Eddy Current Surface

Horizon Testing Inc. is pleased to offer our clients the option of Eddy Current Surface Inspection for the following applications: gear inspection, boiler composite tube inspection, weld inspection for surface defects, and crack detection on coated vessels or tanks.


Eddy Current Surface Scan using Weld Scan® Probes can detect surface breaking defects, such as cracks, through non-conductive surface coating up to 2 mm in thickness on a weld or the heat affected zone. This ability to detect defects under the coating results in reduced cost and inspection time associated with not having to remove the coating.


Eddy Current inspection can be used to locate cracking on various gear types and sizes. Standing alone, or in combination with Phased Array, Eddy Current inspection provides a more economical and faster alternative to conventional Magnetic Particle inspection.


Eddy Current surface inspection array coils can be used to inspect recovery boiler, non-ferrous composite wall tubes for cracks. Eddy Current provides a fast, economical and reliable means to locate small cracks on these tubes without the extensive preparation required for Liquid Penetrant inspection.


  • Light weight

  • Rugged

  • Versatile

  • Continually scan the wall thickness

  • Dual frequency capability to reduce unwanted signals


The Eddy Current method is based on inducing electrical current (Eddy Current) into electrically conductive materials. Any changes in geometry, permeability, conductivity, or other material anomalies, will disrupt the flow of eddy current and produce a signal on the digital display.

The Eddy Current signal has both amplitude and angular components based on the impedance change that develops across the coil. Variation in the electrical characteristics, anomalies, defects, or geometry changes within the test object will show up in this signal and can be evaluated by a trained technician. These changes make eddy current examination a very useful tool for various applications such as:

  • Coating thickness

  • Material sorting

  • Crack detection

  • Corrosion detection

  • Conductivity measurements

  • Multi-layer inspections


The typical equipment used are the Zetec MIZ21B and the GE Mentor EM Eddy Current instruments. These are the most versatile handheld Eddy Current scan instruments on the market. They offer all the technology and user interface enhancements needed for a variety of applications. They incorporate the power of dual frequency testing capability, digital conductivity testing, as well as non-conductive coating thickness measurement features.