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"Built Dam Strong!"

15 March 2014

Upside down and backwards. *sighs* (AKA: How to fill holes in thick steel, by a retard.)

I've been a colossal retard at work the past two days. I managed to weld on a bunch of stuff to a beam upside down. Brilliant, right? Sometimes this isn't really much of an issue, as the attachment holes, see here:

 Are pretty close to being symmetrical. Guess what? These weren't. )(#*$)(*#$

So, I had to start on the adventure of filling 24 holes and re-drilling them. The rest of this post is basically a how-to of filling large holes in fairly thick steel.  Good for you, bad for me.

First, you take your trusty copper bar that looks really crappy (but that is a good thing):
And clamp it underneath the hole you want to fill. The reason why you want a crappy, used bar is that if "seasoned" correctly, there will be a depression or three in the bar, which will let the weld come through the other side a bit, making a better tie in with the metal and when ground flat, shouldn't leave much in the way of tell tale signs that there has been a hole welded in the area.

So then you get to welding:
Yes, it gets HOT. You want it hot. The hotter the better, as the heat will float the flux out of the puddle. (If you are using fluxcore or dual shield. MIG is much cleaner at this and is actually much easier overall, but, we don't have MIG at work, so I do what I have to.)

If you get the weld done correctly, you shouldn't have to do too much else. It took a few holes to get comfortable with the process, as it is pretty involved. I didn't fill a few enough and the centers sunk when they cooled:
I did need to touch up some areas, but it wasn't too bad. This is what the first batch of holes looked like when I finished:

The biggest things to watch out for are the first pass around the base of the hole. You want to make sure you really burn that in and that you fill in the center as you go. I basically spiraled my way up a layer at a time then looped through the center to make sure that filled int he center and didn't leave any slag voids in the weld. I was very successful at this.

One of the signs that everything went well is that you have to use a hammer to tap the copper bar off the weld. DON'T smash the end of it down! You'll bend it. Tap it back and forth. This keeps it flatter and work hardens it less.

This is what a good, penetrating weld will look like:
 Yes, it is ugly, but most of that is from the copper slag/gunk/WTF.

 Here is some perspective on how much the underside sticks out when you get through:

So, then you spend a long time grinding carefully.

A very long time. Very carefully.

You can't just dig in willy-nilly. You have to keep the surface as flat as possible, as this is where the beam gets bolted onto the connection on a column. This is the weight bearing and torsional connection. It has to be as nearly exact to the original dimensions as possible. 

After everything is ground flat, you lay out your hole pattern, quadruple checking that you are doing it correctly this time, you grab your amazing awesome magnetic drill:

 and the correct sized annular cutter (it is NOT a drill bit!!!):

And get to drilling. I love this setup. The annular cutter has a bunch of teeth that cut a circle in the correct diameter while leaving the center of the material intact. This is much faster than taking a big honkin' drill bit and trying to remove all that material at once, since each tooth is removing about a 1/8" wide swath as opposed to two or MAYBE four flutes removing an entire radius' worth or material. The center point you see above drop into a center punch to locate the drill. There is a switch that you flip to activate the very strong electromagnet that keeps the drill positioned correctly on the surface, then you start the drill and feed it down with the levers. This process requires coolant which the operator squirts onto the bit at regular intervals. You can get a much superior hole in less time this way than with nearly any other more typical or traditional drilling methods. I love this stuff!

One side drilled:
 You'll know that you had a good weld when you find no slag voids along the edges of the holes. I found one hole to have them. 23/24 is VERY good for this sort of thing, better than most. I will say I have too much experience filling in holes like this. A lot of things in the Army get worn and had to be rebuilt or holes relocated, so this whole process isn't foreign to me at all.

Even so, it isn't even all that bad:

 I know the picture is crap, but it's what I can do with my phone. heh

 The final bit in the process is basically to hide the fact that I did all this work. It is not not permitted to do this, it is just a hassle if you get an inspector with a bug up his butt who wants to UT (Ultrasound Test) the whole fix JUST because it was done. Meh.

The thing that stands out about the repair is how shiny everything is when it is ground. Shiny on these beams sticks out worse than a pink tutu wearing ballerina at a dive bar one Friday night after a home team looses an important sporting even. To cover it up, we take used grease (from any one of the trailers, forklifts or yard switchers) and slather it on thusly:
 Once it is wiped off, it leaves a much less shiny finish and a few days out in the yard in the weather will let the steel regain its natural protective oxide coating (structural beams are nearly always made of "weathering" steel these days).

So after I get all that done (which took over a fill day's worth of work), I weld on this top plate:

As soon as I finish welding it on, I realize that I welded it sticking off the wrong side. *sighs*

That will get fixed on Monday. *shakes head* I just couldn't win this week.