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

Preparatory Notes for ASNT NDT Level III Examination - Ultrasonic Testing

Preparatory Notes for ASNT NDT Level III Examination - Ultrasonic Testing

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PRR- Pulse Repetitive Frequency/Rate and Maximum Testable Thickness<br />

Clock interval = 1/PRR<br />

When Transit time = Clock interval<br />

For pulse echo method:<br />

Maximum testable length = ½ x Velocity x Clock interval<br />

Typically the Clock interval should be 5 time the transit time, i.e. the sound<br />

path should travel 5 times the maximum testable length. (1st BWE, 2nd BWE,<br />

3rd BWE, 4th BWE to 5th BWE.)<br />

Note: The Clock interval has neglected the time occupied by each pulse.

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