Time controlled gain (TCG) is created to establish reference level on the calibration reflectors so as to apply the acceptance criteria when performing phased array UT. This presentation provides example of using 10% ID/OD notches to set the reference level for ASME B31.3 piping weld inspections. The presentation states that only the reference reflectors as per applicable code should be used for creating a TCG/Reference Level.
TCG process applies gain so that the amplitude from the reference reflector is normalized to 80% full screen height for the range of angles and the sound path. This is applied by the instrument for each of the focal laws. With a resolution of 0.5 degree, a sweep angle range of 40-70 degrees will result in 61 focal laws (40, 40.5, 41, 41.5 ....70). Therefore, a separate gain value is applied to each focal law by the instrument. Once the TCG is applied, the reflected signal amplitude will be 80 +/-5 % from both the 10% ID and the 10% OD notches for all the angles and for the full range of sound path to cover 2T
22 фев 2023
