Fig. 1. Schematic diagram of the curved pipeline

Fig. 2. Schematic diagram of the curved pipeline defects

Fig. 3. Experimental device

Fig. 4. Position of the probe. (a) Position 1; (b) position 2; (c) position 3

Fig. 5. Two-dimensional maximum amplitude image of the curved pipeline. (a) Position 1; (b) position 2; (c) position 3

Fig. 6. Dynamic image of ultrasonic propagation of the curved pipeline. (a) Position 1; (b) position 2; (c) position 3

Fig. 7. Animation of ultrasonic propagation in the visualized range of the curved pipeline. (a) 14.3 μs; (b) 16.8 μs; (c) 19.8 μs; (d) 24.5 μs

Fig. 8. Time domain signal diagram

Fig. 9. Spectrum distribution diagram

Fig. 10. Defect position pointed by light guide