Non-destructive testing (NDT) is a testing and analysis technique used by industry to evaluate the properties of a material, component, structure, or system for characteristic differences or welding defects and discontinuities without causing damage to the original part. NDT is also known as non-destructive examination (NDE), non-destructive inspection (NDI), and Non-destructive evaluation (NDE).
As we know, non-destructive testing can generally be split into two areas: surface techniques and sub-surface techniques. These techniques are then categorized into various testing methods such as visual testing, liquid penetrant testing, acoustic emission testing, leak testing, radiography, ultrasonic testing, magnetic particle testing, eddy-current testing, vibration analysis, thermal/infrared testing, and laser testing.
Let’s have a look at the points which differentiate them from each other.
|Visual Testing||VT||Oldest forms of testing||Can check for damage including cracks, corrosion, and misalignment|
|Liquid Penetrant Testing||PT||Flexible technique used in the aviation industry||Can detect surface defects and structural damage in non-porous materials|
|Acoustic Emission Testing||AE||An abrupt force is used||Leaks and active corrosion can be detected|
|Leak Testing||LT||Involves pressurizing & immersing the test object in a liquid||detects gas (usually air) leaking from the test piece in the form of bubbles.|
|Radiographic Testing||RT||can use both x-rays for thin materials and gamma rays for thicker materials||To show discontinuities in the testing object|
|Ultrasonic Testing||UT||uses high-frequency sound waves to locate defects||conduct examinations and measurements on a test area|
|Magnetic Particle Testing||MT||involves inducing a magnetic field in the test object||find discontinuities at or near the surface of ferromagnetic materials|
|Eddy-current Testing||ECT||induces an electromagnetic field in a conductive test object||measures the secondary magnetic field generated around the electric current|
|Vibration Analysis||VA||used to monitor the vibration signatures generated by a rotating piece of machinery||–|
|Thermal/Infrared Testing||IRT||mapping the surface temperatures of an object||used to detect damage such as corrosion, delamination, voids, and disbonds|
|Laser Testing Methods||LMT||Useful in detecting tiny flaws||use laser light in different ways to detect deformation on the surface of objects and computer processing to compare stressed and unstressed conditions|