Magnetostrictive Ultrasonic Torsional Wave Detection Method for High-Density Polyethylene Pipe Weld Status

High-Density Polyethylene (HDPE) pipelines, renowned for their outstanding mechanical properties, have found extensive applications in the fields of gas and water supply. Traditional methods for HDPE inspection require complex installation and cleaning procedures, making in-service inspection challenging. This paper proposes a detection method utilizing flexible magnetostrictive transducers (FMsT) to excite ultrasonic torsional waves and applies it to the assessment of the welding status of HDPE pipes. The excitation of ultrasonic torsional waves is theoretically analyzed, exploring the viscoelastic HDPE pipe torsional wave propagation model and analyzing the theoretical features of attenuation and dispersion. Taking this as a theoretical basis, FMsT in HDPE pipes was designed, to excite ultrasonic torsional waves and propagate them along the pipes. This paper investigates the operational principles of FMsT, identifying HDPE defect characteristics through the reception of reflected echoes and transmitted waves. The experiments demonstrate that FMsT can successfully excite and detect ultrasonic torsional waves in HDPE pipes. It can effectively identify and detect the size and distinguish the localization of welding defects with a minimum detection length of 0.5 mm, validating the feasibility of this method.