Non-destructive testing, NDT, is a very broad group of structural or material inspections, and as the name implies, these inspections do not destroy the material/structure being examined. NDT plays a critical role in assuring that structural components and systems perform their function in a reliable and cost-effective fashion. Because NDT does not permanently alter the article being inspected, it is a highly valuable technique that can save both money and time in product evaluation, troubleshooting, and research. NDT technicians and engineers define and implement tests that locate and characterize material conditions and flaws that might otherwise cause serious accidents, such as planes crashing, reactors failing, trains derailing, pipelines bursting, and various troubling events.
This concept is extended and known as Non-Destructive Evaluation (NDE) when combined with assessing the significance of any defects found. However, they are both terms often used interchangeably. Some testing methods must be conducted in a laboratory setting, and others may be adapted for use in the field. Several commonly employed NDT techniques and their characteristics are described below.
Classification of NDT Methods
The variety of techniques available can also be divided into two groups: surface methods, which are used to identify surface and near-surface defects such as cracks and surface porosity, and subsurface methods, which can be used to detect defects that lie under the material’s surface.
- Surface methods
- Subsurface methods