Passivate equipment...

[Tagobolts]

Searching the word wide webs has me more confused then anything...

Got a SS kettle and a fermenter (both SS Brewtech) and both need passivation. Kettle came in, still waiting for the fermenter.

So, from what I read, and everyone disagreeing there really is no best way to do it...

Instructions say to use TSP to clean and then use StarSan to passivate. After reading some very adament posters saying StarSan does not passivate and recommended citric acid. Hopefully you can help me make a decision.

In addition, what about the parts that come with the the kettle/fermender (connections, thermomenter, racking arm, etc). Do they also need passivation?

Will citric acid remove the etchings in the kettle and fermenter?

 

[SoCal-Doug]

Citric or nitric acid is your best bet for passivation

 

[Bilsch]

If you can find a copy of ASTM A967 somewhere it's pretty much the final word on passivation. If not then this site explains it nicely.

https://www.alleghenysurface.com/passivation-white-paper/

Interesting note: The idea of using citric came from the brewing industry.

 

[b-boy]

I think Barkeepers Friend will work as well. It uses oxalic acid.

 

[Tagobolts]

Thank you. What about the rest of the attachments. Should they be soaked in this as well?

 

[Qhrumphf]

From what I understand, phosphoric acid (ie what's in star-san) is good at cleaning stainless, and clean stainless will naturally self-passivate.

The problem is that contamination preventing full natural passivation and potentially seeding corrosion may be microscopic. To use star-san and let it form its own oxide layer afterwards you may have to use a really high concentration and still may not know for sure the job is done.

As opposed to nitric or citric that will passivate more directly.

Most commercial "nitric acids" used in commercial brewing (for both acid cleaning and for passivation) are a blend of both nitric AND phosphoric acid.

I know citric acid will work. Not as familiar with it though.

 

[Tagobolts]

From what I understand, phosphoric acid (ie what's in star-san) is good at cleaning stainless, and clean stainless will naturally self-passivate.

The problem is that contamination preventing full natural passivation and potentially seeding corrosion may be microscopic. To use star-san and let it form its own oxide layer afterwards you may have to use a really high concentration and still may not know for sure the job is done.

As opposed to nitric or citric that will passivate more directly.

Most commercial "nitric acids" used in commercial brewing (for both acid cleaning and for passivation) are a blend of both nitric AND phosphoric acid.

I know citric acid will work. Not as familiar with it though.

Thank you sir!
AND COYS!

 

[Rev2010]

Honestly, just skip it. If rust were to ever start forming you can simply repassivate then. I've done the starsan technique that many say does nothing. I haven't really seen any difference. I never passivated my previous Blichmann kettle nor my new Spike kettle. But after a couple of years when the bottom of my Blichmann started tarnishing and developing a buildup that couldn't be scrubbed out I used a strong starsan mix and that cleaned it right up. So I'd say don't worry about it for now as it can be done later if needed. Just give it a good cleaning.


Rev.

 

[SoCal-Doug]

Barkeepers friend works way better than starsan or PBW. It's specifically made for stainless steel. We use the stuff to clean welds on stainless and it even removes most of the discoloration from the weld.

 

[Iseneye]

I used citric acid powder. It is super cheap and easy.

 

[Rev2010]

Keep in mind if you do use Bar Keepers Friend, which does indeed work perfectly to passivate, to not use it over the volume etchings or it will fade them.


Rev.

 

[Qhrumphf]

From what I understand, Barkeepers Friend, like Star-San, won't passivate directly, but the abrasive plus oxalic acid does a good job cleaning the metal and allows for good self-passivation. Just use a non-metal scrubby, definitely not steel wool.

As long as you're taking care of your equipment properly, either method will probably suffice. You're not relying on CIP to clean a $20k commmercial fermenter or $500k commercial brewhouse.

 

[Vale71]

The issue with stainless steel is that while it will indeed passivate naturally if exposed to atmospheric oxygen, it will do so much more slowly than say aluminum. If the surface is not properly passivated and you start using it you might get pitting before passivation can occurr. There are instruments used to measure the degree of passivation in a non-destructive fashion but they're extremely expensive, as a homebrewer if you don't want to take any risk you just passivate for good measure or you just go ahead ans skip it and risk pitting (unless you have access to an acquaintance who works with stainless steel and has the necessary gear to carry out a measurement). Citric acid is the least expensive method and it won't remove etchings (tried it on my SSB Brew Kettles).

 

[Rev2010]

if you don't want to take any risk you just passivate for good measure or you just go ahead ans skip it and risk pitting

Do you have any reference links to this pitting information? As far as I recall reading pitting is generally only mentioned when it's said to avoid using bleach as it will cause pitting. I also recall reading that the vast majority of stainless is already passivated with nitric acid as part of the finishing process. I don't know of a single person that has passivated their home cookware, be it pots, pans, or cooking tools and I've never personally had pitting on those items nor heard any reports of pitting from others.

Not doubting you per se, just would like to see some good reputable information on this.


Rev.

 

[Vale71]

Just google ASTM A967 and you'll find tons of resources and info (the document itself is not free unfortunately).

Anyway, pitting is what you get with stainless steel when a surface is either not properly passivated or is attacked by chemicals for which that type of steel has a low resistance (also depending on actual concentration). Since there is no clear macroscopic fault such as a scratch or a crack where corrosion can start it will start at a microsopic level all over the exposed surface and these sites will then act as a sort of nucleation site (much like with CO2 bubbles) and increase in size until they become visible.

To get a uniform corrosion on the other hand you would need the passivation layer to be removed completely, and this can only happen with very strong chemicals.

Here is a quick reference of the different type of corrosions stainless steel can experience: https://www.bssa.org.uk/faq.php?id=9

I know that most stainless steel products are passivated at the factory for this very reason, but unfortunately our products generally aren't, hence the advice from the manufacturer to do that ourselves. It's also generally advisable to passivate any stainless steel implement that has been scratched, polished, or had welding work done as these are all processes that can cause passivation to fail locally.

BTW I've had pitting on the bottom of several stainless steel pots from poorly dissolved NaCl causing too high localized concentrations of CL-, but I'm guessing I cook pasta a lot more often then you do and am therefore more susceptible to this particular issue.

 

[Rev2010]

I know that most stainless steel products are passivated at the factory for this very reason, but unfortunately our products generally aren't, hence the advice from the manufacturer to do that ourselves

1. Some manufactures don't recommend it, such as Spike. Here they also include a pdf write-up about a study done regarding nitric acid vs citric vs air passivation that shows air nearly equal after 3 days time: https://spikebrewing.freshdesk.com/...-do-i-need-to-passivate-my-kettle-before-use-

2. How do we know for sure our fermenters/kettles aren't passivated? Been doing some reading and so far I'm gathering that highly polished stainless products are likely to have already been passivated in an effort to reduce the chance of dulling.


Rev.

 

[Vale71]

Anybody (including Spike Brewing) is entitled to their opinion and nobody must do something they don't whish to do. Your equipment, your money. I chose to passivate my SSB gear as it's still China crap, it's coated in machining oil which prevents natural passivation, and doesn't look highly polished at all but still cost some serious dollars (Euros in my case) so I chose to be rather safe than sorry. It also has welded ports and although the welds are polished (more or less professionally) I don't trust the Chinese manufacturer to have performed a passivation step on the welds and that is a definite must as you have a deadly combination of heat stress and mechanical polishing. If you browse around the forum you'll see several current threads started by people who got what to me looks like rusting from mechanical polishing residue (i.e. the sparks the grinder throws) that wasn't properly removed on their SSB kettles. But again, anybody will have to decide for themselves what risk they are willing to take with their own money.

But when I passivated I did indeed perform this step with with citric acid in a manner that is ASTM A967 compliant instead of just taking a shot at it with StarSan (which would have been much more expensive for me BTW).

 

[DiscDuffer]

Does any manufacture require this, other than SS Brewtech?

 

[Hayden123982]

Starsan works but you have to up your concentration on it. 4x concentration should work for the acid wash portion. And allow to air dry after you dump

 

[Vale71]

Does any manufacture require this, other than SS Brewtech?

No, no manufacturer requires this, not even SS Brewtech. It's just a recommendation.

 

[DiscDuffer]

Okay, does any other manufacturer recommend to passivate?

 

[Bilsch]

Starsan works but you have to up your concentration on it.

Actually no it does not.

 

[SoCal-Doug]

Unless you see signs that it needs passivating, there is no reason to passivate it. This is also called "pickling".

Simply put, the acid (citric, nitric, oxalic, hydrofluoric, etc) bath removes any iron from the surface and forms a coating (chromium oxide) that protects any further iron from reacting with the air. It doesn't do anything for making it pretty, cleaner, or shiny. So... unless you have bumped or scratched the stainless with something metal (that is not stainless), or you see signs of rust, there's no need to passivate it.

If you use an SOS pad, steel brush, or other ferrous metal on stainless, you will very quickly see why you shouldn't have. The contact area will rust.

 

[Bilsch]

Unless you see signs that it needs passivating, there is no reason to passivate it. This is also called "pickling".

Simply put, the acid (citric, nitric, oxalic, hydrofluoric, etc) bath removes any iron from the surface and forms a coating (chromium oxide) that protects any further iron from reacting with the air. It doesn't do anything for making it pretty, cleaner, or shiny.

Pickling is definitely not the same as passivation. Hydrofloric and HF/nitric pickling baths will remove a layer of the stainless taking scale and oxidadative discoloration from stainless surface. Passivating acids only remove the iron and leave the resulting chromium rich surface intact. Nitric acid will oxidize that chromium at the same it removes the Fe while citric on the other hand just removes the iron. It will however do that job better and to a deeper depth then HNO3. The chromic oxide layer then forms later in contact with air.

That's a pretty bold statement to say there is no reason to passivate. Are you absolutely sure about that ?

There seems to be quite a bit of misunderstanding around this topic even though good information on the subject is easy to find from reputable metal finishing sources online.

 

[Youngster]

Okay, does any other manufacturer recommend to passivate?

Stout does, I cleaned mine really well with a non scented soap (ivory) then used bar keepers friend for the inside.

I don’t think I used bad keepers friend on the fermenters, however I might run some through my CIPs for them.

 

[kevin58]

My first experience with the need for passivation was when I began all grain brewing. I had a new kettle but needed a pick up tube inside so I made one with copper plumbing tubing. It worked great but my entire batch tasted like pennies. That's when I learned about passivation and now treat every new piece of metal that goes in my kettles.

 

[NewJersey]

where can you buy citric acid and what kind of concentration cleaning solution s to be made?

 

[Hayden123982]

Actually no it does not.

Actually, yeah it does

There seems to be quite a bit of misunderstanding around this topic even though good information on the subject is easy to find from reputable metal finishing sources online.

Yeah there clearly is. The blend of phosphoric acid and dodecylbenzenesulfonic acid in StarSan will passivate stainless steel

 

[Hayden123982]

where can you buy citric acid and what kind of concentration cleaning solution s to be made?

Some homebrew shops carry it, otherwise amazon carries everything. Conc: 4 to 10% by weight in some warm water

Citric acid will remove the iron from the surface but it isn't an oxidizer so it can't help build up the chromium layer on the surface so I've heard to make sure you let it air dry so this can naturally occur.

 

[NewJersey]

Some homebrew shops carry it, otherwise amazon carries everything. Conc: 4 to 10% by weight in some warm water

Citric acid will remove the iron from the surface but it isn't an oxidizer so it can't help build up the chromium layer on the surface so I've heard to make sure you let it air dry so this can naturally occur.

the link up a bit said otherwise.