SEDL / STP / STP741-EB / STP28263S

The Relationship of Coatings and Cathodic Protection for Underground Corrosion Control

Toncre, AC
Engineering consultant, Arabian American Oil Company, Dhahran,

Pages: 16    Published: Jan 1981

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Abstract

External corrosion control for buried pipelines and other metallic underground structures is accomplished industry-wide by using dielectric coatings supplemented by cathodic protection. Relationships between these two corrosion control methods are outlined to show how effective corrosion control can be achieved.

The long-term changes of protective coatings in relation to their porosity, permeability, and osmotic action under electrical potentials are discussed. Evaluation of existing criteria for adequate cathodic protection of underground metals with poor or disbonded coatings, in conditions conducive to stress corrosion cracking and other localized corrosion phenomena, indicates a need to consider revisions in corrosion control measurement techniques and criteria.