Title
Ultrasonic multi-skip tomography for pipe inspection
Author
Volker, A.W.F.
Vos, H.J.
Hunter, A.J.
Lorenz, M.
Publication year
2012
Abstract
The inspection of wall loss corrosion is difficult at pipe support locations due to limited accessibility. However, the recently developed ultrasonic Multi-Skip screening technique is suitable for this problem. The method employs ultrasonic transducers in a pitch-catch geometry positioned on opposite sides of the pipe support. Shear waves are transmitted in the axial direction within the pipe wall, reflecting multiple times between the inner and outer surfaces before reaching the receivers. Along this path, the signals accumulate information on the integral wall thickness (e.g., via variations in travel time). The method is very sensitive in detecting the presence of wall loss, but it is difficult to quantify both the extent and depth of the loss. If the extent is unknown, then only a conservative estimate of the depth can be made due to the cumulative nature of the travel time variations. Multi-Skip tomography is an extension of Multi-Skip screening and has shown promise as a complimentary follow-up inspection technique. In recent work, we have developed the technique and demonstrated its use for reconstructing high-resolution estimates of pipe wall thickness profiles. The method operates via a model-based full wave field inversion; this consists of a forward model for predicting the measured wave field and an iterative process that compares the predicted and measured wave fields and minimizes the differences with respect to the model parameters (i.e., the wall thickness profile). This paper presents our recent developments in Multi-Skip tomographic inversion, focusing on the initial localization of corrosion regions for efficient parameterization of the surface profile model and utilization of the signal phase information for improving resolution.
Subject
Corrosion
Multi-Skip
Support
Tomography
Wall Thickness Profile
Wave Field Inversion
Industrial Innovation
Fluid Mechanics Chemistry & Energetics ; Physics & Electronics
PID - Process & Instrumentation Development ; AS - Acoustics & Sonar
TS - Technical Sciences
To reference this document use:
http://resolver.tudelft.nl/uuid:15926b99-aa85-46c4-af7d-fd7737d61122
TNO identifier
462177
ISBN
9780735410138
ISSN
0094-243X
Source
38th Annual Review of Progress in Quantitative Nondestructive Evaluation, QNDE, 17-22 July 2011, Burlington, VT, USA, 1430 (1430), 785-792
Series
AIP Conference Proceedings
Document type
conference paper