Evaluation of Cathodic Protection Effectiveness on Buried Gas Pipelines in Plateau State

Cathodic protection (CP) is a widely adopted electrochemical technique for mitigating external corrosion on buried metallic gas pipelines. This study evaluates the effectiveness of cathodic protection systems installed on buried natural gas pipelines in Plateau State, particularly along the spur pipeline serving Jos industrial users and the domestic distribution network in Bukuru. The research employs a CP survey methodology, conducting close interval potential surveys (CIPS), direct current voltage gradient (DCVG) surveys, and above-grade potential measurements at test stations along the studied pipeline sections. Survey results are compared against the widely adopted NACE International SP0169 criterion of minus 850 millivolts (Cu/CuSO4) as the minimum protection potential. The study further investigates the adequacy of CP power units, the condition of pipeline coating used as the primary corrosion barrier, and the impact of soil resistivity variations across Plateau State's diverse geological terrain on CP current requirements. Findings indicate that approximately 30 percent of tested pipeline segments exhibit potentials more positive than the protection criterion, suggesting inadequate cathodic protection in these areas, with the highest deficiency rate in sections crossing high-resistivity lateritic soils. Recommendations include rectifier output upgrades, installation of additional sacrificial anodes at unprotected segments, and adoption of an annual CP survey schedule. This study advances cathodic protection practice for Nigeria's expanding inland gas pipeline network. Keywords: cathodic protection, buried pipeline, Plateau State, corrosion, CIPS survey.