Corrosion on painted stainless steel 1

[jkate]

Hello:

Looking for a little advice. We are a provider of municipal and institutional swimming pool filters. We have installations all over the world at various water parks, high schools and YMCA's. Occasionally, we get contacted from customers that have had the filters in service for only a few years notifying us that there are areas of corrosion in various locations. The filters are fabricated from 304L stainless steel which is passivated then primed and painted. Since these are swimming pool filters, the filter interior is in contacted with chlorinated water. Also they are typically located in a filter room that is sometimes a humid environment and sometimes have a chlorine smell. I've attached a zip file with some photos. Any advice or suggestions would be appreciated.

 

[TugboatEng]

The surface of stainless steel must be clean and free of contaminants to prevent corrosion. This includes paint.

The Nickel Institute has a white paper on the use of stainless steel in natatoriums.

https://nickelinstitute.org/media/1805/stainlesssteelinswimmingpoolbuidlings_12010_.pdf

 

[EdStainless]

You beat me to it Tug.
First, Why paint?
This is the real question.
Second, nearly all of those photos are of poor surface preparation prior to painting.
Is this 'paint' a two or three layer system?
Is it engineered for use on SS?
Are you blasting white and passivating prior to application?
Is this done in a controlled environment (dust, temp, and humidity)?
[URL unfurl="true"]https://res.cloudinary.com/engineering-com/raw/upload/v1658944776/tips/paint_and_corrosion_vsgl4c.pptx[/url]


= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[BiPolarMoment]

natatoriums

...word of the day, sheesh!

 

[EdStainless]

Common word, especially if you work in corrosion of SS.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[Dhurjati Sen]

Painting was probably done by the vendor to jack up costs to the naive buyer.

For unpainted components, the composition analysis of the SS 304 needs to be done, specially the carbon content.



DHURJATI SEN
Kolkata, India