Post Assessment of Ultrasonic Crack Detection Inline Inspection Data

The information supplied from inline inspection data is often used by pipeline operators to make mitigation and/or remediation decisions based on integrity management program requirements. It is common practice to apply industry accepted remaining strength pressure calculations (i.e. B31G, 0.85 dl, effective area) to the data analysis results from an inline inspection survey used for the detection and characterization of metal loss. Similar assessments of data analysis results from an ultrasonic crack detection survey require expert knowledge in the field of fracture mechanics and, just as importantly, require knowledge to understand the limitations of shear wave ultrasonic technology as applied to an inline inspection tool. Traditionally, crack-like and crack-field features have been classified with a maximum depth distributed over the entire length of the feature; crack-field features also have width reported. In an effort to provide further prioritization, techniques such as “longest length” or “interlinked length” [1] have been employed. More recently, an effort has been made to provide a depth profile of the crack-like or crack-field feature using the ultrasonic crack detection data analysis results. This presentation will discuss the advantages of post assessment of ultrasonic crack detection data analysis results to aid in the evaluation of pipeline integrity and discuss the limitations of advanced analysis techniques. Additionally, the potential for new inline inspection ultrasonic technologies which lend themselves to more accurate data analysis techniques will be reviewed.