Development of a Crimped Torsional Guided Wave Magnetostrictive Transducer (MsT) for Structural Monitoring of High-Temperature Pipelines

High-temperature pipelines are highly susceptible to damage under harsh operational conditions, so it is necessary to carry out robust structural monitoring for the purpose of preventing catastrophic accidents. Although conventional guided wave transducers have been applied in industrial monitoring, their application scope is constrained by insufficient temperature resistance and inapplicability to high-temperature environments. Here, we presented a novel crimped magnetostrictive transducer (MsT) for sustained guided wave monitoring in high-temperature pipelines. In the transducer, a crimped iron-cobalt alloy strip wound with a high-temperature coil was introduced as the core sensing element so as to ensure stable magnetization and coupling under high temperatures. The magnetostrictive transduction theory and the finite element simulation were coupled to investigate the generation mechanism and defect detection sensitivity of torsional guided waves. Then, the performance of the developed transducer was verified through a series of experiments, but its conversion efficiency and mode purity still showed high stability under high-temperature conditions (up to $540~^{\circ }$ C). During the 60-h high-temperature monitoring experiment, the transducer exhibited operational durability under the successfully identified preset conditions. With high-temperature performance and operational applicability, this transducer shows great engineering potential in petrochemical and nuclear industries.