Visual inspection is one of the most common and most powerful means of non-destructive testing. Visual testing requires adequate illumination of the test surface and proper eye-sight of the tester. To be most effective visual inspection does however, merit special attention because it requires training (knowledge of product and process, anticipated service conditions, acceptance criteria, record keeping, for example) and it has its own range of equipment and instrumentation. It is also a fact that all defects found by other NDT methods ultimately must be substantiated by visual inspection.

While visual inspection is limited to materials surface-only examination, it often detects the most damaging defects. Visual inspection (abbreviated "VT' )by the American Society for Non-destructive Testing (ASNT) of welded components requires inspectors to have a broad knowledge of many technologies, including welding, destructive testing, non-destructive testing and metallurgy, as well as the correct terminology for each.

Advantages

• Inspection performed rapidly and at low cost.
• Ability to inspect complex sizes and shapes of any material.
• Minimum part preparation required.