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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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There are other advantages<br />

1. Double crystal probes can be focused<br />

2. Can measure thin plate<br />

3. Can detect near surface flaws<br />

4. Has good near surface resolution<br />

Disadvantages<br />

1. Good contact is difficult with curved surfaces<br />

2. Difficult to size small defects accurately as the width of a double crystal<br />

3. probe is usually greater than that of a single crystal probe<br />

4. The amplitude of a signal decreases the further a reflector is situated<br />

5. from the focal distance - a response curve can be made out.<br />

There<strong>for</strong>e single and twin crystal probes are complementary.

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