JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech IV NON DESTRUCTIVE TESTING Previous Question Paper (December-2023/January-2024 - R18)
Note: Part A is compulsory (25 Marks). In Part B, answer any one question from each unit (10 Marks each).
Part A
What are the differences between endoscope and bore scope?
Answer
- Borescope: Primarily designed for inspecting straight or slightly curved internal cavities of machinery, engines, or pipes. They typically utilize a rigid or semi-rigid rod containing a series of lenses or fiber optics to transmit the image. Borescopes are generally used in applications where a direct line of sight is possible or where the path is relatively linear.
- Endoscope: Specifically engineered for navigating complex, highly curved, or tortuous paths. They are characterized by their high degree of flexibility and articulation, often featuring a steerable tip controlled by the operator. While the term is frequently associated with medical diagnostics, industrial endoscopes (or fiberscopes/videoscopes) are essential for inspecting intricate internal geometries where a rigid instrument would fail to reach.
- Key Distinction: The fundamental difference lies in the flexibility and articulation; borescopes are optimized for structural rigidity and clarity in linear access, whereas endoscopes are optimized for maneuverability and navigation through non-linear, multi-bend environments.
What are the limitations of visual methods?
Answer
- Surface Accessibility: Visual inspection is strictly limited to the surface of the component. It cannot detect internal defects such as subsurface cracks, voids, or inclusions unless they manifest as surface-breaking features.
- Human Subjectivity: The effectiveness of the method is highly dependent on the inspector's visual acuity, experience, and concentration. Factors such as fatigue, poor lighting conditions, and psychological bias can lead to inconsistent results and missed indications.
- Limited Documentation: Traditional visual inspection often lacks a permanent, objective record of the findings. While modern digital imaging can mitigate this, standard manual inspection relies heavily on the inspector's subjective report, which may be difficult to verify later.
- Geometry Constraints: Complex geometries, narrow bores, or restricted access areas often prevent direct line-of-sight inspection. While borescopes or mirrors can be used, they introduce additional optical distortions and limitations in resolution.
- Surface Condition Sensitivity: The presence of surface contaminants like paint, heavy oxidation, grease, or dirt can easily mask critical defects, necessitating thorough surface preparation before inspection can be reliably performed.
Define the term capillary in dye penetrant method.
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List the methods for generating magnetic fields.
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What is wavelength? Write the wave length of x-rays and gamma rays?
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Define the term sensitivity in radiography.
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What is shear waves in ultrasonic testing?
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What is attenuation in ultrasonic testing?
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List the types of probe used in eddy current inspection.
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What are the characteristics of eddy current?
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Part B
Explain in detail the leak detection process.
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Explain the principle and detection of cracks by insitu-metallography technique.
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Explain in brief about the following:
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Explain the principle and working of magnetic particle method for detecting subsurface defects.
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Explain the procedure for detecting defects by fluorescent radiographic method.
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What are the functions of screens in Radiography Testing? Compare metal foil screen and fluorescent salt screen.
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What are the different modes of wave propagation in Ultrasonic Testing (UT)?
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With neat sketches explain the procedures of Pulse echo method of UT.
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Explain the different types of method used for generation of magnetic field in eddy current testing.
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Explain the potential drop method of eddy current testing with neat sketch.
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