While there are more than 32 different NDT methods (basic theoretical principal) and even more techniques (the way in which method is applied) only six major methods are primarily used:
Surface and subsurface indications are usually sought by using
- Penetrant Testing (PT)
- Magnetic Testing (MT),
- Visual Testing (VT) or
- Eddy Current Testing (ECT)
Volumetric indications, meaning discontinuities inside materials, can be found using
- Radiographic Testing (RT) or
- Ultrasonic Testing (UT)
NDT operators are technical individuals tasked with the goal of finding, characterising and verifying the presence of discontinuities, monitoring their degradation and report indications that exceed the relevant industrial codes’ acceptance criteria resulting in threats to operational integrity or productivity of a component structure or industrial plant.
Applications of NDT techniques (such as ultrasonic, radiographic, liquid penetrant, magnetic particle, and eddy current testing) depend heavily on personnel training, experience and integrity. Personnel involved in application of industrial NDT methods and interpretation and evaluation of results must be certified by law or by the applied codes and standards governing the specific industry.