The torsional mode of guided wave, T(0,1), has been applied to detect discontinuities in pipelines, especially in the cases of coated, elevated and buried pipes. The signals of minor corrosions would be covered by the noise, unfortunately, because the coated material and buried medium always induce a strong attenuation of the guided wave. The main objective of this study was to discuss the effect of bitumen coating on guided wave tests by the experimental and signal processing techniques, based on the use of continuous wavelet transform. The experiments were first performed to collect the reflected signal of the discontinuities on two 152.4 mm steel pipes. The results showed that the bitumen coating seriously attenuated the signals of every discontinuity on the test pipes. The continuous wavelet transform was then used to perform a distance-frequency analysis in order to achieve the success of the minor discontinuity detection. In conclusion, the discussion of the effect of the bitumen coating on guided wave propagation and useful signal processing techniques will help to increase the sensitivity of discontinuity detection on coated pipe.
Alleyne, D. N., B. Pavlakovic, M. J. S. Lowe and P. Cawley, “Rapid Long
Range Inspection of Chemical Plant Pipework Using Guided Waves,”
Insight, Vol. 43, No. 2, February 2001, pp. 93–96.
Alleyne, D. N., T. Vogt and P. Cawley, “The Choice of Torsional or Longitudinal
Excitation in Guided Wave Pipe Inspection,” Insight, Vol. 51, No. 7,
July 2009, pp. 373–377.
Barshinger, J. N. and J. L. Rose, “Guided Wave Propagation in an Elastic
Hollow Cylinder Coated with a Viscoelastic Material,” IEEE Transactions
on UFFC, Vol. 51, No. 11, November 2004, pp. 1547–1556.
Cawley, P., M. J. S. Lowe, D. N. Alleyne, B. Pavlakovic and P. Wilcox,
“Practical Long Range Guided Wave Testing: Applications to Pipes and
Rail,” Materials Evaluation, Vol. 61, No. 1, January 2003, pp. 66–74.
Cheng, J. W., S. K. Yang and B. H. Li, “Torsional Guided Wave Attenuation
in Buried Pipe,” Materials Evaluation, Vol. 64, No. 4, April 2006,
Demma, A., D. N. Alleyne and B. Pavlakovic, “Testing of Buried Pipelines
Using Guided Waves,” Third Middle East Non-Destructive Testing Conference
and Exhibition, Manama, Bahrain, 27–30 November 2005.
Demma, A., P. Cawley, M. J. S. Lowe and A. G. 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, August
2003, pp. 611–625.
Demma, A., P. Cawley, M. J. S. Lowe, A. G. 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. 2, April 2004, pp. 167–180.
Rose, J. L., D. Jiao and J. Spanner, “Ultrasonic Guided Wave NDE for
Piping,” Materials Evaluation, Vol. 54, No. 11, November 1996,
Guided Ultrasonics, Ltd., Wavemark G3 Procedure Based Inspector Training
Manual, Version 1.0, Guided Ultrasonics, Ltd., Nottingham, England,
Leymarie, N. and S. Baste, “Guided Waves and Ultrasonic Characterization
of Three-dimensional Composites,” Review of Progress in Quantitative
Nondestructive Evaluation, Vol. 19, New York, Plenum, May 2000,
Marzani, A., E. Viola, I. Bartoli, F. Lanza di Scalea and P. Rizzo, “A Semianalytical
Finite Element Formulation for Modeling Stress Wave Propagation
in Axisymmetric Damped Waveguides,” Journal of Sound and
Vibration, Vol. 318, No. 3, 2008, pp. 488–505.
Mu, J. and J. L. Rose, “Guided Wave Propagation and Mode Differentiation
in Hollow Cylinders with Viscoelastic Coatings,” Journal of the
Acoustical Society of America, Vol. 124, No. 2, 2008, pp. 866–874.
Mudge, P. J., “Field Application of the Teletest Long Range Ultrasonic
Testing Technique,” Insight, Vol. 43, No. 2, February 2001, pp. 74–77.
Nunez Ledesma, V. M., E. Perez Baruch, A. Demma, and M. J. S. Lowe,
“Guided Wave Testing of an Immersed Gas Pipeline,” Materials Evaluation,
Vol. 67, No. 2, February 2009, pp. 102–115.
Onsay, T. and A. G. Haddow, “Wavelet Transform Analysis of Transient
Wave Propagation in a Dispersive Medium,” Journal of the Acoustical Society
of America, Vol. 95, No. 3, 1994, pp. 1441–1449.
Pavlakovic, B., M. J. S. Lowe, D. N. Alleyne and P. Cawley, “Disperse: A
General Purpose Program for Creating Dispersion Curves,” Review of
Progress in Quantitative Nondestructive Evaluation, Vol. 16, New York,
Plenum, 1997, pp. 185–192.
Rizzo, P., I. Bartoli, A. Marzani, and F. Lanza di Scalea, “Defect Classification
in Pipes by Neural Networks Using Multiple Guided Ultrasonic Wave
Features Extracted After Wavelet Processing,” Journal of Pressure Vessel
Technology, Vol. 127, No. 3, 2005, pp. 294–303.
Simonetti, F., “Lamb Wave Propagation in Elastic Plates Coated with
Viscoelastic Materials,” Journal of the Acoustical Society of America, Vol. 115,
No. 52, 2004, pp. 2041–2053.
Simonetti, F. and P. Cawley, “A Guided Wave Technique for the Characterization
of Highly Attenuative Viscoelastic Materials,” Journal of the
Acoustical Society of America, Vol. 114, No. 1, July 2003, pp. 158–165.
Simonetti, F. and P. Cawley, “On the Nature of Shear Horizontal Wave
Propagation in Elastic Plates Coated with Viscoelastic Materials,” Proceedings
of the Royal Society of London A, Vol. 460, No. 2048, 8 August 2004,
Siqueira, M. H. S., C. E. N. Gatts, R. R. da Silva and J. M. A. Rebello, “The
Use of Guided Waves and Wavelets Analysis in Pipe Inspection,” Ultrasonics,
Vol. 41, No. 10, May 2004, pp. 785–797.
Yang, W. X., “A Natural Way for Improving the Accuracy of the Continuous
Wavelet Transforms,” Journal of Sound and Vibration, Vol. 306,
September 2007, pp. 928–939.