Pipe Disbondment Detection and Coating Assessment Using the Dynamic Wavelet Fingerprinting

Existing pipe inspections ae incapable of reliably detecting coating disbonds. Conventional above ground surveys cannot detect disbonds because of shielding conditions, and traditional guided wave inspection systems are unable to reliably detect subtle non-axisymmetric flaws. Finally, most of the advanced ultrasound technology in industry has been focused on inline inspection systems which are inappropriate for un-pigable lines. We have demonstrated previously the ability to extract information about multiple modes from the guided wave signals using the dynamic wavelet fingerprinting technique. We propose here a different inspection technique that uses normal incidence transducers to generate feature-rich multi-mode signals as opposed to single axisymmetric or flexural modes. A large portion of this work will be focused on numerically and analytically exploring the complicated propagation of the guided waves in different types of coatings, and scattering from disbondment flaws. Then, with the DWFP multi-mode detection technique and knowledge gained from the numerical and analytical studies, individual modes can be monitored and any changes can be used to detect and localize subtle flaws in complex piping systems.