plating, anodizing, & finishing Q&As since 1989
"Coating to stop caustic corrosion of SS316L"
We have palm size SS316L cast [CF8M?] machined one side, electropolished the other, equipment corroding in the field. These components are not stressed [housing only] but subject to steam/caustic atmosphere up to 300F, unknown concentration. Can we apply a coating to significantly reduce the attack? I was thinking of electroless nickel, NEDOX NH2, etc. Tolerances are not an issue.Sal Chirico
Honeywell - Vancouver, BC, Canada
Several years ago, Chevron found that a one mil coating of electroless nickel at least delayed caustic stress corrosion cracking of steel bolts in steel condensate service. Prior to plating bolts were failing in as little as 30 days. After plating they lasted for at least one year. With stainless steel, electroless nickel may also provide some galvanic protection.
Ron Duncan [deceased]
- LaVergne, Tennessee
It is our sad duty to note Ron's passing on Dec. 15, 2006. A brief obituary opens Episode 13 of our Podcast.
I am interested in this problem. Which side is the corrosion occurring? Machined side only? Was it passivated after machining? You should have good resistance to NaOH/300F steam with CF8M if it did not have some iron on the surface to start with. How long did it take for the corrosion to show up?
Castings can be fickle!
Stellar Solutions, Inc.
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