This paper represents the consensus reached during a panel discussion held at the CEOCOR International Congress in Stockholm, Sweden, June 2–5, 2015. It reviews the state‐of‐the‐art about the generally accepted understanding of the working mechanism of cathodic protection of ground buried steel structures. Based on this, limitations of existing protection criteria are discussed, particularly the difficulties related to measuring and interpreting current‐applied potentials, instant‐off potentials, and IR‐free potentials. A set of protection criteria and their interpretation in accordance with the understanding of the working mechanism of cathodic protection is proposed. The main idea is that it is distinguished between the following two situations: 1) conditions that permit an increase in pH at the steel surface as a result of the applied protection current (good bedding conditions inhibiting convection) and thus provide corrosion protection by achieving passivity; and 2) situations where this is not possible (e.g. in streaming soft water) or where it is unknown if this is possible, and thus effective corrosion protection can only be achieved by polarizing the steel into the immunity zone.
ASTM Subcommittee G01.11 on Electrochemical Measurements in Corrosion Testing has conducted round-robin testing on the reproducibility of cyclic potentiodynamic polarization measurements for determining susceptibility to localized corrosion. This work was used in the development of a practice that provides a standard experimental procedure for conducting these tests. This paper presents the experimental procedure and results of the round-robin tests with statistical analysis of the data. The reproducibility of the measurements and sources of error are discussed.
ASTM Subcommittee G01.05 on Laboratory Corrosion Tests currently has nine task groups working on the development of new standards and revisions of its existing 13 standards. Revisions to existing test methods and practices often have been overlooked, resulting in confusion regarding compliance with the standards. This paper highlights the changes that have been made in existing standards over the last ten years. Problems and misconceptions associated with existing standards such as the salt spray test are discussed.
Particular attention is paid to corrosion testing of electronic materials and modified salt spray testing. The former is the topic of a draft proposal in ISO, while standardization of the latter has been fragmented. The need for a coherent approach to standardization of salt spray tests is discussed. Round-robin data showing the interlaboratory reproducibility of the salt spray test are presented.
Automobile manufacturers utilize a variety of metals to build a product that meets numerous functional and cosmetic demands. Since the auto environment is highly corrosive, they must consequently deal with galvanic corrosion problems. This paper describes some of the galvanic couples on automobiles, such as trim on painted auto-body steel, dissimilar metal fasteners, electroplated bumpers, galvanized steel, and dissimilar cooling system components. The resulting problems and mitigative measures for controlling galvanic corrosion are presented.
The corrosivity of engine antifreeze coolants depends on many factors including inhibitor concentration. Degradation of these antifreeze inhibitors occurs with time in service and therefore leads to increased corrosivity. This paper describes a low cost coolant sensor capable of detecting the corrosivity of engine coolant in-situ. The system is based on electrochemical principles and consists of a sensing probe, electronics package, and an indicating device. Electrochemical theory and supporting data for the system will be presented.
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