ANORDNING FOR KVALITETSKONTROLL AV ROR MEDELST ULTRALJUD

Immersed testing of a moving tubular part within a tank filled with an acoustic couplant fluid is performed by means of at least one stationary but positionally adjustable ultrasonic emitter-receiver tranducer 22a, 22b of annular design having a flat active face 26a, 26b directed towards a stationary ultrasonic mirror 18, 16. The mirror surrounds the tube and reflects the ultrasonic beam onto the tube wall at a constant angle of incidence. The active transducer face is divided into at least two separate active parts (Figs. 2, 3 not shown) which are excited cyclically and successively in time. The inspection device achieves high signal reproducibility in any angular location of flaws and a substantially enhanced signal-to-noise ratio. Inspection can be by transverse waves A2 or longitudinal waves A1. In the latter case a helical mirror 18 is associated with an effectively spiral transducer (Fig. 3).