PURPOSE: To detect a defect on a nozzle part, especially on the inside part of the nozzle, with high SN ratio by using a longitudinal wave for a nozzle having a clad in its inside and a transversal wave for a nozzle having no clad.
CONSTITUTION: In the nozzle having the clad 14, an ultrasonic probe 1 arranged on the outside saddle part of the nozzle detects a flaw by using a longitudinal wave 10, and at the same time, a transversal wave beam 11 is generated with a refractive angle of about 1/2 the longitudinal wave, reflected at the boundary part 12 with the clad and appears as a noise echo. The noise echo is delayed from the reflected wave based upon the longitudinal wave beam 10 from the inside defect 13 to reach the probe 1. Therefore, the defect can be discriminated. In case of flaw detection by the nozzle part having no clad 14, there is no noise echo from the boundary part 12 with the clad, so that the use of the transversal wave generates high SN ratio.
KANDA MIKIO
KAKINUMA YUKIO
TAKAKU KAZUO
HITACHI ENG CO LTD
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