Visual inspection is one of the most common and powerful non-destructive testing methods. Visual inspection requires sufficient knowledge of the work piece and the inspector’s sense of vision. For visual inspection to be more effective, training (knowledge of construction and process, prediction of conditions under service, acceptance limit, maintenance, reporting, etc.) and accurate tools and equipment are needed. Also, all the defects found with other NDT methods. They must be proven by visual inspection. Visual inspection is divided into the following three categories:

Direct visual inspection
Remote visual inspection
Optical visual inspection
The most common NDT methods can be called MT and PT, which magnify and make defects visible with simple scientific methods.

Most of the tools required for inspection are simple. Also, optical lens systems such as bore scopes are used to inspect hard-to-reach surfaces.

More complex devices using optical fibers allow the device to be guided into very small channels and holes. In most of these devices, by installing a camera, an image of the inspection can be recorded.