Visual inspection or visual testing (VT) is always performed as the first step in any NDT inspection – unless the specimen is in a location or position that cannot be viewed.
Visual testing requires direct line-of-sight contact with the portion of the specimen to be inspected.
Adequate illumination of the test specimen is also required – as well as a thorough understanding of the nature and origin of potential defects within the test object. The technician must also have detailed knowledge of the specifications controlling the inspection process in order to properly perform visual testing.