AC Corrosion Mapping is a non-invasive pipeline inspection technique that uses alternating current (AC) signals to detect, locate, and map external corrosion on buried pipelines.

AC Corrosion Mapping is a non-invasive pipeline inspection technique that uses alternating current (AC) signals to detect, locate, and map external corrosion on buried pipelines. During an AC corrosion survey, a low-frequency AC signal is applied to the pipeline, and variations in electrical resistance along the pipe surface are measured. Areas of active corrosion reduce the metal’s resistance, producing measurable signal changes that are translated into a detailed corrosion map.

This corrosion map gives pipeline operators a visual overview of corrosion location, severity, and extent — enabling data-driven decisions for pipeline maintenance, repair planning, and remaining life assessments. AC Corrosion Mapping is widely used in pipeline integrity management programs and integrates seamlessly with ECDA (External Corrosion Direct Assessment) workflows.

For pipelines that cannot be inspected internally — known as unpiggable pipelines — aboveground techniques like AC Corrosion Mapping and Current Magnetometry Inspection (CMI) provide critical corrosion data without excavation or operational shutdowns.