Does anyone passivate their ss equipment? I’ve got two SS Brewtech fermentors and the included care information literature says to passivate once a year with a solution of Star San. However, the online information says to use a citric acid solution. I’ve had these units for several years and have never done it. Just curious if it’s necessary the home brewing level.
Commercial brewers passivate quarterly. Homebrewers probably don’t need to very often. If you get a metallic taste in your beer then you need to passivate your stainless. If you get rust spots then you also need to passivate.
Citric acid is what I would recommend using. I’m not sure exactly the percentage off-hand (4%?) but soak, drain and then leave to dry overnight (which will create an oxide barrier, then rinse.
A BYO article TLC for Stainless - Brew Your Own offers this: “To keep your vessel passive, or to repassivate it, all you need to do is clean it! Scrub your kettle till it shines, rinse it thoroughly and let it air dry for a couple of weeks. The passive layer will form naturally, spontaneously, as long as there is oxygen.” [note: this link no longer works]
Palmers first edition of How to Brew http://howtobrew.com/book/appendices/appendix-b/passivating-stainless-steel offers “The key is to clean the stainless steel to bare metal. Once the metal is clean, the oxygen in the atmosphere will reform the protective chromium oxides instantly. The steel will nearly as passivated as if it was dipped in acid. Nitric acid passivation creates a more chromium-rich passive surface, but is not necessary for brewing use.”
These are old references - I’m not sure what to think. But my brew kettle has been used for many years. I clean it every brew day with Bar Keepers Friend.
I have a lot of SS equipment and I have never passivated nor seen a need to.
Just here to pile on and say clean stainless plus air will passivate sufficiently for homebrewers. Commercial breweries have to think differently one because dumping an errant batch is more of an issue and two they tend to brew far more frequently which gets in the way of the surface oxidizing with air exposure.
Yeah, letting it “air dry for a couple of weeks” does not really work for a commercial brewer.
Some information on the how and why of passivation.
Nobody has time to passivate for longer than overnight. When I passivate a tank I double the acid from the standard cleaning cycle, run for about twice as long, drain and let air out overnight. That’s pretty much standard practice.
I have to agree with Denny that it is probably rare that a homebrewer ever needs to passivate. But if you pick up metallic-tasting beer then it’s either your water source or you need to passivate your kettle or kegs because you are literally tasting metal (ferrous sulfate)
Metallic taste can also come from oxidation, right?
I’ve never passivated any of my stainless steel brewing equipment and haven’t had any problems.
If you ever taste metallic from something that needs passivated you will know the difference. Literally taste like metal where as oxidation gives a metallic hint. It’s like sucking on a piece of rusted steel.
I agree there is a difference, but it can come from both sources.
I guess the difference to me is “sorta reminds me of metallic” as opposed to “I’m literally licking the sides of an old chevy fender.” 
At the Portland HBC i remember Ken Grossman talking about their passivating new kegs, as the factory delivered kegs weren’t good enough for Sierra Nevada.
Of course. But why not list all effects and causes?
Sure, why not? No argument there. But if you say "metallic, " the first thing that comes to mind is ferrous sulfate, not oxidation.
For me, it’s the opposite.
Well maybe you’ve tasted more beers from stainless steel that needs passivated than you realize. lol
Maybe, but I chalk it up to the fact that homebrew equipment doesn’t need passivation (usually).
I’m just pullin’ yer leg anyway. I don’t think I ever passivated homebrew equipment before either. Breweries use harsher chemicals and a lot more stainless steel real estate so they will definitely need it more.