Under SNT-TC-1A, what is the employer's document that spells out its training, experience and examination requirements for each NDT level called?
- Technique sheet
- Quality manual
- Procedure qualification record
- Written practice
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D. Written practice
The written practice is the employer's own document describing how its NDT personnel are trained, examined and certified. A technique sheet describes how to test a specific part, and a procedure qualification record belongs to welding qualification, not personnel certification.
Reference: ASNT SNT-TC-1A, written practice
Passing current end to end through a solid bar clamped between the heads of a wet horizontal unit (a head shot) produces which kind of field?
- Longitudinal
- Radial
- Multidirectional
- Circular
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D. Circular
Current flowing along a conductor sets up a magnetic field in circles around the current path, so a head shot magnetises the bar circularly. A longitudinal field needs a coil or a yoke.
Reference: ASTM E709, circular magnetisation; right-hand rule
In the standard penetrant classification, which removal method is designated Method C?
- Water washable
- Post-emulsifiable, lipophilic
- Solvent removable
- Post-emulsifiable, hydrophilic
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C. Solvent removable
The methods are A water washable, B post-emulsifiable lipophilic, C solvent removable and D post-emulsifiable hydrophilic. Method C is the portable spray-can process most often used for field weld inspection.
Reference: ASTM E1417 and SAE AMS 2644, penetrant classification
What is the approximate half-life of iridium-192?
- 30 days
- 120 days
- 74 days
- 5.3 years
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C. 74 days
Ir-192 has a half-life of about 74 days, so a source loses half its activity roughly every two and a half months and exposure times must be recalculated often. A half-life of 5.3 years belongs to cobalt-60 and about 120 days to selenium-75.
Reference: ASNT Level II RT study topic: isotope characteristics
Which wave mode cannot travel through water or other liquids?
- Shear wave
- Longitudinal wave
- Compression wave
- Any wave above 5 MHz
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A. Shear wave
Shear waves need a medium with shear rigidity, and liquids and gases have essentially none, so only longitudinal waves pass through them. This is why immersion testing sends longitudinal waves through the water and produces shear waves in the part by refraction.
Reference: ASNT Level II UT study topic: wave modes