VISUAL TESTING (VT)
Visual testing also known as visual inspection is one of the oldest and most common NDT technique which involves the operator looking at the test piece. VT inspections may be by Direct Viewing, using line-of sight vision, or may be enhanced with the use of optical instruments such as magnifying glasses, mirrors, borescopes, charge-coupled devices (CCDs) and computer-assisted viewing systems (Remote Viewing). Corrosion, misalignment of parts, physical damage and cracks are just some of the discontinuities that may be detected by visual examinations.
- Minimal training is required
- Relatively simple and quick method of inspection
- Low cost
- Can be used on a variety of materials
- Advance optical aids enable images to be retrieved and permit access to relatively complex geometries.
- Surface under examination must be accessible to either naked eye or an optical aided tool.\
- Surface must be clean
- Fatigue of the inspector
- Optical aids relatively costly
- Lacks sensitivity of other surface NDT methods
- Reliability depends upon the ability and experience of the inspector.