In addition to conventional non-destructive techniques (visual inspections, endoscopy, dye penetrant examinations, magnetic examinations, X-rays, ultrasonic examinations, etc.), there are also other non-destructive techniques in which certain properties of metals and welds can be analyzed on site. When there are doubts about the condition, intact or not, of an installation, its operation, the choice of materials used for its construction, or when damage is found, it is desirable to be able to inspect the installation without taking it out of service.

The use of a portable PMI unit enables an on-site analysis to be done using X-ray fluorescence. The atoms of the work piece are excited with a built-in X-ray tube (40 kV). In an excited atom on the surface of the part, the electrons will be rearranged. This rearrangement is coupled with the emission of energy in the form of photons. These are characteristic of the excited atom. The detector distinguishes between these photons and classifies the atoms there.

Nevertheless, it is not possible to measure all elements with this analytical method, carbon in particular.