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What this test helps us understand
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- vessel surface crack detection and clad thickness measurement
- loss of SS clad over the carbon steel shell
- the thickness of non-electrically conductive coatings on electrically conductive materials
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What we commonly test
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- vessels with carbon steel shell and stainless steel clad
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Test method summary
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- eddy current testing is essentially a near-surface technique
- is based on the principle of measuring changes in the impedance of an electromagnetic coil as it is scanned over a surface of conductive material
- a circular coil carrying an AC current is placed in close proximity to an electrically conductive specimen
- the alternating current in the coil generates an alternating magnetic field, which interacts with the test material and induces eddy currents into the item being tested
- variations in the electrical conductivity or magnetic permeability of the test item, or presence of any flaws, will cause a change in eddy current flow and corresponding change in the phase and amplitude of the measured current
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