NON DISTRUCTIVE TESTING - HEAT TREATMENT - PLANT INSPECTION

AEAcoustic Emission

ACOUSTIC EMISSION

AE inspection is a powerful aid to materials testing and the study of deformation and fracture.

It gives an immediate indication of the response and behaviour of a material under stress, intimately connected with strength, damage, and failure.

Because the AE response of a material depends on its microstructure and deformation mode, materials differ widely in their AE response. Brittleness and heterogeneity are two major factors conducive to high emissivity. Ductile deformation mechanisms, such as microvoid coalescence in soft steel, are associated with low emissivity.

In production testing, AE inspection is used for checking and controlling welds, brazed joints, thermocompression bonding, and forming operations such as shaft straightening and punch press operations. In general, AE inspection can be considered whenever the process stresses the material and produces permanent deformation.

In structural testing, AE inspection is used on pressure vessels, storage tanks, pipelines and piping, aircraft and space vehicles, electric utility plants, bridges, railroad tank cars, bucket trucks, and a range of other equipment items.

Typical uses include the detection of cracks, corrosion, weld defects, and material embrittlement.

Often, in NDT there is no one method that can provide the whole solution; for cost effectviness, technical adequacy, or both, it is best to use a combination of methods.

Because Acoustic Emission has features that distinguish it so sharply from other methods, it is particularly useful when used in combination with them.

Pros

  • The control does not require access to the entire inspection area.
  • For example, for the total coverage of the surface of a sphere with a diameter of about 16 meters, 30 +/- sensors are required.
  • In case of insulation, only small holes in the insulation are necessary for the mounting of the sensor, with a consequent reduction in the cost of the insulation
  • The control takes a few hours, and in some cases, even less.
  • There is no similar technique that can provide 100% volumetric control.
  • The AE test data is digitized and stored on a PC, so that it can be recalled and used at any time, for revaluation and post processing analysis.
  • When using more than one sensor, the AE source can be located and then identify the faulty area
  • Minimization of plant stop for inspection.
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