Non-destructive testing belongs to the most important technical methods of surveillance. Similar to medical diagnosis, they can recognize very quickly the hidden defects of components and constructions before and during their operation, so that the occurrence of emergency situations is easily prevented .
    The evaluation of solid objects in order to prevent the risks under operation is rather difficult, their testing being essential during the different phases of manufacturing and during their entire operation as well.
    During the process of shaping a metal object, this can be cooled, contracted, cracked or voided in the structure, and these defects can not be observed with the naked eye. To prevent putting them into operation or causing any kind of damage, the objects with defects must undergo non-destructive examinations.

    The main argument for testing them is the economical efficiency.

    The following aspects are made possible by the use of non-destructive examinations:
    - Preventing loss of production and exploitation. This prevention is achieved by elimination in the early stages of execution of blanks and improper parts;
    - Reducing the operating and maintenance costs;
    - Improving the quality of products;
    - Increasing operational durability and reliability of products;
    - A high degree of reliability;
    - A low degree of risk and avoidance of  losses from possible damage;
    - The possibility of a key prediction for the behavior modes during operation and the optimum operation modes.