Bruce wrote:

snip--Eric's good primer on pickling and passivation of austentetic stainless steels
Pickling and passivation


Thanks for quote. I knew that stainless reacted with oxygen to form a
non-corrosive surface and that unless you had a flow of water the lack
of dissolved oxygen might result in crevice corrosion but somehow had
never related it to pasivating. I'll now use at least come nitric acid
as an oxidizing agent.

Bruce in Bangkok
(brucepaigeatgmaildotcom)

Bruce,

I'll try to steer you to looking into stainless
steel passivation using strong citric acid (ie
Citrisurf, etc.) once more. I've not time to
provide the relevant links at the moment.

Use nitric acid if you like. It works also,
although not as well as citric acid according to
various studies. It is also much more hazardous
to transport and dispose of. Citric acid can be
diluted and legally flushed down the drain.

Citric acid passivation for SS is fairly new
technology, and Nitric acid is the traditional way
of doing it. Citric acid can also be used with a
power supply to electropolish stainless steel.

The people who turned me on to the citric acid
passivation do a lot of industrial and food grade
stainless welding and have switched over.

Good luck,

Don W.