Welding Tips and Tricks

So I had a project come in the shop yesterday, a 1950's era water cooled taffy table in need of a rebuild. Upside down in this pic, the thing weighs about 600#. The entire top and sides are 1/2" thick steel and has a sheet of 1/4" steel bolted to the bottom. There are four chambers to control water flow through the table with an inlet and outlet pipe in the ends.




50+ years of gunk...



My goal is to replace the bottom sheet (1/4") and brace the legs. The customer wants me to cut off the flange around the top and simply weld the perimeter of the sheet.



My question is what would be the best approach to welding this to avoid warping? I figured I would tack the snot out of it of course but I'd like to avoid a bunch of stops and starts. I'll also be welding some angle iron across the middle to keep the bottom from developing a sag like the previous one has.

Any suggestions on how best to tackle this one?

I know rebuilding it to original spec would be the best way to do this, but the customer wants it welded so it isn't my decision. Also, this is a bit time sensitive since he is opening a confectionary shop next week and this is an integral part of his business. I don't have time to get the top milled and the bottom piece drilled for 200 bolt holes...

I would build an angle iron framework on the 1/4" to fit just inside the 1/2" then cut the flange off make sure you put the water holes in the angle iron frame. Skip weld the angle but weld 100% then instal in the 1/2" section and again skip weld 100%. Hope that helps I was looking at the pictures and typing this on my phone so I may not grasp the project fully.

AKmud.

From the photos it seems that part of the built-in stiffness on the 1/2" thick top piece is due to the flange, giving it a sort of angle-iron frame. To remove the flange would also mean to lose part of this stiffness. So if the Client is insistent upon removing the flange, then you would need to regain that stiffness. The 1/4" bottom welded to the top would also act as a flange and make it very stiff. You may consider welding some rectangular tubular (with at least 4mm wall thickness) as stiffeners within the top piece, or angle-iron. The 1/4" bottom plate could also be slot welded to the stiffeners.

How will you clean out the corrosion from the top piece?
How much of the wall thickness of the top piece was loss due to corrosion?
Was the distortion (sagging) only in the old 1/4" piece?

Tanks.
Alexa