I'm using lead-free brass barb fittings until my budget gives me the thumbs-up on stainless. The only relevant information I could find is this BYO metallurgy article, which says:
The reason that brass fittings are not commonly used in commercial breweries is that the clean-in-place (CIP) systems and chemicals that are commonly used with stainless steel are too corrosive to copper and brass. As homebrewers, we don’t have to use such strong chemicals, nor are our parts in service 24/7, so corrosion is greatly reduced.
As a once-a-week brewer, about how frequently can I use CIP chemicals such as PBW in this system before corrosion becomes a concern?