Mapping Stress Corrosion Cracks Using Eddy Current Array Sensors

Rapid and reliable in-the-ditch characterizing and assessment of SCC on natural gas and hazardous liquids pipelines, identified through Integrity Assessment methods or through integrity rehabilitation and maintenance work, continues to be a challenge. Determining SCC severity and making reliable remaining pipe strength predictions requires as a minimum, crack length and crack depth be known. Detailed assessment of crack colonies also requires knowledge of the spacing and relationship of one crack to another. This paper describes the results of a Joint Industry Project (JIP) that comprised of a comparative study of the performance of the Eddy Current Array Sensors relative to the current industry standard of Magnetic Particle Inspection (MPI) for the detection of Stress Corrosion Cracks (SCC) in pipeline steel. The purpose of this study was to qualify the eddy current sensor as an applicable alternative to current practices, given the increasing need for quantifiable results and for analytical capabilities to assess SCC indications.