What type of clamp finish (i.e. unfinished or galvanized) do you suggest to use if dry graphite lubricant is applied to the clamping surface?

We recommend a galvanized finish.

24 Inch Bolted Clamp Pipe Shoe With Slide Plates For A Radiant Syngas Cooler Piping System
Bolted Clamp Pipe Shoes with Hot-Dipped Galvanized Finish