Non-destructive testing refers to inspecting the internal structure of mechanical materials without causing damage or affecting the performance of the object being tested, and without harming the internal organization of the object, by utilizing the changes in thermal, acoustic, optical, electrical, and magnetic reactions caused by the existence of abnormalities or defects within the material's structure.

Methods for inspecting and testing the internal and surface structure, condition, and types, quantities, shapes, properties, locations, sizes, distribution, and changes of defects in specimens by means of physical or chemical methods, with the aid of modern technology and equipment.