Abstract: In the periodical inspection of the connecting pipe bend from economizer to steam drum, it was found that the reflection signal exceeds the specified value. Using A scan pulse echo technology, the flaw echo could be found, but the exact defect information could not be judged. Using the TOFD technique to recheck, the defect could not be detected. When using the ultrasonic wave phased array method, the defect was detected easily. Based on the detection results of ultrasonic wave phased array method, the exact defect information could be obtained.

Key words: A scan pulse echo method, time of flight diffraction technique, ultrasonic wave phased array method, sector scan, B scan