Unlike traditional ultrasonic NDE methods, guided wave inspections are able to cover tens of meters along a pipeline from a single measurement position. Structural health monitoring (SHM) makes use of repeated measurements of the same pipeline section to investigate the change of its properties over time

and to study the appearance and growth of defects, such as corrosion patches or cracks. Measurements for SHM are collected using permanently installed monitoring systems (PIMS) which unlike conventional guided wave sensors stay attached to the pipeline over their lifetime.

Unfortunately, changing environmental conditions, such as temperature, produce changes in the guided wave propagation that need to be corrected for in order to identify changes caused by the appearance or growth of defects. In this project a number of temperature compensation techniques are being developed and evaluated. The focus is also on the development of automated statistical methods for change detection that can be implemented in the PIMS to fully automate the evaluation of the collected signals. Once fully developed, these systems will allow detecting and tracking the growth of defects significantly smaller than those targeted with the conventional one-off inspection approach. Also, both temperature compensation and change detection algorithms will benefit other applications based on either ultrasonic bulk waves or guided waves.