In-Line Inspection Using Combined Technologies - Magnetic Flux Leakage and Ultrasonic Testing and their Advantages
Proceedings Publication Date
Both Magnetic Flux Leakage (MFL) and Ultrasonic Testing (UT) are established technologies in the In-line Inspection (ILI) industry. The MFL method is understood as a versatile and robust method to determine the geometry of metal loss found in both liquid and gas pipelines, while the UT method allows a highly accurate direct measurement of the pipeline wall thickness. The paper will present a solution, developed by ROSEN, combining both technologies on a single in-line inspection tool. Fortunately, the combination of the two methods is complementary to the restrictions of each other. Furthermore the overall scope of the inspection is enlarged. General wall thinning and largely corroded areas are accurately and reliably scanned with the UT unit, while very detailed information about pitting corrosion is obtained from the MFL measurement. Blind spots of echo loss, occasionally observed in the UT data, are compensated by the more robust measurement from the MFL sensors. This is due to the fact that a magnetic pattern is typically larger in dimension than the anomaly that caused it, greatly improving the probability of detection.