asnt ndt courses
Penetrant Testing
(ASNT PT)
With this testing method, the test object is coated with a solution that contains a visible or fluorescent dye. Excess solution is then removed from the surface of the object but is left in surface breaking defects. A developer is then applied to draw the penetrant out of the defects. With fluorescent dyes, ultraviolet light is used to make the bleed out fluoresce brightly, thus allowing imperfections to be readily seen. With visible dyes, a vivid color contrast between the penetrant and developer makes the bleedout easy to see defects.
Magnetic Particle Testing
(ASNT MPT)
This NDT method is accomplished by inducing a magnetic field in a ferromagnetic material and then dusting the surface with iron particles (either dry or suspended in liquid). Surface and near-surface flaws disrupt the flow of the magnetic field within the part and force some of the field to leak out at the surface. Iron particles are attracted and concentrated at the sites of the magnetic flux leakages. This produces a visible indication of defect on the surface of the material.
Radiography Testing
( ASNT RT)
RT involves using penetrating gamma- or X-radiation on materials and products to look for defects or examine internal or hidden features. An X-ray generator or radioactive isotope is used as a source of radiation. Radiation is directed through a part and onto film or other detector. The resulting shadowgraph shows the internal features and soundness of the part. Material thickness and density changes are indicated as lighter or darker areas on the film or detector. The darker areas in the radiograph represent internal voids in the component.
Ultrasonic Testing
( ASNT UT)
In ultrasonic testing, high-frequency sound waves are transmitted into a material to detect imperfections or to locate changes in material properties. The most commonly used ultrasonic testing technique is pulse echo, whereby sound is introduced into a test object and reflections (echoes) from internal imperfections or the part’s geometrical surfaces are returned to a receiver. Below is an example of shear wave weld inspection. Notice the indication extending to the upper limits of the screen. This indication is produced by sound reflected from a defect within the weld.
Visual Testing
( ASNT VT)
The most basic NDT method is visual examination. Visual examiners follow procedures that range from simply looking at a part to see if surface imperfections are visible, to using computer controlled camera systems to automatically recognize and measure features of a component.
