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Passivation method without total immersion

We are also experiencing problem with corrosion problem on our 304 and 316L machined parts. The passivation process can be of help to our problem. Because of the absence of space and facilities, can we conduct passivation not by total immersion of the stainless parts on passivation bath but by just wiping the whole surface of the parts with the passivation solution?

Edgardo V. Eleria
Tool and Die Making - QUEZON, CITY, National Capital Region, Philippines
2004

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First of two simultaneous responses --

It is possible to passivate without total immersion. A commercially available gel product, non-nitric acid, is available that is used by applying with a brush, allowing to stand for 15-30 minutes then rinse or wipe off. Passivation results are very good with this method when parts are too large for immersion.

Regards,

Dayton Dailey
- Lake Zurich, Illinois, USA
2004

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Second of two simultaneous responses -- 2004

Yes. We routinely passivate large equipment by a spray application. Rather than wipe on the chemical, I suggest a low pressure spray. Thickened chemicals that can be pumped yet still have plenty of adhesion work well, even on inverted surfaces.

Due to the absence of heat as you would find in a heated bath, I perform two applications of chemical and include a pressure rinse of at least 1250psi. Water quality is also critical. I use filtered De-Ionized water.

We also remove rust in the method.

Todd Turner
- Monroe, Louisiana