Visual Inspection occurs with observation of the external features of a sample without the use of inspection equipment.  

This is the oldest and most widely used non-destructive testing method. The test method is applied to almost every product as a quality assurance tool. The most detrimental unacceptable discontinuities in the objects or items are the surface opening discontinuities. By visually inspecting these items or samples we can successfully detect these unacceptable surface discontinuities without applying expensive test methods. With visual inspection, a technician illuminates the test specimen with light and examines the specimen with the eye. A magnifying glass, mirror, microscope and or borescope may be used to magnify defects which cannot be detected by the unaided eye. This also assists the inspection, quickly carried out and low in cost. The American Society for Nondestructive Testing (ASNT) did not recognize VT inspection until 1988. Since then the VT has now become included in other codes and standards that are considered mainstay of the inspection industry, such as the American Society of Mechanical Engineers (ASME), the American Society for Testing Materials (ASTM), the American Welding Society (AWS) and the National Aerospace Standard (NAS-410).