Eddy current testing (ECT) is an electromagnetic testing method in which electromagnetic induction is utilised to detect any discontinuities. The basic requirement for eddy current testing therefore is that the material being tested or in the case of paint thickness measurement the substrate, should be electrically conductive. Eddy current testing can be regarded as both a surface as well as subsurface testing method since the depth to which the inspection can effectively be performed depends on the frequency of the excitation current, the electrical conductivity as well as magnetic properties of the material being tested.
If this sounds like a mouthful, then we invite you to dust off your high school knowledge regarding electrical transformers and attend an ECT course.
The techniques utilised in eddy current testing depends on the sample being tested, i.e. whether it is a surface, tube, bar or other more complex shapes since it dictates the type of probe to be used.
Furthermore, the number of frequencies and the inspection mode(s) such as absolute or differential determines the multi- frequency and / or mode technique description.
The presence of magnetic saturation weak magnetic alloys, shielding or focussing nature of the probe as well as the display capabilities extends the technique description. The training course is based on general theory as well as sector specific applications relating, but not limited to, the following standards and specifications:
- ASME Boiler & Pressure Vessel Code – Section V – Subsection A – Article 1 & 8
- ASME Boiler & Pressure Vessel Code – Section V – Subsection B – Article 26
- ISO 15549 ECT – General principles
- ISO 15548 Part 1 ECT – Instrument Characteristics and verification
- ISO 15548 Part 2 ECT – Probe Characteristics and verification
- ISO 15548 Part 3 ECT – System Characteristics and verification
- ISO 17643 ECT – Welds
- ISO 2360 ECT – Non-Conductive coatings – Amplitude sensitive equipment
- ISO 21968 ECT – Non-Conductive coatings – Phase sensitive equipment
- ISO 12718 ECT – Vocabulary