What metal is commonly used for sacrificial anodes on underground equipment?

Zinc is commonly used for sacrificial anodes on underground equipment because of its electrochemical properties. When zinc is used, it acts as a more reactive metal compared to the materials it is protecting, such as steel or iron. This means that zinc will corrode preferentially, sacrificing itself to protect the underground structures from corrosion. This process is called cathodic protection, where the sacrificial anode creates a protective layer around the equipment, preventing rust and deterioration.

Zinc's effectiveness in this role is due to its ability to create a more favorable electrochemical environment. When zinc is exposed to moisture and soil, it oxidizes and provides electrons to the surrounding metal structures, mitigating corrosion. This property makes zinc a go-to choice for applications like pipelines, tanks, and other underground installations where corrosion is a significant concern.

Copper and aluminum, while they have their own uses in electrical and structural applications, do not provide the same level of sacrificial protection as zinc. Iron, although it can be corroded, does not serve the purpose of a sacrificial anode since it is often the metal needing protection rather than the one providing it.