All methods of Nondestructive Examination (NDE) at some point fall back on the most basic of inspection techniques, Visual Inspection. Whether performing a Liquid Penetrant, Magnetic Particle, reviewing radiographs of welds, observing an ultrasonic instrument’s scope, or evaluating eddy current signals, visual examination at some point comes into play in all methods of nondestructive testing. In stark contrast to this very premise, it was not until 1988 that the American Society for Nondestructive Testing (ASNT) recognized Visual Testing (VT) as a formal Nondestructive Testing (NDT) discipline, including qualification and certification parameters within the 2011 Edition of the SNT-TC-1A Recommended Practice document. Since that time VT has now become included in other Codes and Standards that are considered mainstays 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) & National Aerospace Standard (NAS-410).
The term Visual Examination may lead to an over simplification of the method in itself. This is not to say that visual examination methods or techniques are overly complicated, as in most cases they are not. But it is important to also understand that numerous visual examination techniques may incorporate remote viewing equipment, machine vision, fiber optics, video presentation systems, optical prisms, magnetic film and the list goes on and on. Furthermore, it is of possibly even greater importance to understand that timely placed Visual Examinations will detect discontinuities that can only be resolved through other more costly methods once welds have been completed.