Ultrasonic thickness testing has been used widely to determine rate of corrosion and erosion, or detecting discontinuities below the surface of a variety of materials. Based on the same principal as sonar, a sound beam is transmitted into a material to determine thickness or soundness, and reflects back to the unit.
Ultrasonic volumetric (shear wave) inspection works on the same basic principles as ultrasonic thickness, however angles are introduces. This allows the sound pulse to travel from a smooth base metal into a weld in a controlled manner. The most commonly occurring defects in welded joints are porosity, slag inclusions, lack of side-wall fusion, and lack of root penetration, undercutting and longitudinal; or transverse cracks.
Liquid Dye Penetrant is mainly used to detect fatigue and stress cracks in ferrous or non-ferrous materials. Penetrant testing will also reveal any cracks, pinholes, laps, seams, leaks as well as grinding cracks. This works on the capillary effect that small voids will draw in the dye. After the dye has been administered, the surface is cleaned. Then a developing agent is applied to expose the residual dye, and the void is revealed.
Because magnetization of certain metals is possible, small particles that are attracted to magnetic fields are applied to the surface of the test object after or during induction of a magnetic field, thereby detecting certain discontinuities which are present in the material. Since magnetic particle testing is capable of revealing discontinuities (variations in material composition) economically, it is one of the most used nondestructive test methods.
Visual testing is the only nondestructive testing technique that can be performed without the aid of other equipment. Because the physical means of visual testing is available to almost everyone and because the process seems so intuitive, some people may assume that the technique itself is not very complex. However it takes a trained eye and experience to conduct a successful visual inspection.
The equipment utilized for Flux Leakage Inspection uses very powerful rare earth magnets in order to near saturate the plate in the area of the scanning head. Coil sensors placed between the poles of the magnetic bridge detect the flux leakage fields and provide a low voltage output signal to the electronic module for processing and real time display. The electronic processing and display module is common to both of the MFE Scanning Systems.