Preparatory Notes for ASNT NDT Level III Examination - Ultrasonic Testing, UT

TOFD is deployed by scanning the weld with a semiautomatic or fully
automatic scanner. Scan settings are set to determine scan resolution. The
resulting data file can be saved indefinitely for review and comparison to
future scans. After data is acquired, it is analyzed to identify any areas of
concern, either directly on the instrument or in post-analysis software. Shifts
in data (time/depth) are measured in order to assess the severity of metal
loss. The cursors can then be positioned to define areas for depth or
thickness measurement readings. Weld defects such as porosity, lack of
fusion, and cracking can also be detected when scanning for corrosion and
erosion.