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Derouging and Passivation: Economics of the current process

October 26, 2021

Derouging and Passivation are not trivial operations. The chemicals, labor, downtime, rinsing, and breadth of piping and vessels— not to mention third-party labor and material— can cost upwards of hundreds of thousands of dollars per year, depending on the size of the operation.

Derouging and Passivation are not trivial operations. The chemicals, labor, downtime, rinsing, and breadth of piping and vessels— not to mention third-party labor and material— can cost upwards of hundreds of thousands of dollars per year, depending on the size of the operation. Often water systems are down from two to seven days to complete all the processes and verify that the water system’s piping and vessels are devoid of any corrosion.

Considerable planning is necessary when contemplating a derouging/passivation operation. Typical checklist issues are: 


Additionally, if acids are used, what bases can be used to offset the low pH of the acids must also be considered. Typically, NaOH and NH4OH are the bases of choice. Operations are needed to understand the amount of base needed to offset the acids administered for derouging. Citric acid is often used for passivation and must be offset by a base to neutralize the passivation chemical to a neutral pH or higher. Most wastewater treatment plants (WWTP) can only tolerate pHs from 6 to 10 and often do not allow acid influent below pH 7.0 to their plants.

The biopharmaceutical industry has consistently performed derouging/passivation without any data. Frequency for derouging/passivation is often based on subjective opinions of the QA/QC department with nothing but historical mythology and visual interpretation of the corrosion. As a result, subjective opinions are translated into SOPs which determine the derouging/passivation frequency based on non-scientific data performance of the water system. This can often translate to derouging/passivation at a higher rate than necessary, exacerbating the costs of the operation. 


Real data provides real savings.

A biopharmaceutical company may have an SOP which delineates a derouging/passivation operation every 12 months. This SOP also might be 20 years old and has never been changed or analyzed for current operations. This biopharmaceutical company may be expending $250,000 per year with no scientific data to justify this operation. Often when a rouge monitor is installed, the frequency of derouging/passivation operations diminishes and can be delayed three years or longer saving the company $500,000 or more in expenditures and downtime.  

Without a scientific method to determine derouging/passivation frequency you might be wasting hundreds of thousands of dollars, every year, due to antiquated SOPs, historical mythology, and visual assessments of corrosion which are unfounded. 


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