SEDL / STP / STP908-EB / STP17463S

Design Considerations for Occluded Cell Corrosion Monitoring

Silverman, DC
Associate fellow, Monsanto Chemical Co., St. Louis, MO

Krisher, AS
Technical director, Materials Technology Institute of the Chemical Process Industries, St. Louis, MO

Pages: 20    Published: Jan 1986

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Abstract

Occluded cell corrosion is a major contributor to unexpected and premature failures. A reliable, on-line instrument to monitor for occluded cell corrosion would generate benefits of a decreased frequency of failures and a more reliable estimation of service life. This paper reviews the thermodynamic and kinetic bases for such a practical monitor to show that the concept is sound. Crevice dimensions, cathode-to-anode area ratio, and defined hydrodynamics—parameters important in the in-plant monitor—are defined in this discussion. Finally, a conceptual model of a proposed in-plant monitor is presented. The dimensions and geometry are derived from the discussion of the theory.