Which type of cathodic protection system must electrically isolate tanks and piping from other metal structures?

Galvanic cathodic protection is a system that involves using sacrificial anodes to prevent corrosion on metal structures, such as tanks and piping. This type of system requires that the tanks and piping be electrically isolated from other metal structures to ensure that the protective current flows through the intended paths.

When tanks and piping are electrically isolated, there is no interference from external metal structures, which might otherwise steal the protective current. This ensures effective cathodic protection by allowing the sacrificial anodes to provide the necessary electrons to protect the steel surfaces from corrosion. Therefore, to implement galvanic cathodic protection effectively, achieving this electrical isolation is a critical requirement.

In contrast, impressed current systems do not rely on sacrificial anodes but instead use an external power source to drive current through the system, which is less dependent on electrical isolation from surrounding metal. Leaching probes and factory-applied coatings do not pertain to cathodic protection but rather address other aspects of corrosion control and tank integrity, further clarifying the specific role of galvanic systems in corrosion prevention.