How frequently can lead-free brass be cleaned with CIP chemicals (e.g. PBW) before it begins to corrode?

Question

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?

Answer 1

According to data submitted with the patent, PBW corrodes brass at a rate of 11 ppm over a 20 minute cycle (see example four, towards the bottom). I'm not exactly sure how this is measured, but let's say that, hypothetically, you lose about 1 ppm of your brass every two minutes of contact time. Assuming this, to fully corrode your brass fitting to oblivion would take ~two million minutes in PBW. Let's say for argument's sake that your fitting is really compromised at ~1% corrosion. Even that would take ~20,000 minutes of contact time. There are obviously a lot of other factors here that aren't being taken into account, but it gives you a general idea of how little corrosion you're likely to see.

It might be worth finding an old junk piece of brass and submerging it in a strong PBW solution and leaving it for a few weeks, just to see what happens. Theoretically it should last quite a while, but I'd rather decide that from empirical evidence than from conjecture.