Non-Destructive Examination Methods Flashcards

What does the term 'sensitivity' mean in the context of liquid penetrant testing?

Answer: The ability of the penetrant to wet and enter tight discontinuities

In liquid penetrant testing, sensitivity refers to the penetrant system's ability to enter and be retained in fine, tight discontinuities, ultimately producing visible or fluorescent indications.

Which phase of the eddy current signal is most useful for characterizing the depth of a defect in a pressure vessel tube wall?

Answer: Phase angle, since deeper defects cause greater phase lag in the eddy current response

Phase angle in eddy current testing is used to characterize defect depth because eddy currents at greater depths experience more phase lag, allowing differentiation of ID and OD defects and depth estimation.

During magnetic particle testing, demagnetization is required after inspection. Which of the following situations most critically requires demagnetization?

Answer: Components that will be welded after MT inspection

Demagnetization is most critical when components will be welded after MT inspection, because residual magnetism can cause arc blow, which deflects the welding arc and leads to poor weld quality.

In UT shear wave (angle beam) examination of a pressure vessel weld, what is the significance of the 'dead zone' near the entry surface?

Answer: The dead zone is where the transducer cannot detect defects due to the main bang pulse width

The dead zone in pulse-echo UT is the region immediately below the examination surface where the initial pulse (main bang) masks detection of near-surface defects, limiting the method's near-surface resolution.

When performing visual inspection of the internal surface of a pressure vessel, which lighting condition is specified by ASME Section V for direct visual examination?

Answer: A minimum of 50 foot-candles (540 lux) at the examination surface

ASME Section V, Article 9 requires a minimum illuminance of 50 foot-candles (540 lux) on the examination surface for direct visual examination to ensure adequate defect visibility.

What is the primary reason for using tandem ultrasonic scanning on thick-wall pressure vessels?

Answer: To detect vertically oriented planar flaws that would not reflect energy back to a single transducer

Tandem UT uses separate transmitter and receiver transducers to detect vertically oriented planar discontinuities (such as lack-of-fusion in heavy welds) that reflect sound away from the transmitting transducer.

In radiographic testing of pressure vessel welds, which type of IQI placement provides the most conservative (strictest) sensitivity demonstration?

Answer: Source-side placement of the IQI on the surface closest to the radiation source

Source-side IQI placement is more conservative because the IQI image must be visible even after radiation passes through the maximum material thickness, demonstrating higher technique sensitivity than film-side placement.