Non destructive testing may be defined as an examination that is performed on an object of any type, size, shape or material to determine the presence or absence of discontinuities, or to evaluate other material characteristics, without changing or altering that object in any way. These tests may also be conducted to determine other characteristics, such as size, structure, dimension, alloy content, grain size, hardness etc. The other names for non destructive testing include Non destructive examination (NDE), Non destructive inspection (NDI), and Nondestructive evaluation (NDE). Although NDT cannot guarantee that failures of the components will not occur, it plays a significant role in minimizing the possibilities of failure of the components.