A combination of laboratory experimental studies and the results of real-world plant experience is
being used to optimize the corporate cooling water program. All aspects of the program are being
considered, including passivation treatments for individual bundles, system pre-film solutions, and longterm
cooling water chemistries. The aim of the optimization plan is to select the combination of
passivation, pre-film and cooling water solutions that provides the most cost-effective protection of the
system within defined performance targets that the vendor must meet.
Electrochemical techniques are being used to investigate the passivation, system pre-film, and
cooling water solutions and how they interact with each other. Developing an in-house experimental
capability helps in making informed decisions between different vendors products.
Here, the results of electrochemical tests to investigate the changes in corrosion behaviour of
carbon steel on transitioning from a nitrite-based passivation solution to a phosphate-based cooling
water program are described. The change in protectiveness of the film can be observed during the
transition, as can the possible susceptibility to localized corrosion.
Keywords: cyclic voltammetry, EIS, carbon steel, cooling water, nitrite, phosphate, OCP