First step is to remove the lip from the 9 flanges that will be used to support the shelves so the pipe slides all the way through. I used a metal hole saw to get the majority of the lip out and then used a grinder to get the remaining.
I forget the exact size of the bit (after the 9 flanges it was useless and thrown away) but it just fit inside the flange.
The flanges were screwed down to the table to keep them secure during drilling
note: the following action likely voids any guarantee or warranty the Kee Klamps have.