I have been asked to create a validation protocol for localized/spot passivation. Our products consist of surgical instruments for the orthopedic industry. We use mostly 17-4 SS but have also used 440C. Occasionally, parts must be reprocessed requiring some additional cleaning around the reworked areas. How should I approach this validation? J.M.
ASTM (American Society for Testing and Materials) has a standard, A 380 entitled Standard Practice for Cleaning, Descaling, and Passivation of Stainless Steel Parts, Equipment and Systems. It discusses passivation methods as well as free-iron detection procedures. Those free-iron detection procedures are broken into gross and precision inspection methods. You should review the standard to see which type of procedure best applies to your parts.