Dry-Coupled Magnetostrictive-Based Guided Wave Equipment for Pipeline Inspection

A combined method using both liquid couplant and mechanical clamping is proposed for magnetostrictive sensor to inspect large diameter and high temperature pipelines. The tailor-made flexible clamping structure was devised for applying strong pressure onto the MsS strip to ensure that the interaction force between the iron-cobalt alloy strip and tested pipe surface evenly distributes along the circumferential direction. The presented coupling method is unaffected by the pipeline temperature. The MsS employing this coupling method can generate equivalent guided wave energy to that of a MsS pasted onto the pipe surface using epoxy. Then, the presented dry-coupled MsS is applied for practical inspections based on the developed MsTGW inspection system. The experimental result obtained from large diameter and high temperature pipelines show that the dry-coupled MsS-based guided wave technique can locate the positions of the featured structure and defects with an error less than 5.00%. The presented flexible clamping structure has good application prospects because it can be easily installed onto the tested pipeline surface.