Visual inspection is the oldest technique among the Non Destructive Tests, and also the most used for its versatility and low cost. In it, the human eye is used as the main instrument, which is often supplemented with instruments for magnification, illumination and measurement. This technique is, and has always been, a complement to all the other non destructive testing, because usually the final evaluation is made by visual inspection.
It does not require a great training to perform a correct visual inspection, but the results will depend largely on the experience of the inspector, and the knowledge it has regarding the operation, materials and other influential aspects of the failure mechanisms that the object can present. Although it is not a general rule, some standards, such as ASME and AWS, require a qualification and certification of the personnel performing the Visual Inspection test, where the hours of experience of the individual to be certified and the visual acuity are taken into account ( corrected or natural) that it can certify. Within the personnel certification standards that involve this test are ISO-9712 and ANSI / ASNT CP-189.