Reducing false alarms in guided waves structural health monitoring of pipelines: Review synthesis and debate

Guided waves based structural health monitoring systems have been proposed to ensure reliability and structural integrity of pipelines. These systems are designed with permanently attached transducers that are able to detect automatically early state damage that could occur during the lifetime of a pipeline. Actually, the transducers are responsible for generating ultrasonic guided waves signals which propagate through the pipeline and interact with damage. Therefore, the interpretation of the received signals leads to ascertain if the pipeline is damaged or not. However, these signals are very complicated and may contain not only information about damage, but also the effects of environmental and operational conditions (temperature, flow rate etc.) and the effects of the transducers issues (fracture, debonding etc.). If these effects are not taken into account they would result in false indication of damage (false alarm). This paper presents a literature synthesis review of different methods and strategies that have been developed to reduce false alarms during in-situ monitoring of pipelines using guided ultrasonic waves technique. A critical view of each method is provided to determine which method is suitable for which context. Basing on this review and the field experience of the authors, recommendations are provided in order to help designers and practitioners in their decision-making. Although the paper focuses on pipeline safety, the recommendations could be applicable to other structures such as (rails, plates, cables etc.).