Eddy Current Testing

This NDT method is based on the principles of electromagnetic induction. The flow of electricity, under certain circumstances, can cause magnetism. Magnetism under certain circumstances causes the flow of electricity. When an alternating current (AC) is passed through a coil, a changing magnetic field is generated.  

This method can be applied to tubing, sheets, cylinders and coatings and provides a means for measuring conductivity, detecting discontinuities, and determining the thickness of coating or plating on articles. Since a continuous indication is a part of the basic testing system, automatic production testing is particularly feasible.

The signal indicating the status of the material is obtained almost instantaneously. There is no requirement for allowing time for the indication to develop.  The testing procedures are readily adaptable to go/no go situations. The method is sensitive to many physical and metallurgical variables- thus it has wide application provided the variables, not of interest can be eliminated or suppressed. The only link between test equipment and the item under test is a magnetic field – there is no possible harm to the item. The equipment, for the most part, can be self –powered and there for a portable.

The success of the testing procedure is directly related to the skill of the operator in suppressing variables, not of interest. The procedures are applicable to conductive materials only. The depth of penetration is restricted to a depth of less than one-quarter inch in standard cases. Testing of ferromagnetic metals is sometimes difficult.
 

NDT Consultancy Services provides inspection in ECT for:

    Crack detection
    Conductivity measurement 
    Thickness measurement 

  Applicable Codes for ECT  

    ASME Section V Article 8 – ECT of Tubular Products

    ASME Section V Article 23- Electromagnetic Examination 

Industries where ECT  is used:

*      Nuclear Industries
*      Oil Industries
*      Refinery and Petrochemical Industries
*      Steel Industries
*      Aerospace Industries

Equipment tested with ECT Method:

*      Off - shore platforms
*      Construction and maintenance of pipelines
*      PPressure vessels
*      Above storage Tanks                                       
*      Aerospace vehicles
*      Power generation equipment
*      Research facility