Non-destructive Testing

Abstract

Defects, such as cracks, porosity and inclusions, which may be potentially damaging may be introduced into materials or components during manufacture, and other defects, such as fatigue cracks, may be generated during service. It is necessary to be able to detect and identify such defects and to ascertain their position and size so that decisions can be taken as to whether specific defects can be tolerated or not. A range of non-destructive test (NDT) methods is available for the inspection of materials and components. Some of the features and applications of the main test methods in use are given in Table 8.1. All these NDT systems co-exist and, depending on the application, may either be used singly or in conjunction with one another. There is some overlap between the various test methods but they are complementary to one another. The fact that, for example, ultrasonic testing can reveal both internal and surface flaws does not necessarily mean that it will be the best method for all inspection applications. Much will depend upon the type of flaw present and the shape and size of the components to be examined.