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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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A distance amplitude correction curve is constructed from the peak amplitude<br />

responses from reflectors of equal area at different distances in the same<br />

material. A-scan echoes are displayed at their non-electronically<br />

compensated height and the peak amplitude of each signal is marked on the<br />

flaw detector screen or, preferably, on a transparent plastic sheet attached to<br />

the screen. Reference standards which incorporate side drilled holes (SDH),<br />

flat bottom holes (FBH), or notches whereby the reflectors are located at<br />

varying depths are commonly used. It is important to recognize that<br />

regardless of the type of reflector used, the size and shape of the reflector<br />

must be constant. Commercially available reference standards <strong>for</strong><br />

constructing DAC include ASTM Distance/Area Amplitude and ASTM E1158<br />

Distance Amplitude blocks, NAVSHIPS Test block, and ASME Basic<br />

Calibration Blocks.

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