CP Evaluation on Horizontal Directionally Drilled Pipeline Crossing

Cathodic protection (CP) is essential for horizontal directional drilling (HDD) pipeline crossings because coating damage commonly occurs during pullback installation. To date, no unified industry consensus exists on CP criteria and field testing methods for HDD pipeline crossings. This study establishes a full-scale field-testing method for buried HDD pipeline crossings at varying depths. Reduced oxygen at greater depths lowers corrosion potential, while oxygen concentration cells emerge between shallow and deep pipe sections. Lab tests confirm that depleted oxygen and sulfate-reducing bacteria drastically exacerbate corrosion. The conventional CP criterion of −850 mV CSE is insufficient for these harsh conditions. A minimum potential of −950 mV CSE is therefore recommended.