Tea stained 316 balustrading 1

[nickt1960]

I have had some s/s balustrading installed at home which has already started "tea staining" after just a couple of months. We are at least 10 km away from the coast, and hence insisted on using 316 s/s instead of 304. I am convinced that the fabricator has used 304 for some sections of the balustrade and I was wondering whether anyone could tell me of an easy way to non destructively test the balustrade for Mo content to verify the correct material was used.

 

[EdStainless]

There is such a thing as the Mo spot test. You could find a kit by searching the internet. You really need known samples of 304 and 316 to check so that you get a feel for the test.

The staining maybe because the surfaces were not properly cleaned before installation. They should have been passivated with acid in order to remove any embedded iron in the surface.
What kind of surface finish does this material have?
If they ground or polished with any tools that had been used on carbon steel then there will be a bunch of iron in the surface that will cause this staining.

You could try contacting a local welding supply and buying a bit of pickling paste. If you clean an area with the paste and then rinse very well I doubt that you will see the stain return.
Have you contractor come out and acid clean the whole thing.