Eddy Current Testing

Efficient and cost-effective testing of extensive tube lengths

What is eddy current testing?

Eddy current testing (ECT) is an electromagnetic test method that is widely used for flaw detection and sizing in ferrous and non-ferrous materials. The test unit drives current through a test probe which induces a varying magnetic field around the coil. When the coil is placed in, or on, the test part, a secondary current (eddy current) is induced in the test part. Changes in the test part such as permeability, conductivity, or flaw indica­tions will cause changes in the eddy current field that are used to sort materials or size the depth of flaws.

Corrosion, internal and outer diameter pitting, and mechanical wear are some of the flaws that can be accurately measured by analysis of the flaw signal generated on the test instrument display. Signal phase and magnitude information is used to quantify and characterize the flaw indications through the use of analysis curves created by measuring representative flaws in a calibration plate or tube.

What are the advantages of eddy current testing?

Eddy current test probes can be pulled through the tubes to be inspected at higher speeds than with other test methods. Further, tubing being inspected does not require a high degree of cleanliness. This can save the time and expense required for hydroblasting or chemical tube cleaning incurred when using other inspection methods. Finally, inspection data can be stored and saved to a variety of recording media. This allows data to be archived or retrieved later for review.

Eddy current testing has a wide range of testing applications, and is utilized in the aerospace, petrochemical, power generation, manufac­turing and other industries. Codes and specifications for eddy current testing have been developed by the American Society of Mechanical Engineers (ASME), and ASTM International, as well as the Armed Forces of the United States.

Why use TÜV SÜD America for your eddy current testing requirements?

TÜV SÜD’s inspection professionals are certified to the American Society of Nondestructive Testing (ASNT) Level III and Level II requirements, and have extensive experience in the use of eddy current testing in a range of industrial settings and applications. In addition, we can provide other advanced nondestructive testing and analysis services at customer site locations and in the field to provide maximum flexibility.

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