I've got a 3 keggle eherms system on a wood platform/table, and I'm not sure if I need them, but I have 3 round pads under them. I forgot where I got them, but they are cork with a painted/lightly laminated surface on them. I had a boil over on my boil kettle, and the water just trashed the pad under that tank. Had to throw it out after one mishap.
I strongly suggest not using cork under any kettle that can leak water........
Damn. I've got to get a better signature.
Borderline Brewing Co. Nashua, NH