Visual Testing (VT), also known as visual inspection, is a most common method of non-destructive testing, yet the important one. Before performing any other NDT methods, it is inevitable to perform an visual inspection to evaluate the parts on what to do next! This method is based on acquiring the information of the tested parts with the aid of visual observation. Visual Testing can be performed with the naked eyes, magnifiers, or using RVI (Remote Visual Inspection) technique.
This technique is the first step of any testing in NDT examination as it is simple, fast, cheap, reliable and could prevent the significant damage at first hand. Visual Testing can be applied to almost all applications including quality control, part integrity inspection, and so on.
Generally, visual testing (VT) can be performed in 2 ways:
1. Direct Visual Inspection
It is when an object is inspected by the naked eyes. Sometimes, the inspectors can use tools for aiding the inspection such as gages, magnifiers, etc. Although, it seems to be easy, it requires an extensive training and experiences to be able to evaluate indications on the parts' surface.
2. Indirect Visual Inspection
It is when an object is inspected or captured through the lens of camera, borescope or other equipment instead of being observed by the eyes directly. The indirect visual inspection is sometimes referred to remote testing inspection (RVI). Indirect visual inspection is usually performed when it is unable to see the parts directly so it is necessary to use some equipment to aid the inspection.
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