JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech IV PRACTICAL NON-DESTRUCTIVE TESTING Previous Question Paper (July/August - 2022 - R18)

Visual inspection tools are categorized based on the accessibility of the surface and the level of detail required. The essential tools include:

• Direct Viewing Aids: Magnifying glasses (typically 2x to 10x), flashlights, and high-intensity lamps for proper illumination.
• Optical Instruments: Borescopes (rigid or flexible) and fiberscopes for inspecting internal cavities or restricted areas.
• Measurement Tools: Steel rules, calipers, micrometers, and depth gauges to quantify surface discontinuities like pits or cracks.
• Surface Profile Gauges: Welding gauges (e.g., fillet weld gauges) to check weld geometry and profile.
• Mirrors: Inspection mirrors for viewing hidden corners or the backside of components.
• Digital Imaging: Video borescopes and digital cameras for capturing and documenting inspection results.

Visual inspection in NDT is generally divided into three distinct stages to ensure a systematic and comprehensive evaluation of the component:

1. Pre-inspection Stage: This involves reviewing the component's design drawings, material specifications, and history. The surface must be cleaned of oil, grease, scale, or coatings that could mask defects. Proper lighting conditions are established, and the inspector verifies that all necessary tools are calibrated and available.
2. Inspection Stage: This is the actual execution phase where the inspector systematically examines the surface. It involves both direct and indirect viewing. The inspector looks for surface-breaking discontinuities such as cracks, porosity, corrosion, mechanical damage, or geometric deviations. All findings are noted, and measurements are taken for any observed anomalies.
3. Post-inspection Stage: This stage focuses on documentation and evaluation. The inspector compares the findings against established acceptance criteria or codes (e.g., ASME, AWS). A final report is prepared, documenting the inspection results, the location and size of any defects, and a conclusion regarding the component's serviceability or the need for further non-destructive testing.