NACE SP 0169:2013

Cathodic potential (CP) criteria have been used as a recommended minimum requirement for controlling external corrosion of buried or submerged steel piping systems. A critical review of CP criteria in five international CP standards and historical publications was undertaken. Discrepant and sometimes conflicting CP criteria were found among the CP standards. This may confuse practitioners and lead to misdirected decisions. The impact on the operating cost can also be significant when an inappropriate criterion is used such as the ?850 mV on- vs. off-potential criterion in areas with current interferences. This discrepancy associated with diverse and sometimes conflicting CP criteria may be attributed to both the lack of sufficient field data for validating the criteria and the lack of clarity with the fundamentals behind the criteria. In the first part of a three-part paper the historical versions of the CP criteria in NACE Standard RP/SP 0169 were reviewed the criteria in five international CP standards were compared and an understanding of the correlation between CP criteria and theory was provided.