A modified version of the slope parameter equation for pipelines that incorporates metallic path resistance is presented. Solutions to this expression are compared to ones based upon a first principles based potential attenuation equation. Agreement between the far field potential projected by each was found to be good for anode spacings less than 10,000 m, but the modified slope parameter equation produced conservative far-field potentials for anode spacing less than 20,000 m.
Key Words: Pipelines, cathodic protection, potential attenuation, slope parameter, design.