Metal finishing Q&As since 1989

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Industrial equipment passivation and effects on microorganisms?

2003

I work for a Solid Dosage Drug Manufacturer. Recently, one of the manufacturing lines incorporate a NEW PRODUCT Bowl to the Drying Area. These bowl is where the blended and lubricated solution is dried in order to be Compressed into a tablet. My situation is the following: the procedure for new equipment (product contact like this one) is to go through a chemical cleaning and acid passivation prior to be used. By doing this the area makes sure no that no microbial contamination is present before its used. A rinse sample is taken to make sure no acid is left in the equipment and a swab (surface sample)for microbiological purposes is also performed. In this specific case, the bowl went through all the cleaning and passivation process and the pH (rinse)but the swab for Micro was not performed...The equipment was cleaned with a chemical detergent (0.1%/wt NP-9) for 15 min., the with 3.5%%/wt citric acid [on eBay or Amazon] for 2 hrs. (pH4), this same solution is brought to pH 8 with Triethanolamine and rinsed for 5 min. and finally the passivation stage 0.25%/wt of Sodium Nitrite is added and used on the equipment for 30min... My question to you is: Do you have any information regarding the effects of this type of passivation in terms of microbiological contamination?

Miquel F. Batlle
pharmaceutical - Caguas, Puerto Rico, USA,

Miquel, you have not applied a typical "passivation" procedure to the stainless steel bowl. The cleaning procedure you are using is a typical routine cleaning and does not include the use of a sanitizing agent to kill microbes. As a result, it is possible that microbes could have survived the cleaning procedure and will contaminate the material you are processing. To prevent this, the equipment should be treated with an EPA registered sanitizer after the cleaning step and just prior to a final rinsing with water.

Roy Nuss
Trevose, Pennsylvania, USA
2003