Effect of Temperature and Cooling Water Chloride Concentration on System Passivation of Brass Alloys in Petrochemical Facilities

Real-world plant experience along with a series of laboratory experimental studies is being used to optimize NOVA Chemicals corporate cooling water program.  All aspects of the program are being considered, including passivation treatments for individual bundles, system pre-film solutions, and long-term cooling water chemistries.  The aim of the optimization plan is to select the most favorable 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 deliver.

This paper will present results of electrochemical laboratory studies designed to provide an understanding of how each part of the program functions.  The focus in this paper will be on the passivation and protection of brass (Admiralty and Naval) heat exchangers with various yellow metal, azole-based inhibitors.  Their compatibility with a phosphate-based cooling water program at varying process temperatures and cooling water chloride concentrations will be discussed.