 Correction. Root openings greater than
those allowed in 188.8.131.52, but not greater than twice the
thickness of the thinner part or 3/4 in. [20 mm], whichever
is less, may be corrected by welding to acceptable
dimensions prior to joining the parts by welding.
Aside from buttering/ surfacing / build-up, what other possible method of repair welding that you think may be applicable to the above para?
Thanks & Happy New Year!
Off the top of my head I can't think of another option. The only thing I thought is that the next paragraph requires engineer approval for correcting a root opening that exceeds anything greater than those allowed by 184.108.40.206
Here is an extreme example to show another possibility: Job I'm currently working, the shop cut some HSS members several inches short. When discovered, instead of scrapping them, they cut them a few inches shorter and then used CJP welds with backing to extend them to the correct length. In this case it was cheaper than starting over and would have been a lot faster and better on the materials than trying to build them up with weld.
So it may depend upon how short the part actually is.
He Is In Control, Have a Great Day, Brent
I would have to believe such an approach, while valid, would have to be reviewed and approved by the Engineer since the weld in question is not part of the original design.
Best regards - Al
I would agree, and in this case it was. Just as with buttering up a large opening prior to welding, the procedure must be approved.
We were reviewing those same paragraphs on Tuesday, after finding a WF beam is about 1" too short. On Monday an RFI will be headed to the EOR.
We used to have some saw operator errors and ended up with columns and beams that were an inch short...before trying to manage a root opening that large, we would cut enough material off and then make a 1'-0 splice. Many times the EOR would rather go that route than trying to fill up a large bevel and the EOR would tell us which end that they would rather see the splice on.
just a thought to pass along....
I hear you on a huge gap. The minimum splice length allowed is 16", and the beams are normalized. I don't think there are any drops. I'm curious how the EOR will respond.
>The minimum splice length allowed is 16",
Is that a project specification? Did they use the nominal section size depth for the minimum length of a splice?
Just curious, I hadn't seen that on any of our projects to date.
Hopefully the EOR will have a solution that doesn't put the fabricator out too much.
Yes, project spec, not sure how that length was determined.
With regard to your finding of a WF beam that's about 1" too short... without seeing the actual detail of the beam, there may be another option that could be approved by the EOR that doesn't involve welding. If the beam is, say, a supported beam, i.e., a "filler" beam that has bolted framing L's at each end, new L's could be made with the L gage being increased by 1/2" more at each end, which would make up the 1". I've had this issue before, and submitted an RFI that (1) increased the bolted L gage by 1/2", (2) increased the bolted L leg to meet minimum horizontal edge distance requirements, (3) increased the L thickness (typically framing L's have 1/2" overhang at each end, whether bolted or welded, and in this case they would end up with 1" overhang at each end. I felt I had a better chance at approval if I increased the thickness of the framing L's. This hasn't happened a lot, but when it has, the EOR has always approved it. I've also taken the same approach with shop welded framing L's....(1) increased the welded L leg to achieve the same fillet weld length across the ends, (2) increased the L thickness, (3) increased the fillet weld size in accordance with the increased L thickness, and submitted a detail to the EOR.
But when you have a splice on the beam, isn't common to install a reinforcing plate on splice at the web after welding?
That will be a lot of work too. After the welding completed on splice joint, there is UT or RT to be done before you can install a reinforcement plate at the wed for fillet welding.
I have seen several instances where the beam web was reinforced with web plates (doublers) on each side. In those cases the "design" was an in-house activity without the services of a "real" engineer.
Some people fail to understand that the flanges are usually intended to accommodate the bending forces while the web counters the shear loads. The use of doublers in the web does very little to reinforce a beam that is designed to sustain bending loads. The shear load in the case of a simply supported member is negligible if the splice occurs at mid span. However, the bending forces in the flanges are at the maximum when the splice is at mid span.
If the weld is a CJP, the allowable unit stress on the weld is equal to the allowable unit stress on the member. The reinforcement is not really needed if the welds are deposited using a matching filler metal. That is, unless you have little faith in the quality of the welds, in which case, any reinforcement is better than no reinforcement, but it might be better placed on the flanges.
The embedded sketch shows the maximum unit stresses for shear, accommodated by the beam web, and the maximum unit stress for bending moment, accommodated by the top and bottom flanges.
Assuming the load is concentrated at mid-span, the beam is a simply supported member, and the connections are pin connections at either end (bolted web connections are considered to be pin connected), it would make sense to reinforce the web if the splice is close to the end of the beam where shear is at the maximum value. However, if the splice is toward the center of the beam, reinforcing the flanges would make more sense since they are load to their maximum unit stress in bending. The location of the reinforcement should be determined by the load conditions to maximize the value of the time, material, and labor involved.
Best regards - Al
I had a meeting today with the owner and I did use your explanation of not putting the doublers on web's splice joint. They were very upset and asked me to bring home & install the beam into my living room
..I think they were not happy when I told them "Real Engineer" will accept no doublers installed.
Now the owner wanted no splice joint, they want my boss to replace the whole beam with correct lenght.
Al you have to help me finding a new employer, do you have a vacancy for QC inspector? I can do ultrasonic thickness gauging on towers or ship tankers too
Sorry to hear your employer was not receptive to your comments.
Perhaps a little different tact would have been better. You obviously stomped on someone's toes when you said a "real engineer" would not use doubler plates in the web.
My comment was in regards to a splice mid-span where the shear load is "zero". In that case, the reinforcing plates added to the top and bottom flanges makes more sense. However, if the splice is toward the end of the beam, as is the case of adding a 16-inch length to the beam end, the shear stress is very high and reinforcing the web does make sense. Reinforcing the flanges would not be very helpful in that case.
Changing the supports also changes the nature of the loading. If the beam is part of a rigid moment connection, the moments at the end connection can be very high, thus reinforcing the flanges could serve a useful purpose.
A beam that is continuous across multiple supports also changes the nature of the loading. Continuous beams extending over multiple supports can result in load reversals.
The point I am trying to make is that all the details must be taken into consideration before a decision can be made as to the need for reinforcement and the placement of reinforcement.
I hope your employer understands you were trying to be helpful. It is easy to step on toes and bruise egos if a little diplomacy is not exercised when pointing out weaknesses in a design. I usually approach such situation by asking "silly" questions that gives the individual a chance to rethink their position and offers a graceful way to save face. I try to avoid the use of blunt force trauma except in the worst cases where reasonable responses are not forthcoming.
I don't believe you like it here in New England. I would be delighted if the temperature reached a high of 0 degrees C today, but it isn't going to happen for the next several days. It was about -14 degrees C last night. I do stay close to my wood stove on days like this.
Best regards - Al
Your input is very useful indeed. It’s good to be knowledgeable in the field but you have to understand the boundaries of your job.
Just try to imagine whether there are material stockists that sell beams of standard size with splice joint in the middle. I will advise my boss sell his beam
Al, I can’t stand cold weather, 17deg C is already too cold for me. Here in smokey the weather is 24 to 32 deg C. We stay in the beach with our ice cold beers to cool down
Don't rub it in buddy....
I have some business to attend to in Miami toward the end of the month. I can hardly wait! With my luck, it will be the first time in 100 years that it snows in Miami!
Best regards - Al
Back to the original question: the root opening was larger than permitted for a prequalified joint detail.
Several of the comments dealt with beams that were cut too short, but it did not sound as though any welding was required. That being the case, the approach noted by Scott sounded reasonable.
The responses that addressed an excessive root opening of a CJP groove weld has limited options. The one permitted by D1.1 allows the root opening to be reduced by building up the offending groove face with weld to reduce the root opening to an acceptable dimension. The other involved splicing a section that definitely requires the approval of the Engineer before implementation.
Without knowing the specifics of the situation, I hesitate to offer a fix because there are so many considerations to factor in. Is the connection designed as a ridged connection? Is the connection essentially loaded in shear? Does the connection involve beam flanges welded to a column flange, thus a rigid connection? How thick are the column flanges? Are stiffeners inserted between the column flanges and are they in-line with the beam flanges? How thick and how rigid are the column flanges and how thick are the beam flanges? The issue I am concerned with is Lamellar tearing within the column flange. Should the Lamellar tear occur, it is not typically visible since it is probably subsurface. UT is the one NDT method that can detect the problem if the technician is aware the problem is a concern. The Engineer must be aware of the potential problem so he can require UT and makes the UT technician aware of the problem.
A method that I have used to mitigate the potential of lamellar tearing in the field is to reduce the root opening to something that is acceptable (1/4 inch) before welding to the column flange. The backing bar thickness is increased to minimize any distortion that will occur because of the large amount of weld deposit required. The backing is welded to the beam, but not to the column flange. This allows the backing to "float" or move slightly as each weld bead cools and contracts. The beam flange is welded as shown in the sketch until the root opening is acceptable. The weld is allowed to cool (and contract) to the minimum preheat temperature before the final weld to the column is initiated. There may be a slight gap between the column flange and the edge of the backing bar. Not to worry, this is expected because the beam has cooled and contracted. This approach minimizes the residual stresses that can lead to lamellar tearing in the column flange. If the column has web stiffeners, the potential for lamellar tearing increases.
Best regards - Al
I raised this question because someone asked me about the tolerance that allows you to use the buttering welding to rectify big root opening.
My counterpart is arguing that clause 220.127.116.11 is not specifically meant for butering welding
I'm trying hard to think what else is new method
If as many passes as you show were placed, it seems to me that significant distortion would occur, and effective thickness of the CJP would result.
Al's suggestion to eliminate the lamellar tearing would also limit distortion. The free floating backing would eliminate the stress. Assuming a normal bevel shape could be prepared by the "buttering" passes stacked in a logical sequence.
No argument there. The backing does tend to curl upward, hence the increase in backing thickness to offer more resistance to curling. The other counter measure is to taper the thickness of the (top side) backing so that it is slightly thinner toward the column flange. That ensures the weld against the column face is no less than the thickness of the weld at the beam flange. The truth of the matter is that it doesn't make a lot of difference if the backing does distort slightly. The backing represents a stress riser where the backing is not fused to the column flange. The connection as shown is only permitted for static loading. If the joint is subject to cyclic tensile loading, the backing must be removed and the root rewelded. Hence the small amount of distortion that takes place isn't a major factor in the transfer of the load from the beam flange to the column flange. If the joint is loaded in compression, no problem. The misalignment resulting from the curling of the backing can be controlled if some forethought is given. It can be controlled to be within reasonable limits that will not affect the function of the connection. Are there limits to the size of the root opening that can be corrected in this manner? Certainly. I've used this approach to correct root openings that approached 1 1/2 inches. All the connections were subjected to UT once they were completed. The welding sequence is important. If the weld is completed in the normal manner, i.e., successive layers are deposited joining the beam to the column, there is an increased probability of developing lamellar tears in the column flange that is loaded in the through thickness direction.
The detail shown, as stated, is a field fix where it is impractical to splice a short section to the end of the beam that is too short.
Let's consider the situation where a short section is spliced to the end of the short member. Consider the amount of welding required to add a short section to the end of the beam. Both flanges must be CJP as well as the web if the welded joint is required to develop the full strength of the original member. How is the integrity of the welds going to be verified? UT or RT are the only two methods recognized as volumetric examinations and both incur considerable expense if the fabricator has to bring in a third party. At what point is it more cost effective to replace the member?
Scott's fix is reasonable as long as the dimension being corrected isn't too excessive. As the dimension that must be correcdted becomes larger and larger, the eccentricity introduced must be considered and the thickness of the connection angles become greater and greater. The fix is only practical for simple framed connections where moment is not a concern. At some point the correction becomes impractical.
Each situation is unique. There are several factors to be considered: the magnitude of the loads being transferred, whether the connection is subject to static or cyclic loads, the cost of labor, whether the fix is to be performed in the shop or in the field, whether the connection transfers moment, etc. I doubt there is a single fix, short of replacing the entire member, that is applicable to all situations. Most repairs are a compromise and few, except for the replacement of the member, is without increased cost, labor, and potential delays. The contractor's dilemma is to minimize the cost (delays in schedule, labor, material, etc.) of the correction without degrading the function of the component. The corrective action, if it is not within the limits provided by the fabrication code, requires the blessing of the Engineer.
The life of a contractor is not without challenges, complications, or risk.
The function of QC and QA is to ensure the fabrication meets the requirements of the project specifications, design drawings, and applicable codes. The goal is to inspect to accept, not to find a reason to reject. The TPI (verification inspector) responsibility is defined by the Engineer. Generally, the TPI serves as the Engineer's eyes on the job. The TPI provides the Engineer with information regarding nonconforming work (this is a good example) so the Engineer can make a reasonable determination of whether the work is acceptable "as is" or whether corrective measures are required.
A competent contractor will alert the Engineer to problems as they arise and propose corrective measures that the Engineer can approve or disapprove. It is generally the contractor's responsibility to propose a "fix" for nonconforming conditions.
In no situation should the TPI (verification inspector) propose a fix to the contractor. Any corrective action that is beyond what is permitted by the code should be "blessed" by the Engineer. The TPI should play no part in the process of developing corrective actions unless it is through the Engineer.
I've seen a situation were the inspection agency, with a P.E on staff, got themselves into a world of hurt because the inspection agency became involved with approving corrective actions without the Engineer's approval or knowledge. The inspection agencie's P.E. held the belief that because he was a P.E. he could propose and authorize corrective work. Ouch!
Sorry for getting off subject.
Best regards - Al
Many years ago I was facing a beam to beam joint with a huge root opening. The engineer had me do what you described above. I think I used 1/2" x 3" or 1/2" x 4 bar for backing strip. Tacked it to one side only, and started filling it up from one side.
These were then backgouged and backwelded as were similar joints on this job.
All this from a simple question about excessive root openings! Who could have known?
Best regards - Al
IS root opening is necessary for CJP welding of loose plate with existing beam web is field
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