Miniaturized sector array with additive-manufactured mirror for low diameter pipe inspection

The ultrasonic inspection of low diameter pipes remains challenging, particularly in the power industry where new heater exchanger designs include tight curvatures and severe access restrictions. Moreover, advances in welding techniques require performing not only normal-incidence corrosion maps typical in pipe inspection, but also the more complex weld evaluation procedures that require oblique incidence at different propagation angles and modes. This work presents the design, fabrication and preliminary characterization of a miniaturized sector array for low diameter pipe inspection, with 7.8 mm exterior diameter, 8 sector elements and 2.0 MHz center frequency. A 45° reflector cone was developed by additive manufacturing for obtaining normal incidence at the pipe wall. The additive manufacturing technique allows to easily testing different mirror geometries at low cost, giving more flexibility to the design and validation process. The experimental results include the analysis of the pulse-echo temporal ...