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Stainless steel black spots in salt water environment

August 24, 2010

My company is in the food loading business using stainless steel parts and assemblies. We currently have a situation where our customer uses our machine to load their products which have been processed in a brine solution. The solution appears to be causing or accelerating black spots near an area where we have stainless 304 sliding across teflon coated stainless 304. Is the water turning black because the stainless is being corroded by the salt or the slight friction of the 2 parts rubbing each other. We only see this when our customer introduce salt water or mineral oil onto the system.

Thanks for your help.

Eric Hubbard
Engineer - Waynesboro, Virginia

First of two simultaneous responses -- August 27, 2010

I have since found out the teflon coating is actually over a ceramic coating which contains nickel and chrome. Will the nickel turn black if attacked by the salt solution?

Eric Hubbard
- Fishersville, Virginia

Second of two simultaneous responses -- August 27, 2010

Stainless food equipment used with brine solutions are a highly at-risk surface, much like stainless at a swimming pool or on an oceanic coastline. The customer may need to start a program of periodic maintenance repassivation of those surfaces in order to keep the corrosion in check. Let us know if we can help you.

ray kremer
Ray Kremer
Stellar Solutions, Inc.
supporting advertiser
McHenry, Illinois
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