What is nondestructive testing (NDT)?

The utilization of a variety of testing methods employing techniques and procedures to evaluate and determine the condition or integrity of materials such as metals, composites, plastics, etc. without damaging them.

NDT Methods:

Radiographic Testing (RT): 

short wave-length electromagnetic ionizing radiation energy used to penetrate materials and provide an image for evaluation. Variations in the image are caused by changes in the structure due to attenuation or absorption. RT can be performed using either a gamma or X-ray source.

Ultrasonic Testing (UT): 

high frequency sound energy used to determine the structural integrity of a material. The use of various modes of sound can provide vital information related to a material. Transmitted or reflected ultrasonic energy is displayed on a test unit and evaluated.

Eddy Current Testing (ET):  

an electro-magnetic testing method in which eddy-currents are induced into an electrically conductive test object. Changes in the eddy current flow are detected by the coil or coils and displayed on the test instrument. A variety of test conditions may be determined.

Magnetic Particle Testing (MT):  

the use of magnetic lines of flux to determine discontinuities in the surface (or near surface) of a test object. Fine magnetic particles are attracted to leakage fields and indications are formed that can be seen visually. This method is limited to ferro-magnetic materials.

Penetrant Testing (PT):  

penetrating liquids with good wetting characteristics which incorporate dyes are used to enter surface opened capillaries and provide and image of discontinuities that can be seen visually.  

Visual Testing (VT):  

the use of the human eye to detect discontinuities open to the surface. VT can be either direct or indirect using viewing aids such as video-scopes, mirrors, etc.