An assessment of the present criteria for cathodic protection of buried steel pipelines

An experimental laboratory study has been conducted to assess the criteria for cathodic protection of a buried pipeline. The specific cathodicprotection potential requirements to prevent pitting and general corrosion of steel were determined in six natural soils with various amounts of moisture and oxygen (aerated or deaerated), and were compared to the criteria values of -0.85 V (Cu/CuSO4), 100 mV polarization, 300 mV voltage shift, and Tafel potential. The effects of temperature 600C (1400F) anaerobic bacteria, and steel surface condition (bare or mill scaled) on the specific requirements in selected soils were assessed also. Overall, the research concluded the present criteria were generally valid in concept; however, the critical values for the present criteria could vary with the environment, but with one noted exception. This experimental study concluded that the 100 mV polarization criterion was the most generally valid and applicable criterion