Recent Achievements in Sizing and Characterization of Weld Defects with Pulse Echo,TOFD and Phased Array in the Frame of ASME and EN Standards

摘要

This paper highlights the results in sizing and characterization of discontinuities in heavy wall thickness welds. The results come from more than 50 years of experience in ultrasonic examination of welds. The discover and application of the diffracted echo in Pulse Echo and Phased Array has led to a great advance in sizing discontinuities smaller than the crystal size with an accuracy ranging between 0.2 to 0.5 mm. In addition, the ratio between the diffracted echoes has been experimental demonstrated to be a very helpful criterion to differentiate planar from volumetric discontinuities. Two other items have been included in the paper, the classification of the TOFD image to improve the reliability and POD (Probability of detection) of TOFD technique, and the importance of focusing in the near field of Phased Array probe. To achieve and verify the focusing of the beam a new test block named IIW-V3/PA has been designed with three path distances: 25, 50 and 100 mm.