NACE SP0207-2026

Performing Close-Interval Potential Surveys and DC Surface Potential Gradient Surveys on Buried or Submerged Metallic Pipelines

This standard practice presents procedures for performing close-interval direct current (DC) structure-to-electrolyte potential surveys, DC surface potential gradient surveys, and hybrid surveys such as trailing-wire direct current voltage gradient (DCVG) surveys or intensive measurement surveys, on buried or submerged metallic pipelines. Cell-to-cell surveys used to evaluate coating effectiveness are described in other AMPP publications. This standard is intended for use by corrosion control personnel involved with operating pipelines, contractors performing close-interval surveys (CIS) and other surveys, corrosion professionals interpreting CIS and other survey data, and regulatory agencies. Included are definitions, pre-job considerations, instrumentation and equipment guidelines, methods for voltage drop correction, pipe location and marking procedures, survey procedures, hybrid survey procedures, offshore and dynamic stray-current survey procedures, cell-to-cell surface potential gradient surveys, and data validity and post-job considerations. For accurate and correct application, this standard must be used in its entirety. Using or citing only specific paragraphs or sections can lead to misinterpretation and misapplication of the recommendations and practices presented. Specific practices are not designated for every situation because of the complexity of conditions to which buried or submerged piping systems are exposed.