Corroded Stainless Kettle - Solutions?

[day_trippr]

Hydrochloric Acid (aka Muriatic Acid) would certainly "resolve" this whole problem - by totally destroying the kettle
Avoid using any chlorine compounds on stainless steel, but especially not chlorine acids.

[edit] As for Phosphoric Acid, from British Steel "Phosphoric acid is not considered to be a 'passivating' acid but the clean surface left after treatment should allow the stainless steel to naturally self passivate."

I would stick with citric acid...

Cheers!

 

[pvtpublic]

Hydrochloric Acid (aka Muriatic Acid) would certainly "resolve" this whole problem - by totally destroying the kettle

That's what is recommended by Five Star. I've used it on all sorts of things myself, with no issues. It's a great way to shine up rims. I wouldn't passivate with it though.

I can't see it damaging the kettle unless you leave it for hours.

 

[impact.walter]

[edit] As for Phosphoric Acid, from British Steel "Phosphoric acid is not considered to be a 'passivating' acid but the clean surface left after treatment should allow the stainless steel to naturally self passivate."

I would stick with citric acid...

Cheers!

“Self-passivation” on SS can only occur on very smooth surfaces, and is predicated on a fine surface finish. Pits and fine marring in SS cannot self-passivate no matter the treatment, even under ambient gaseous conditions, if in the presence of an electrolyte (in this case moisture, salts, acid residue in the imperfections).

 

[day_trippr]

If one reads the following and still uses hydrochloric acid on stainless they own the results.
Emphasis taken directly from the following page:

Selection of stainless steels for handling hydrochloric acid (HCl) – British Stainless Steel Association

The common stainless steel types, 304 and 316 should be considered non-resistant to hydrochloric acid at any concentration and temperature.
Higher grades of stainless steel can have limited resistance, up to around 3% maximum at ambient temperatures, but may suffer local attack, mainly as crevice and pitting corrosion, even at such low concentrations.
The steep curves for 316 and the higher alloyed grades on the iso-corrosion diagram illustrate their very limited resistance.

Any additional chlorides or chlorine in the acid can be expected to make attack more severe.
Nickel based alloys, rather than stainless steels, should be considered for handling hydrochloric acid.

Contact between stainless steels and building mortar cleaners​

The use of building mortar cleaners that contain hydrochloric acid can result in staining and pitting to nearby stainless steel items.
Architectural metalwork and kitchen equipment has been reported with such problems resulting from either splashes or from the fumes given off from the acid.

Commercially available cleaning acids are around 16% hydrochloric acid.
Using these either ‘neat’ or as a one to one, (50%), dilution, which may be recommended by manufacturers / suppliers of these cleaners, makes these solutions extremely aggressive to most stainless steel grades.

It is advisable not to use such cleaners anywhere near stainless steel items.

 

[pvtpublic]

Why would hydrochloric acid be recommended if that's the case?

 

[day_trippr]

Recommended by whom? And why does that matter when that recommendation is highly suspect to say the least?

Can you actually read what is written by British Steel on this topic and still believe it would be wise to apply hydrochloric acid to the grades of stainless steel typically used in brewing gear?

Cheers!

 

[pvtpublic]

As I said, it's in Five Star Chemicals product guide. I posted the part above. #29

 

[day_trippr]

You mean this?

That is not passivation, this is a "nuclear option" for rehabilitating seriously damaged stainless steel. Exposure to hydrochloric acid will strip the chromium oxide right off the metal exposing the underlying raw material - the opposite of passivation...

Cheers!

 

[pvtpublic]

You mean this?

View attachment 827240

That is not passivation, this is a "nuclear option" for rehabilitating seriously damaged stainless steel. Exposure to hydrochloric acid will strip the chromium oxide right off the metal exposing the underlying raw material - the opposite of passivation...

Cheers!

Right, I wasn't saying it was for passivation. Citric acid is a good one for that.

 

[day_trippr]

For the same reason it's good for passivation (ie: it has an affinity for iron) Citric acid is good for removing rust as well - and without trashing the oxide layer that makes stainless steel "stainless". I actually use citric acid periodically to clean up random stainless steel items like my Hop Stopper (and before that my hop spider), my SS IC, and my various stainless steel stemmed cleaning brushes.

And Citric acid is cheap! Besides brewery uses we add a half tablespoon to the dishwasher to counter our well water carbonates and periodically have Amazon drop a five pound bag on us for $30...

Cheers!

 

[BayerischBier]

Thanks for all the discussion! This is helpful. Following up with some hopefully informative pics.

Looks more like there is still some flux or residue instead of rusty spots.

How did you remove the flux residual flux?
BKF and heavy scrubbing helped my stainless in the past as I run i.e. bowls in the dishwasher etc.

so if that is still flux, maybe use countermeasures for that (pending on type of flux), and then BKF?

just a thought.

 

[hotbeer]

I use a SOS or Brillo pad for things that are tough to get off SS. And even for just normal cleaning.

I've never had any issue with all the fears that 3M created for their promotion of Scotch Brite pads and the fears that were built on those.