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Corrosion


On a roof with copper flashing secured by galvanized steel nails, which metal will corrode the more anodic metal over time as the roof is exposed to rain water?

A. copper flashing
B. galvanized nails
C. neither, the metals are not dissimilar
D. both will equally corrode in contact

AnswerA. copper flashing, more noble and cathodic, will corrode the galvanized nails as electrolytic rainwater is introduced. Contact between 2 metals at different ends of the galvanic scale should be avoided, or non-conductive coatings or materials could separate them.
ARE 4.0 exam prep: BDCS

Resource tip: Read about galvanic action at archtoolbox.com

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