Ultrasonic testing (UT) is a family of non-destructive techniques based on propagation of ultrasonic waves in the tested material. In most common UT applications, very short ultrasonic pulse-waves with center frequencies ranging from 0.1-15 MHz, and occasionally up to 50 MHz, are transmitted into materials to detect internal flaws or to characterize the material. A common example is ultrasonic thickness measurement, which tests the thickness of a component to monitor corrosion process.

Magnetic particles inspection is a nondestructive technique used for detecting superficial (or located in shallow subsurfaces) defects in ferromagnetic materials. Once a magnetic field has been created, ferromagnetic particles - suspensed in liquid or in air - are used to detect discontinuities.

It is referred to testing of parts, materials or systems through the imaging of the thermal patterns at the object's surface. Compared with other classical nondestructive testing techniques such as ultrasonic or radiographic testing, thermographic inspection is safe, nonintrusive and noncontact, allowing the detection of relatively shallow subsurface defects under large surfaces (typically 30x30 cm2 at once, although inspection of larger surfaces is possible) and in a very fast manner.

The visual testing is the most common and versatile non-destructive test. It requires adequate lighting, measurement and comparison tools as well as the experience of a qualified technician, to determine the conformity of a component to specifications, drawings. From a theoretical point of view, most of the methods (UT, PT, MT, RX) are visual inspections enhanced / adapted with technological instruments.