Flange fix

Date 12-13-2002 13:48

I have a column that was punched at another location and brought to us to finish fabricating. Someone did not use the die underneath the punch and the punch did not make it through the flange, it only pushed the flange in the location of the hole. It didn't actually make a hole it made a large dimple in six locations. Without scrapping the piece, I was looking for some advice as how to fix this flange. The flange is approx. 1/2"-5/8" thick.

My thought was to weld up the front side of the dimple flush and then grind the back side back down flush and use a mag drill to drill the holes.
Any thoughts? or comments?
Looking for some help,
John Wright

By CHGuilford (****)

Date 12-13-2002 14:10

Provided the column isn't intended for a bridge or a fracture critical member, what you described is exactly what we would do. Just make sure the inside of the flange is flat enough for proper contact area under the fastener, or else grind it. And I would do some MT or UT to check for cracking.

CHGuilford

By jwright650 (*****)

Date 12-13-2002 14:21

Thanks CHGuilford,
I haven't ran into this one before. The guys that run our punch line have mis-located holes before, but they never made a mess like this. The company that sublet this job to us, has gone out of business and wants us to finish fabricating the pieces left outstanding to complete thier obligation to thier customer. We have a mess to straighten out. We have trailer loads of steel in various stages of fabrication to finish. These columns were already punched by them and they must have worn out thier punch and dies, because the burrs on the backside are large and have to be ground down.
Thanks for the reassurance on my fix,
John Wright

By TimGary (****)

Date 12-13-2002 18:20

Hi John,
While trying to weld up and re-drill misplaced holes before, I could'nt help but notice that is a good way to break expensive rotabroach bits. It seemed like the bit could'nt handle cutting a hole through steel with different hardness properties (ie. weld metal - base metal).
Can you make the repair and then re-punch the hole?
Tim

By jwright650 (*****)

Date 12-13-2002 18:39

Tim,
Too late, one of my fitters have already welded it up and ground it back down and drilled new holes, and the column is on it's way to the jobsite.
It turned out good, the flange is nice and straight. I have a great group of guys here, they do an awsome job. It only took them about an hour and they had the column repaired and finished fab'ing the rest of one's that were spread out on his table before I could get back over and Inspect the repair. I'm not sure how your shop is laid out, but we have a fitter and a welder paired up together on each table. While the welder is gathering parts, the fitter is laying out the main member. Once the fitter has fitted the piece both of them weld it up. They make good time. I've been in shops that had several fitters that fit up the pieces and take it down to another area where welders weld it up, the poor welders didn't get a break, welding all day. At least the way we have it, the welders get some fresh air, instead of welding non-stop all day.

We have broken a few bits from time to time drilling through that 70ksi weld metal.
Thanks guys for your help,
John Wright

By welder_guy2001 (***)

Date 12-14-2002 01:22

sounds like the original company was so out of money that they couldn't afford new punches and dies, so they just gave up...hehehehe

By jwright650 (*****)

Date 12-16-2002 17:34

You are probably right. From the looks of the fabrication and welding, they probably was not going to have any repeat customers. I sure hope all this fits when it gets erected. We are almost through with our part of it. One more small sequence to get fab'd and loaded.
John Wright

By DGXL

Date 12-16-2002 21:11

John:
Why not punch/drill oversized holes as permitted by AISC and use weld washers?