Comparison of Non-Destructive Testing Methods

Non-Destructive Testing Methods

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 TestingVTOldest forms of testingCan check for damage including cracks, corrosion, and misalignment
Liquid Penetrant TestingPTFlexible technique used in the aviation industryCan detect surface defects and structural damage in non-porous materials
Acoustic Emission TestingAEAn abrupt force is usedLeaks and active corrosion can be detected
Leak TestingLTInvolves pressurizing & immersing the test object in a liquiddetects gas (usually air) leaking from the test piece in the form of bubbles.
Radiographic TestingRTcan use both x-rays for thin materials and gamma rays for thicker materialsTo show discontinuities in the testing object
Ultrasonic TestingUTuses high-frequency sound waves to locate defectsconduct examinations and measurements on a test area
Magnetic Particle TestingMTinvolves inducing a magnetic field in the test objectfind discontinuities at or near the surface of ferromagnetic materials
Eddy-current TestingECTinduces an electromagnetic field in a conductive test objectmeasures the secondary magnetic field generated around the electric current 
Vibration Analysis VAused to monitor the vibration signatures generated by a rotating piece of machinery 
Thermal/Infrared TestingIRTmapping the surface temperatures of an objectused to detect damage such as corrosion, delamination, voids, and disbonds
Laser Testing MethodsLMTUseful in detecting tiny flawsuse laser light in different ways to detect deformation on the surface of objects and computer processing to compare stressed and unstressed conditions

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