Career & Technical EducationNDT Classes

Non-Destructive Testing


Testing Methods


Is the study of the interaction of x and gamma rays with industrial materials.  X-rays and gamma rays are much like light waves, difference being x and gamma rays are extremely short wavelength.  Consequently, they penetrate materials easily.  A film is placed beneath the object and an image is captured on the film.  The radiographer then processes (develops) the film and produces an image of the part and any defects it may contain.  To view radiographs visit Iowa State University.

Ultrasonic Inspection
This testing method is much like radiography except high frequency sound waves are passed through the material.  No image capturing media is used.  When the sound meets a void or a material with a dissimilar acoustic property all or a portion of the sound will be reflected revealing the void or foreign material in the part.  With ultrasound defects can be located and defined within part, or part thickness can be determined. Visit Iowa State University for more information on ultrasonic inspection.

Liquid Penetrant Inspection
Liquid Penetrant is considered one of the more simple inspection methods.  The part is immersed in a Penetrant (much like WD40 with a dye added).  The penetrant pulls the dye into any defects open to the surface.  After removing the excess penetrant, a developer, similar to talcum powder, is applied.  This helps draw the penetrant to the surface of the part and provides a contrasting background for the penetrant.  Penetrant dyes come in either a visible red dye or a fluorescent dye.  Visit to see penetrant materials entering a defect

Eddy Current Inspection
By generating high frequency alternating electrical current through a coil, the associated expanding and collapsing magnetic fields will produce, in a conductive material, a weak electrical current, and its associated magnetic fields.  If the electrical currents are disrupted by a crack, change in material properties, or nonconductive coating, an indication will be produced on a meter or Cathode Ray Tube.  Eddy current inspections are performed on aircraft to locate cracks or to determine paint coating thickness.  Eddy current inspections also are used in electrical generating plants to locate thinning and cracks in tubing. 

Magnetic Particle Inspection
By magnetizing a ferromagnetic material, areas of cracks or other disruptions of the continuity at or near the surface of the material will produce a leakage of the magnetic field.  If fine iron particles are applied to the part, these areas of leakage will attract and hold the iron particles producing an indication on the surface of the part.  Learn more about Magnetic Particle inspection.

Visual Inspection
Visual Inspection is used within any industry before, during, and after an operation has been performed. Visual Inspection is an all-encompassing method that is stressed from materials and processes, all the way to visual inspection of a component using hand tools, video equipment, and material analyzation tools.