What type of inspection is eddy current?
Eddy current testing is a non-destructive testing (NDT) inspection method used for a variety of purposes, including for flaw detection, material and coating thickness measurements, material identification and establishing the heat treatment condition of certain materials.
How does eddy current crack detection?
If the material contains a crack or flaw which make the spatial distribution of the electrical conductivity nonuniform, the path of the eddy currents is perturbed and the impedance of the coil which generates the AC magnetic field is modified. By measuring the impedance of this coil, a crack can hence be detected.
How often should eddy current testing be done?
approximately every 3 to 5 years
Ideally, testing will occur approximately every 3 to 5 years, possibly more frequently if there is active damage occurring that should be monitored. Including eddy current testing in an annual inspection ensures that testing occurs with the proper regularity.
Is eddy current volumetric?
Several benefits are derived from eddy current testing: It is suited to volumetric flaws such as corrosion, wear, and large porosities, as well as cracking. It can detect surface-breaking, near-surface, and far-surface defects.
Can eddy current detect thickness?
Eddy Current Testing for Thickness Measurement Eddy current testing and more recently eddy current array (ECA) is one of the standards of thickness measurement because it can be used for nonconductive coatings on conductive-base materials. It can determine thickness of non-metallic coatings on magnetic substrates.
How deep can eddy current detect porosity?
0.01 inch
Detection of Porosity Materials porosity also is well within the capabilities of eddy current detection. In fact, because the eddy currents themselves penetrate the materials surface, typically to 0.01 inch or so depending on frequency, subsurface porosity also can be detected.
What materials can be tested with an eddy current tester?
The technology is now widely used in the aerospace, automotive, petrochemical, and power generation industries for the detection of surface or near-surface defects in materials such as aluminum, stainless steel, copper, titanium, brass, Inconel®, and even carbon steel (surface defects only).
Is eddy current ultrasonic testing?
ultrasonic testing (UT), both technologies can deliver quality data. For instance, eddy current testing (ECT) is more conducive to flatter welds and surface flaws than ultrasonic testing. On the other hand, ultrasonic testing is better at detecting flaws on a volumetric level, including thicker welds.
What is eddy current testing?
Eddy Current Testing Eddy current testing is a non-destructive testing (NDT) inspection method used for a variety of purposes, including for flaw detection, material and coating thickness measurements, material identification and establishing the heat treatment condition of certain materials.
What happens when an eddy current probe is energized?
When an eddy current probe is energized at a given alternating frequency while in close proximity to a conductive test specimen eddy currents are induced in the test specimen by means of electromagnetic induction. Detailed Final Reports that discuss component condition, damage mechanisms, and recommendations.
What affects the magnitude of eddy current?
This ‘secondary’ magnetic field opposes the ‘primary’ magnetic field and thus affects the current and voltage flowing in the coil. Any changes in the conductivity of the material being examined, such as near-surface defects or differences in thickness, will affect the magnitude of the eddy current.
How does the depth of an eddy current change with conductivity?
There is a greater flow of eddy current at the surface in high conductivity metals and a decrease in penetration in metals such as copper and aluminium. The depth of penetration may be varied by changing the frequency of the alternation current – the lower the frequency, the greater depth of penetration.