This paper presents case histories where polyethylene encasement and cathodic protection have been used together to effectively control external corrosion of ductile iron pipelines in very corrosive soils. This practical and cost effective strategy capitalizes on the synergistic effects of these two established corrosion control techniques. Pipeline designs dating back to at least the 1970s for over 300 miles of construction have included this corrosion control methodology. The case histories include both impressed current and galvanic current protection. Non-invasive surface electrical potential measurements and record reviews were used to determine locations for excavations to inspect the condition of the pipe and polyethylene encasement.
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