When assessing pipeline integrity by External Corrosion Direct Assessment or Stress Corrosion Cracking Direct Assessment, close interval potential surveys are the most useful Indirect Inspection technique. Accurate measurements are imperative. When potentials are measured with industry standard copper / copper sulfate half cells placed on pavement above a buried pipeline, errors are introduced in the readings. On concrete surfaces, these errors can make the potential appear to be more negative by as much as 250 mV. Where an ECDA or SCCDA project is performed on a pipeline segment under pavement, and close interval, pipe-to-soil potential measurements are chosen as one of the indirect inspection tools, the pavement should be drilled to facilitate half cell contact with the underlying soil.

Subject
Indirect inspection, External corrosion direct assessment, Asphalt, Pipe to soil potential, Stress corrosion cracking direct assessment, Pipelines, Copper sulfate, Potential measurements, Half cell potential, Soil, Half cells, Concrete, Electrode potential
Keywords:
Direct Assessment, External Corrosion Direct Assessment, ECDA, Stress Corrosion Cracking Direct Assessment, SSCDA, Indirect Inspections, Pipe-to Soil Potentials, Pavement, Concrete, Asphalt
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2009
Association for Materials Protection and Performance (AMPP)
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