Chloride corrosion of stainless steel

[adt10]

Can stainless steel (304 and 316) corrosion occur by CaCl2 hydrates, mono and di, i.e., can the corrosion occur even if the salt is not in a solution? Appreciate hearing about your experience. Thanks.

 

[MJCronin]

Over the years, these fora have been loaded up with discussions about chloride corrosion of stainless steels.

Have you performed a search on the postings contained in eng-tips ?

MJCronin
Sr. Process Engineer

 

[EdStainless]

If they are really dry you will have no issues, but I have seen even ambient humidity cause serious issues.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[adt10]

Thank you for your responses. I just did a search, did not find anything applicable.

EdStainless,

In this application the air comes from a compressor. More than 94% of ambient moisture is removed in the inter-stage coolers. The remaining moisture is enough for CaCl2 to form mono and di hydrates, but not enough to make brine. In your experience with ambient humidity did CaCl2 adsorb enough moisture to make brine or did it stay solid? My suspicion is that even mono hydrate may have enough ionization so that Cl2 ions could attack the stainless steel. Your thoughts would be appreciated. Also would appreciate any literature reference you might have. Thanks.

 

[EdStainless]

My hunch is that you are correct. Unless your air has a dew point below -40 I think that you will likely have issues.
Once you get a little hydration the material will be more likely to stick, and then it is all downhill.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[Compositepro]

A brine will form on the pellets during the dehydration process.

 

[adt10]

Thank you very much. Appreciate all your comments.

 

[SJones]

J Zhang, et al, Micro-Droplets Formation During The Deliquescence Of Salt Particles In Atmosphere, Corrosion, Vol 61, (12), 2005, pp 1167 - 1172.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.