HDG and Stray Current Corrosion
Does HDG Protect Against Stray Current Corrosion?
Stray current corrosion is a complex corrosion issue where stray electrical currents from external sources result in current flow through a metallic structure that is not intended. Buried or immersed metallic structures such as electrified-transit systems, steel reinforcements of tunnels, underground pipelines, rail fixtures, and guyed communication tower anchors are especially susceptible to corrosion from stray currents. This type of corrosion can occur rapidly depending on its proximity to water or soil properties.
Hot-dip galvanizing can provide these structures with many decades of corrosion protection in atmospheric and soil environments, but it is not a substitute for employing stray corrosion management strategies such as monitoring, impressed current cathodic protection systems, the use of sacrificial anodes, or increased distance between interfering structures. Without multiple methods employed for susceptible structures, it is possible to encounter hot-dip galvanized steel with excellent performance above-ground while stray current corrosion rapidly attacks the local area where an undesired current is exiting the structure. Instead, methods to prevent stray current corrosion should be employed alongside corrosion protection systems or protective coatings such as hot-dip galvanizing.
Stray-current corrosion is a specialized corrosion case, and it is recommended projects with susceptible metal structures involve a corrosion specialist through AMPP (formally NACE International/SSPC) for consulting purposes.
© 2021 American Galvanizers Association. The material provided herein has been developed to provide accurate and authoritative information about after-fabrication hot-dip galvanized steel. This material provides general information only and is not intended as a substitute for competent professional examination and verification as to suitability and applicability. The information provided herein is not intended as a representation or warranty on the part of the AGA. Anyone making use of this information assumes all liability arising from such use.