NDT Non-Destructive Testing
Visual Inspection is the one NDT method used extensively to evaluate the condition or quality of an item. It is easily carried out, inexpensive and usually doesn't require special equipment.
The method requires good vision, good lighting and the knowledge of what to look for. Visual Inspection can be enhanced by various methods ranging from low power magnifying glasses through to boroscopes. These devices can also be used with television camera systems. Surface preparation can range from wiping with a cloth to blast cleaning and treatment with chemicals to show the surface details.
Visual Inspection can sometimes identify where a failure is most likely to occur and identify when a failure has commenced. Visual Inspection is often enhanced by other surface methods of inspection, which can identify flaws that are not easily seen by the eye.