Criteria for Cathodic Protection (Coated versus Bare Pipelines)

1. A pipe-to-soil potential of -0.85 volts versus a Cu-CuSO₄ electrode indicates satisfactory cathodic protection.

2. The -0.85 criteria as well as a potential shift of -300 mV vs a Cu-CuSO₄ electrode is used for bare pipelines. It is also suggested that a -100 mV shift of potential in bare pipelines indicates a good degree of cathodic protection.

3. A potential of -0.95 volts with respect to a Cu-CuSO₄ electrode indicates a good degree of cathodic protection in anaerobic soils containing sulphate reducing bacteria.