CWI Nondestructive Examination Methods 2 — Questions and Answers
Question 1: When performing liquid penetrant testing, what is the purpose of the dwell time?
- To allow the developer to absorb excess penetrant
- To allow the penetrant to seep into surface-breaking discontinuities (Correct answer)
- To allow the cleaner to remove the penetrant
- To allow the part to reach ambient temperature
Correct answer: To allow the penetrant to seep into surface-breaking discontinuities
Dwell time allows the penetrant to enter surface-breaking discontinuities through capillary action.
Question 2: Which ultrasonic testing technique uses two separate transducers, one for sending and one for receiving?
- Pulse-echo
- Pitch-catch (Correct answer)
- Resonance
- Immersion
Correct answer: Pitch-catch
The pitch-catch (through-transmission) technique uses separate transmitter and receiver transducers.
Question 3: In radiographic testing, what does a higher kilovoltage (kV) setting primarily affect?
- Quantity of X-rays produced
- Penetrating power of the X-rays (Correct answer)
- Film exposure time only
- The size of the focal spot
Correct answer: Penetrating power of the X-rays
Higher kV increases the energy and penetrating power of X-rays, allowing inspection of thicker materials.
Question 4: What type of magnetic particle indication appears as a tight, sharp line and is typically associated with a crack?
- Nonrelevant indication
- Broad fuzzy indication
- Sharp linear indication (Correct answer)
- Rounded indication
Correct answer: Sharp linear indication
Cracks produce sharp, well-defined linear indications because the magnetic flux leakage is concentrated at the tight discontinuity.
Question 5: An eddy current test is being performed on a non-ferromagnetic tube. Which property does NOT significantly affect the eddy current signal?
- Electrical conductivity
- Magnetic permeability (Correct answer)
- Wall thickness
- Surface cracks
Correct answer: Magnetic permeability
Non-ferromagnetic materials have a relative magnetic permeability of 1, so permeability does not affect eddy current signals in these materials.
Question 6: In visual testing (VT), a weld convexity that exceeds the allowable limit is best described as:
- Undercut
- Overlap
- Excessive reinforcement (Correct answer)
- Incomplete fusion
Correct answer: Excessive reinforcement
Excessive reinforcement refers to weld bead height that exceeds the code-specified maximum convexity limit.
Question 7: Which RT artifact appears as a lighter area on the film and may be caused by back-scattered radiation?
- Film fog
- Back scatter (Correct answer)
- Scattered radiation streak
- Double-wall image
Correct answer: Back scatter
Back scatter from structures behind the film cassette causes a lighter (less dense) area on the radiograph, often appearing as a 'B' marker image.
CWI Nondestructive Examination Methods 2
When performing liquid penetrant testing, what is the purpose of the dwell time?