Which NDT method specifically employs visual inspection techniques?

Visual Testing (VT) is a non-destructive testing (NDT) method that fundamentally relies on visual inspection techniques to evaluate the surface condition of materials and components. This method involves the direct observation of structures and materials to detect surface defects such as cracks, corrosion, and other irregularities. VT can be performed with the unaided eye or with the assistance of optical instruments such as magnifying glasses, mirrors, or borescopes to enhance visibility.

In contrast, X-ray Testing (RT) involves the use of ionizing radiation to create images of the internal structure of components, making it primarily an imaging method rather than a visual inspection technique. Magnetic Particle Testing (MT) and Liquid Penetrant Testing (PT) are both methods that utilize different mechanisms—magnetic fields and liquid penetrants, respectively—to reveal surface flaws, but they do not involve visual inspection as the primary means of detection. Instead, these methods require the interpretation of indications created by their respective processes. Therefore, Visual Testing is the distinct method that directly employs visual inspection as its core technique.