Stainless steel and salt additions - corrosion?

[UKSkydiver]

As per my brewdays post;

Last night, I used calcium chloride for the first time.

I prepared my water and malts last night and then set an automatic timer to turn on early doors. What I failed to do was make sure the flakes were fully dissolved and I think either the presence of the flake itself and / or the presence of heat from the element has corroded the stainless steel

Any chemist / metallurgist care to confirm my suspicions and is there anything I can do to remedy the situation?

Thank you

 

[kelper]

Are those pits or just stains? Even an inert object, lying on a metal, can cause a drop in the dissolved oxygen underneath it, triggering a small corrosion cell with the uncovered metal. This is worse when the water is made conductive by salts like calcium chloride.

 

[UKSkydiver]

It is pitted - where it wasn't before. You can feel it when you run your finger over it (when the element is off )

 

[kelper]

Unfortunately, the only repair would involve welding and that's very tricky on thin s/s.

 

[UKSkydiver]

Ok thank you
So next q?
Will it get any worse or have an effect on the brews?
Cheers

 

[foxy]

You could try passivation of the area use some citric acid or even Star San.

 

[kelper]

It won't progress if you keep the s/s clean and dry when not in use and don't do any overnight soaks with undissolved chemicals. Definitely passivate as suggested.

 

[Kveik Freak]

If you are using tap water then lowering mineral contents would be a much better idea than adding more minerals.

Look up your local water company's website and get their figures for your water supply to get a rough idea of where you're at chemically. I'm guessing it's hard as nails.

If I were you I'd find out my approximate mineral contents and sulphate:chloride ratio then look for a mineral water or waters with much lower overall mineral contents that I could use to adjust the concentration and the sulphate:chloride ratio as required.

Otherwise you can use acids to precipitate some of the mineral content out, but this is a faff, and if you've no way of knowing exactly what is coming out of your tap that day then you run the risk of ending up with different mineral contents and ratios than you intended.

 

[UKSkydiver]

Thanks guys - will look to see what passivation involves (I did read about it once, but I didn't need more than that at the time)