Magnetic Particle Testing, also known as MT, involves magnetizing an area to be examined, and applying ferromagnetic particles (the examination medium) to the surface. Particle patterns form on the surface where the magnetic field is forced out of the part and over discontinuities to cause a leakage field that attracts the particles. Particle patterns are usually characteristic of the type of discontinuity that is detected. Magnetic Particle Testing is applied to detect cracks and other discontinuities on the surface or sub-surface of ferromagnetic materials. The sensitivity is greatest for surface discontinuities and diminishes with increasing depth of discontinuities below the surface. Typical types of discontinuities that can be detected by this method are cracks, laps, seams, cold shuts, and laminations.
Dry particle, White contrast or wet fluorescent methods are available.
Penetrant Testing, also known as PT or Dye Pen, involves a liquid penetrant applied to the surface to be examined and allowed for a set amount of time to enter discontinuities. All excess penetrant is then removed, the part is dried, and a developer is applied. The developer functions both as a blotter to absorb penetrant that has been trapped in discontinuities, and as a contrasting background to enhance the visibility of penetrant indications. The dyes in penetrant are either color contrast (visible under white light) or fluorescent (visible under ultraviolet light). The liquid penetrant examination method is an effective means for detecting discontinuities which are open to the surface of nonporous metals and other materials. Typical discontinuities detectable by this method are cracks, seams, laps, cold shuts, laminations and porosity.
Visible and Fluorescent methods are available.
Ultrasonic testing, also known as UT, comprises a range of techniques that send ultrasonic waves through an object or material. These high frequency sound waves are transmitted into materials to characterize the material or for flaw detecting. Most UT inspection applications use short pulse waves with frequencies ranging from 0.1-15 MHz, although frequencies up to 50 MHz can be used. One common application for this test method is ultrasonic thickness measurement, which is used to ascertain the thickness of an object such as when assessing pipework corrosion. Advanced Ultrasonic inspections such as Shear wave or Phased Array are an advanced NDT method that is used to detect discontinuities i.e. cracks or flaws and thereby determine component quality. Due to the possibility to control parameters such as beam angle and focal distance, this method is very efficient regarding the defect detection and speed of testing.
Radiography, also known as RT, utilizes X or gamma radiation along with film or phosphor imaging plates to capture image / data. Radiographic testing offers a thorough and in-depth analysis for welds, castings, pipe thickness, concrete rebar and conduit location and more with the objective of locating and quantifying defects and degradation in material properties that would lead to the failure of engineering structures.