Article Periodicals » Materials Evaluation » Article
Monitoring the Growth of Hidden Corrosion Discontinuities in a Pipeline with Complex Geometry Using Torsional Mode Ultrasonic Guided Wave

The peak amplitude of the fundamental torsional mode, T(0,1), ultrasonic guided wave, excited and sensed by commercially available equipment using permanently mounted magnetostrictive transducers, was used to monitor the growth of electrochemically induced, external discontinuities in a steel pipeline (216 mm outside diameter). The pipeline was more than 30.5 m long, had multiple welds and two 90° elbows. Over the course of eight months, two discontinuities, hidden from ultrasonic testing (UT) technicians, grew systematically in both area and depth, providing the opportunity to experimentally evaluate the effects of complex geometry on signal characteristics. Corrosion around a weld was also studied. The obtained results were compared with a surface discontinuity that was unaffected by intermediate welds located between the transducer and the discontinuity. It was found that the effects of multiple welds and an elbow decreased the sensitivity for discontinuity growth monitoring by a factor of less than two. This was established by examining the scaling of discontinuity signal peak heights against a weld peak instead of using a conventional distance-amplitude-correction (DAC) curve to account for material attenuation, by comparing the signals from a discontinuity viewed along the forward and the reverse direction, and by allowing the discontinuities to change in all three dimensions in the course of this monitoring effort. This controlled study for discontinuity growth monitoring can be useful to guide efforts on discontinuity growth monitoring of complex pipelines in the field.

Alleyne, D. N. and P. Cawley, “Long Range Propagation of Lamb Waves in Chemical Plant Pipework,” Materials Evaluation, Vol. 45, No. 4, 1997, pp. 504–508. Demma, A., P. Cawley, M. Lowe and A. Roosenbrand, “The Reflection of the Fundamental Torsional Mode from Cracks and Notches in Pipes,” Journal of the Acoustical Society of America, Vol. 114, No. 2, 2003, pp. 611–625. Demma, A., P. Cawley, M. Lowe, A. Roosenbrand and B. Pavlakovic, “The Reflection of Guided Waves from Notches in Pipes: A Guide for Interpreting Corrosion Measurements,” NDT & E International, Vol. 37, No. 3, 2004, pp. 167–180. Demma, A., P. Cawley, M. Lowe and B. Pavlakovic, “The Effect of Bends on the Propagation of Guided Waves in Pipes,” Journal of Pressure Vessel Technology – Transactions of the ASME, Vol. 127, No. 3, 2005, pp. 328–335. Kwun, H., S. Y. Kim and G. M. Light, “The Magnetostrictive Sensor Technology for Long Range Guided Wave Testing and Monitoring of Structures,” Materials Evaluation, Vol. 61, No. 1, 2003, pp. 80–84, Kwun, H., S. Y. Kim and A Crouch, “Method and Apparatus Generating and Detecting Torsional Waves for Long Range Inspection of Pipes and Tubes,” U.S. Patent 6624628, 2003. Kwun, H., J. Crane, S. Y. Kim, A. Parvin and G. M. Light, “A Torsional Mode Guided Wave Probe for Long range In-bore Testing of Heat Exchanger Tubing,” Materials Evaluation, Vol. 63, No. 4, 2005, pp. 430–433. Ledesma, V., E. Perez Baruch, A. Demma and M. J. S. Lowe, “Guided Wave Testing of an Immersed Gas Pipeline,” Materials Evaluation, Vol. 67, No. 2, 2009, pp. 102–115. Liu, J. M. and C. E. Davis, “Laboratory Assessment of Ultrasonic Guided Wave Technology for Corrosion Damage Detection in Piping with a Deck Joint and an Elbow,” Technical Report NSWCCD-61-TR-2005/26, April 2006. Liu, J. M. and C. P. Nemarich, “Remote NDE Technology for Inaccessible Shipboard Piping Inspection,” Journal of Failure Analysis and Prevention, Vol. 8, No. 2, 2008, pp. 193–198. Mu, J., M. J. Avioli, and J. L. Rose, “Long-range Pipe Imaging with a Guided Wave Focal Scan,” Materials Evaluation, Vol. 66, No. 6, 2008, pp. 663–666. Rose, J. L., Ultrasonic Waves in Solid Media, Cambridge University Press, New York, New York, 1999. Rose, J. L., Z. Sun, P. J. Mudge and M. J. Avioli, “Guided Wave Flexural Mode Tuning and Focusing for Pipe Testing,” Materials Evaluation, Vol. 61, No. 2, 2003, pp. 162–167. Rose, J. L., L. Zhang, M. J. Avioli and P. J. Mudge, “A Natural Focusing Low Frequency Guided Wave Experiment for the Detection of Defects Beyond Elbows,” Journal of Pressure Vessel Technology, Vol. 127, No. 3, 2005, pp. 310–316. Rose, J. L., J. Mu and J. K. Van Velsor, “New Directions in Guided Wave Pipe Testing,” Materials Evaluation, Vol. 65, No. 4, 2007, pp. 375–378.
Usage Shares
Total Views
29 Page Views
Total Shares
0 Tweets
0 PDF Downloads
0 Facebook Shares
Total Usage