not worried about the chlorine on stainless?
It's free chlorine that's the concern, and even then only when it gets above ~25 ppm. In alkaline solution the chlorine remains bound - I want to say the threshold is ~11 pH, but I can't recall offhand. As long as the caustic is mixed appropriately and not allowed to dry on the surface, and there's no residual beer or CO
2 to acidify it, there's no risk of pitting.