Long range guided wave testing of pipe is becoming commonplace today in serving as an excellent screening tool. Recent concerns, however, are associated with reduced penetration power due to viscoelastic coatings and soil loading of buried pipes. This paper discusses the problem and some new approaches to improve penetration power concerns via phased array focusing, natural focusing and frequency tuning. Preliminary experimental efforts will be presented for various coatings and soil types showing an influence on axisymmetric wave propagation. Discussions of instrumentation and actuator and sensor parameters along with a few sample results on discontinuity detection and sizing are presented.
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