Eddy Current Testing Procedure as per ISO 17643 and Acceptance Criteriya 
Eddy current testing is a modern NDT method and prime tool in controlling quality of components for Aerospace, automotive, heat exchanger tubes, pipes for oil, gas and structural applications at various stages of manufacturing and in-service inspections for surface and subsurface crack testing. This method can be used to find finest surface and subsurface flaws in any conductive material. Large Spectrum of QA/QC quality control engineering applications are existing applying Eddy current principles. Present Eddy current NDT method has applications in Aerospace Component Inspections, Heat exchanger tube inspections in Oil Gas companies, real time non-contact thickness measurement to control process quality, Material sorting, mixing, Paint and nonconductive coating thickness measurements. Demand for testing is steeply rising due to increasing usage of nonferrous conducting materials for vast number of engineering applications.

Eddy Current Testing, the principles can be used for the following :

  1. Material sorting – Automobile and precision engineering components manufacturers are processing varieties of components. There could be variation design, chemistry, heat treatment or other properties in materials. The most common problem in shop floors is mix up of various grade of materials either chemically different or variation in mechanical properties or metallurgically difference in structures. Various methods of sorting the materials are used but Eddy current testing is the cost effective and less time consuming means of arriving at right conclusion. It is increasing becoming common to sort out the materials, metals components using Eddy current Inspection Technique.
  2. Surface and subsurface flaws/crack detection in conducting materials. Flaws could be cracks, delaminations, and other discontinuities that can be detrimental to the product performance
  3. Conductivity testing for metals to find conductivity and correlate to purity of metals such measuring purity of copper and other conducting materials during manufacturing or in-service inspections.
  4. It is possible to measure coating thickness using Non-contact method by Eddy current testing techniques. The coating can be conductive or non-conductive with few limitations on the accuracy of measurements. Eddy current inspection can be effectively used to find thickness of coatings including paint thickness measurements.
  5. This modern NDT inspection method can also be used for measuring low thicknesses of the order of few millimeters for conductive materials where there is a restriction on using Ultrasonic thickness gauging due to component configuration or the quantum of inspection. Eddy current inspections can be either contact or non-contact type tests. Non- contact methods are suitable for automation and can be used to control process quality for measuring thickness online during manufacturing such as monitoring thickness of Pipes,Tubes, Plates etc.
  6. Eddy current inspection is an effective means of verifying of integrity of engineering structures and estimation of corrosion damages on heat exchanger tubes in Petroleum refineries in Oil and Gas Sector. Routine in-service maintenance inspections using Eddy current techniques yield reliable data for analysis and condition monitoring of Petroleum refineries, power plants, cement plants and structures.
  7. Aerospace : Eddy current inspection detects discontinuities on conducting materials. Magnetic particle testing is impossible to carried out on non-magnetic materials such as Aluminium, Titanium, Magnesium, Copper etc. Eddy current tests are also used to find fine fatigue cracks on aircraft skins, fastener holes and turbine components. High speed rotating scanners fitted to eddy current equipment machines can perform crack detection with greater speed in a minimum of time. Trinity NDT is equipped with modern state of art equipments for testing Aircraft structures that meets international standards, codes, OEM specifications for Electromagnetic Inspections/Eddy Current testing.
Eddy Current Testing:
  1. State of imported Eddy current inspection equipment suitable for onsite inspections.
  2. Multi frequency capability to inspection cracks and corrosion damages in heat exchanger tube inspections.
  3. Our eddy current testing equipments are equipped with Rotating scanner option for inspecting Aircraft bolt holes and Aircraft skins.
  4. Impedance plane display equipments that are designed for general and critical Eddy current inspections. Built in defect recording makes testing and printing reports and finishing the tasks quickly to fulfill inspection requirements.
  5. Experienced ET NDT Level II certified professionals to carryout ET inspections in house and onsite jobs.
  6. In-house ASNT NDT Eddy current testing ET Level III services on Consulting, technique establishments, NDT procedure preparation,
  7. Trinity NDT offers world class training and certification courses to certify for Eddy current ET Level I and ET Level II as per ASNT Recommended practice SNT TC 1A 

We provide reliable inspection services on Eddy current testing fine tuned to the client needs. Our core competence includes experienced team of NDT Level II, III certified professionals on ET, state of art equipments & approved testing procedures that meets national and international standards. We can perform inspection both in-house and onsite at your site or works. We are serving industrial hubs in Bangalore, Chennai, Mumbai, Kochi,  Visakhapatnam-Vizag, Vijayawada, Ranchi, Gurgaon, Noida, Jaipur, Kolkata, Delhi-NCR, Coimbatore, Pune, Nagpur, Patna, Jamshedpur, Ahmedabad, Mangalore, Bhilai-Raipur, Bhubaneswar-Odisha and Hosur Tamilnadu.

Principle of Eddy Current testing

When a test specimen is brought into proximity to the alternating flux field of an eddy current coil, coil flux causes electrons in the specimen to circulate in a swirling eddy-like pattern; hence the term “eddy currents.”Eddy current behavior depends on the properties of both the flux and the specimen itself. So eddy currents are circular alternating currents caused by a varying magnetic field.

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Principle of Eddy Current testing in a Nutshell

When a test specimen is brought into proximity to the alternating flux field of an eddy current coil, coil flux causes electrons in the specimen to circulate in a swirling eddy-like pattern; hence the term ‘eddy currents’. Eddy current behavior depends on the properties of both the flux and the specimen itself. So eddy currents are circular alternating currents caused by a varying magnetic field. If there is a disturbance in eddy current flow paths that will provide an indication for interpretation and evaluation.

Advantages of Eddy Current Testing

  • Sensitive to small cracks and other defects
  • Detects surface and near surface defects
  • Eddy current Inspection gives immediate results
  • ET Equipment is very portable
  • This Method can be used for much more than flaw detection
  • Minimum part preparation is required
  • Eddy current Test probe does not need to contact the part
  • Eddy currents Inspects complex shapes and sizes of conductive materials

Limitations of Eddy Current testing

  • Eddy current inspection is suitable for only conductive materials
  • Surface must be accessible to the Eddy current probe/s
  • Skill and training required to carry out eddy current inspection is more extensive than other techniques
  • Surface finish and roughness may interfere with test results
  • Reference standards needed for setup for every application
  • Depth of penetration is limited
  • Flaws such as de-laminations that lie parallel to the probe coil winding and probe scan direction are undetectable and may get detected only using specially designed Eddy current probes for such applications.


Eddy Current Testing Images

Heat exchanger Coil ECT