ASME BPVC 2023 Section V

F-480 EVALUATION
F-481 DETECTION
TFM does not necessarily improve resolution or sensitivity,
which is more dependent on the array, wedge definition,
and particular method used. The potential for
better resolution improves when the search units are
properly designed for the examination. Also, the absolute
detection capability of the FMC/TFM method can be improved
when a combination of modes is considered.
The detection of an indication located where the flaw
would otherwise be hidden by geometry is a potential advantage
of this technique. Having an enhanced image
usually leads to a better and more accurate interpretation
of the image and the different indications within.
Table F-471-1 ð23
Ultrasonic Imaging Modes
Illustrated Example of an Imaging Mode [Note 1] Mode [Note 2]
Datum
Direct transmit, direct receive: TT, LL
Datum
Direct transmit, indirect receive or indirect transmit, direct receive: TTT,
TTT, LLL, LLL, LTT, TTL, TTL, LTT
Datum
Indirect transmit, indirect receive: TTTT, LLLL, TLLT
Datum
Direct transmit, direct receive: LL, TT
Datum
Indirect transmit, indirect receive: TTTT, LLLL, TLLT
NOTES:
1 Each sketch is representative of a specific mode.
2 This is not an exhaustive list of modes.
ASME BPVC.V-2023 ARTICLE 4
149