Hydrogen‐Assisted Cracking on Onshore Pipelines Driven by Cathodic Protection

This chapter presents a root cause analysis of an in-service rupture and leaks in an onshore transmission pipeline, identifying hydrogen-assisted cracking (HAC) as the primary mechanism. It also shows similar subcritical cracks found in other onshore pipelines, where the aged defective coating and the consistently negative pipe-to-soil CP potentials drove the HAC-related cracking. The study challenges prevailing assumptions about Near-Neutral pH SCC (NNpHSCC) by linking axial, circumferential, and spiderweb cracks to HAC and HIC. It also explores the potential effects of CP-related hydrogen generation in the growth of other types of cracking, including High pH SCC. Historical data from global cases, including Europe, South America, and North America, further underscore the impact of CP system operations on hydrogen generation. The findings advocate for reevaluating the SCC assumptions when crack fields are found in excavations, emphasizing the need for enhanced RCA protocols to ensure the identification of the actual integrity threat.