Detection of Crack-Related Features Within Dented Pipe Using Electromagnetic Acoustic Transduction (EMAT) Technology

Mechanical damage has been identified as a significant integrity threat within the Oil & Gas pipeline industry. In addition to deformation, associated secondary pipeline damage may also consist of coating removal, metal removal and cold working of the underlying metal that may result in cracking within the dented area. Detection of cracks within dented areas of the pipe using conventional Ultrasonic Technology (UT) and Magnetic Flux Leakage (MFL) In-line Inspection (ILI) technologies has been of limited success due to the variety of possible feature expressions, sensor design and arrangements, and the related complexity within the underlying physics for detection and characterization. Previous studies have shown the feasibility of Electro Magnetic Acoustic Transduction (EMAT) technology for detecting and characterizing crack related indications within dents on liquid pipelines. This study expands upon experimental investigations using pull through ILI tests on manufactured dents where machined linear indications (notches) were introduced into the dents. In this paper, the performance of EMAT technology for detection and characterization of crack related features in liquids pipelines under real operating conditions is presented. EMAT data were combined with high resolution caliper data, ultrasonic crack inspection data and dent strain assessment data, to demonstrate the EMAT capabilities to enhance pipeline integrity management of dents. Results of field non-destructive examinations are compared to EMAT predicted values to assess the performance of this technology. This study presents a supplementary method of detecting and mitigating coincidental crack related features with dents on liquids pipelines, further enhancing the safety and improving the integrity management of pipelines.