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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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Instrument Control: REJECT Control<br />

It is intended <strong>for</strong> preventing the display of undesired low amplitude signals,<br />

called grass or hash, caused by metal noise such as echoes from material<br />

grain boundaries or inherent fine porosity. There are two types of REJECT<br />

controls installed on <strong>UT</strong> instruments: nonlinear REJECT and the more<br />

recently linear REJECT controls. Linear REJECT controls offer the advantage<br />

in that they do not affect vertical linearity of the display.

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