I'm going to try bar keepers friend next
Stick with
unscented Oxiclean for general brewery equipment cleaning. Or simply washing soda, which is Oxiclean without the oxygen.
And yes, Starsan for sanitizing. A working solution can be stored for weeks, months even.
Adding some (30%) of TSP or TSP/90 to (70%) Oxiclean makes homemade PBW, a more heavy duty cleaner than Oxiclean by itself. Use that where it counts.
Your kettle...
First off, I'm not sure the kettle actually needs (re-)passivation, but it may need a good, thorough cleaning.
Bar Keepers Friend (BKF) is NOT a general purpose cleaner, it's a fine scouring powder, similar to Comet, but without chlorine. Chlorine is very bad for stainless, especially when stronger and with prolonged exposure. It "eats" it, leaving pits. BKF contains oxalic acid. It removes scale, oils, and grime from (stainless) surfaces after fabrication, machining, etc. leaving it clean and shiny.
From what I understand BKF does
not remove the passivation oxides on stainless surfaces that are already there. But using it on unpassivated surfaces may leave new iron particles exposed after removing grime, etc. That's the main reason to re-passivate the surface (it removes the iron particles), while leaving Chrome and Nickel oxides behind that make it
stainless, and impervious to many chemicals and the brewing environment.
Sadly the oxalic acid in BKF is not strong enough to (re)passivate stainless, you'd need to use Citric Acid for that. Look up how that's done.
In short, in larger vessels, instead of filling them with 10-15 gallons of citric acid solution (it's very wasteful), it may be better to make a strong, thick solution of Citric Acid and continuously wipe it on the (now clean) stainless surfaces. It needs to be in contact for a few hours.
Maybe someone can chime in on that.
Use long rubber gloves and a face shield, or at least goggles, when handling/touching the acid.
Maybe contact Anvil about the need for this?