Rusting Stainless Steel

I converted some keg's into a MLT, a BK and HLT and a Fermenter. I used a Rotozip to cut the tops off and a dremel sanding disk to smoothout the cuts. I just tranfered my first batch from the fermenter to the keg and I noticed that there is rust around most of the lip to the vessle where the rubber gasket and the lid meet. I also noticed the rust only occured where the sanding drum scratched the surface a bit.

I assume that the small pits that were created allowed for rust to form (still not sure how since it is stainless steel) but what are you guys doing to combat this? Do I just need to clean it very good each and every time and deal with it? Are there coatings that are being used?

Could have been some iron in the tools and shavings are reacting.

Most likely is that there was no re-passivation after the cut. Stainless Steel is not rust proof when the passivated layer had been comprimised.

Have you any StarSan and a weeks time? Maybe even try Oxalic Acid (Bar Keepers Friend) to clean the rust and jump start the natural re-passivation.

GilaMinumBeer said:

Could have been some iron in the tools and shavings are reacting.

Most likely is that there was no re-passivation after the cut. Stainless Steel is not rust proof when the passivated layer had been comprimised.

Have you any StarSan and a weeks time? Maybe even try Oxalic Acid (Bar Keepers Friend) to clean the rust and jump start the natural re-passivation.

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I have time but I am not sure I understand? Just put some BKF solution on the area and let it sit?

No. Use the BKF as a paste to clean the rust and then rinse. There will be enough residual Oxalic Acid left behind in the open pores of the steel to start the re-passivation process.

Let the whole thing set exposed to air (garage, etc..) and let it fix itself. Should take a week. Maybe a little more.

GilaMinumBeer said:

No. Use the BKF as a paste to clean the rust and then rinse. There will be enough residual Oxalic Acid left behind in the open pores of the steel to start the re-passivation process.

Let the whole thing set exposed to air (garage, etc..) and let it fix itself. Should take a week. Maybe a little more.

Click to expand...

Great thanks - I assume that a non-abrasive (3m pad) would be the best fit for the paste unless you have another idea? Definitly appreciate the feedback!

I always just used an old dish scrubby sponge.

Let the BKF do the work.

All this advice is correct. Just make sure not to use any steel while cleaning the area. Small pieces of mild steel can clog the pores of the stainless (analogy only) and rust and form nucleation points for more rust in the future. A green 3M pad would be perfect.

Both posters gave great advice. The re-passivation happens very quickly. In your particular case, I doubt the SS is rusting but iron that was embedding in the SS with the tool. When I built my stand, I was in a hurry and the grinder had a regular wire wheel in it, not a SS wheel. The areas of my stand that I hit with the wire wheel are all rusting from the metal I embedded in the SS.

I need to go back and hit them again with the SS wheel. What was it my dad told me when I was a kid? "Never enough time to do it right but always enough time to do it over"

If I use the gator-pads suggested in other threads to polish and make the keggle's all pretty and shiny do I need to do this (this being re-passivation) to the entire external surface?

Excellent question!