Non-Destructive Testing

Introduction To Ndt Methods

Non-Destructive Testing is the branch of engineering concerned with all methods of detecting and evaluating flaws in materials. Flaws can affect the serviceability of the material or structure so NDT is important in guaranteeing safe operation as well as in quality control and assessing plant life. (British Institute of Non-Destructive Testing, BINDT)

NDT is used during fabrication before the product enters service, for in-service inspection and condition monitoring of operating plant. It can also be used to measure materials physical properties such as hardness or internal stress. The test methods themselves, as the name suggests, have no damaging effects on the material or structure under inspection.

Visual testing is one of the most common methods in NDT as a surface inspection would always be done first to assess the presence of surface discontinuities and evaluate whether further NDT testing and equipment may be needed. Visual testing is less expensive than volumetric NDT methods which look for body defects and need more time, expense and resource.

NDT test methods require the operator to look at the surface of the component being inspected, therefore visual testing is essential in most other NDT test methods.

The next section details an overview of NDT methods.