Direct visual examination is the primary technique prescribed by Article 9. This method is performed using the unaided eye, optionally supplemented by natural or artificial lighting, mirrors, and corrective lenses. The examination must be conducted with the inspector's eye placed as close as practically possible to the examination surface, while respecting the 24-inch maximum viewing distance and the 30-degree minimum viewing angle.
Article 9 requires that Visual Examiners meet the following four benchmarks (T-921): asme section v article 9
The remote system must have a resolution capability at least equal to that of direct visual examination. 3. Written Procedure Requirements asme section v article 9