cutting off and rewelding flanges on Imbed

By eekpod

Date 01-18-2007 21:18

I can't picture what you are dealing with, can you post a couple of photo's, maybe that will help us to help you.

By osemmes Date 01-19-2007 01:32

Thanks, my scanner just died. Will provide sketch when able.

By XPERTFAB (**)

Date 01-19-2007 06:20

Are these flanges you speak of to attach structural pipe columns or fluid/gas conveying process piping? Or are these flanges what is commonly known as shear clips used to attach beams and/or girders to precast or cast in place concrete wall panel using some modular form such as Symonds? Are the members that attach to these flanges to welded or bolted to such? With some of this information, I would be better able to assist you as your problem sounds like one I frequently encounter.

By osemmes Date 01-19-2007 17:51 Edited 01-19-2007 18:17

Flanges (tabs) attach to steel plate embedded in concrete columns. Shear clips is better term. The girders are bolted to the shear clips. One reason for welding to plate is to accomodate small variations in alignment before welding. I will try to attach a sketch.

Cutting off the shear clips on-site with torch will likely result in a jagged cut. Our concerns are difficulty of getting a good weld because of of the jagged intefaces likely to occur.

Thanks for your willingness to help.
Imbed Problem.
The design calls for "imbed" to be delivered in two pieces, the portion to be set in the poured wall (A) and a flange (B) to be welded on after the concrete had set and forms removed.
Unfortunately, the two pieces were welded at the fabrication point and delivered as one unit. Thus, the form would have to be cut to allow the flange to protrude beyond the outside of the form. The forms are metal and constructed in such fashion that "through-form" placement would not be workable.
The decision has been made to separate parts A and B using a cutting torch, pour as planned, and re-weld B onto A after forms removed.
My concern is that the site-performed cut will be jagged and possible prevent a good fit between welded surfaces.
There may also be an issue with applying heat to the coating... depending upon the type of coating.
Please comment

Attachment: imbedsandtabs.tif (21k)

By eekpod

Date 01-19-2007 20:58

The sketch definitely helped.
I don't work in the field, I'm in the shop, but we do have some concrete panel's that have in-bed's set in them, ours are a different type.

Let me ask this, with the plate already set in the concrete, why can't they cut off the tab (B, I think it was labeled), grind the remnants off so now the imbed plate is flush and relatively flat, and instead of using the tab you cut off, can't you replace it with something else? , either a plate or angle, anything so that you won't have to deal w/ that ragged in- field torch cut. Or after they cut it off, again grind the imbed plate clean and flush, then "repair" the tab by welding it and re-establishing it to what it was supposed to look like from the start.
Basically what I'm trying to say is it appears your going to have to get to the point that they should have been delivered to you, but your going to have to get their the hard way, with some time and money.
I agree w/ you that the work in the field will definitely end up w/ a jagged cut, and that doesn't set itself up for a good fit-up later on.
Again, I don't work with this system myself, but I don't see any other way, maybe someone else can be of more help. Good Luck

By osemmes Date 01-19-2007 21:50

We need to cut off the tab before forming up, because we would have to cut through the metal forms otherwise. I believe the grinding is excellent approach as well as the new tabs.

On commercial construction in your state to what extent is an AWI required? Does an AWI need to approve shop drawings for the structural engineer?

Thanks for your response.

By darren

Date 01-20-2007 06:46

if full pen is required just bevel the part and grind back side of root pass, weld at low temp and you have to wait for a few days after pour before welding, the moisture in the concrete will cause the concrete to explode. when you do weld then only put one maybe two passes in at a time as too much heat input will definatley affect concrete. as for jagged cutting, get some one who knows what they are doing with a torch! the coating is going to be destroyed no matter how you do it. also if they were supposed to be shipped seperate then what is the possibility of sending them back, or having local shop/guy build you new ones and backcharge. you did not mention how many you require and what your time frame is.
darren
p.s. as most of the field guys out there will tell you this is a minor problem and shop product always has to be reworked in the field for final application. just remember that whomever's fault it is is also who gets the bill.
you gotta burn to earn

By osemmes Date 01-20-2007 18:20

Thank you for your comments. Make sense to me.
OJ

By billvanderhoof (****)

Date 01-20-2007 08:18

It might be cheaper to cut the form panels and then repair them later. Just guessing.
Bill

By osemmes Date 01-20-2007 18:21

Thanks. Will discuss with form panel leassor
OJ

By eekpod

Date 01-21-2007 19:45

I'm not familiar with AWI, are you referring to a CWI? Certified Welding Inspector? As far as approval of drawings , that's done by the engineer of record, that's not an inspector's position to approve drawings. All our drawings are stamped by the engineer, and he sign's off w/ a date and signature.
Our company, after receiving the approved and signed drawing's from the engineer makes the appropriate amount of copies, for instance the shop, drill line, detail, QC, foreman, office and master, then they are distributed to each party.
I agree with the other post that whomever it is determined made the mistake, they are the one's who will ultimately get backcharged for the time and material. When mistakes hold up other trades and they start charging you it can get real ugly and expensive in no time at all. This is why it's important the "cover your ass" and save all notes and documents so that hopefully you won't be the one stuck. But also if I missed the issue, I'm also the first one to admit it and try to get moving forward. Good Luck Chris

By osemmes Date 01-21-2007 21:22

Thanks, Chris.
Our engineer of record did provide the drawings and has nearly 27 years experience.
I was concerned about the comment in one response about the concrete "exploding" from overheating while welding metal embedded in concrete not fully cured. I suppose that would be a problem whether or not the assembly had been shipped in two parts or one (and cut off and re-weld the tab in the field).
I am not yet sure what welding certification/licensing requirements apply.

By hogan

Date 01-22-2007 22:57

spalling of the concrete is not that big of a problem if you allow the concrete to cure and keep the heat input down

By darren

Date 01-23-2007 03:58

i did state in the response to let the concrete cure and keep heat down , limit passes and all that. definately do not weld while the concrete is wet, even after it has cured. wire wheel the imbed before welding not only does it make for a better weld but the smoke from welding over concrete dust/ powder takes your breath away, actually hurts, some of the worst smoke i've ever come in contact with. these are hard lessons to learn first hand so its great your asking questions before proceeding. just stay focused and it will all go great
darren

By osemmes Date 01-24-2007 21:19

Thank you, Darren.
Good inputs. Breathing difficulty is not a good thing when welding 50 feet up on form.
OJ