In contrast to NDT, other tests are destructive in nature and are therefore done on a limited number of samples ("lot sampling"), rather than on the materials, components or assemblies actually being put into service.
These destructive tests are often used to determine the physical properties of materials such as impact resistance, ductility, yield and ultimate tensile strength, fracture toughness and fatigue strength, but discontinuities and differences in material characteristics are more effectively found by NDT.
Today modern nondestructive tests are used in manufacturing, fabrication and in-service inspections to ensure product integrity and reliability, to control manufacturing processes, lower production costs and to maintain a uniform quality level. During construction, NDT is used to ensure the quality of materials and joining processes during the fabrication and erection phases, and in-service NDT inspections are used to ensure that the products in use continue to have the integrity necessary to ensure their usefulness and the safety of the public.
NDT Test Methods
Test method names often refer to the type of penetrating medium or the equipment used to perform that test. With the rise of new NDT techniques through the last decades, a split up can be made between the conventional NDT methods and the newer/advanced techniques.
The most common conventional NDT methods are: Acoustic Emission Testing (AE), Electromagnetic Testing (ET), Leak Testing (LT), Magnetic Flux Leakage (MFL), Liquid Penetrant Testing (PT), Magnetic Particle Testing (MT), Radiographic Testing (RT), Ultrasonic Testing (UT) and Visual Testing (VT).
Amongst the advanced NDT techniques are techniques like: Time of Flight Diffraction (TOFD), Ultrasonic Phased Array (UTPA), Ultrasonic Corrosion Mapping, Eddy Current Array (ECA) and Digital Radiography
The NDT methods/techniques provided by KTN Belgium are a mix of conventional methods including VT, PT, MT, UT, LT and MFL, and the advanced techniques TOFD, UTPA and Corrosion Mapping.