The control is based on the employment of the light like detector of defects.
Analyzing the answer in terms of direction, amplitude, diffusion, it can be found,
on external surfaces, discontinuities like corrosion, oxidation, impacts.
With the aid of optical methods (endoscopes) it is possible the direct observation
of areas placed in inaccessible zones and the consequent location of
a great number of imperfections.
In DUEMME VT method is requested from the customers during maintenance
of chemical and petrochemical plants.