Location

Williamsburg, VA

Start Date

1-1-1986 12:00 AM

Description

In a standard eddy current method [1] for the inspection of tubing, a probe, consisting of two coils, is translated along the inside of the tube. Measured differences in impedance between the two coils are used to detect flaws in the wall of the tube. Physically what happens is alternating currents in the coils generate eddy currents in the wall of the tube. The magnetic field (primarily the axial component) from the eddy currents reduces the inductance of the coils from the free space values. A flaw will alter the eddy currents, resulting in a local change in magnetic field within the tube and hence a difference in impedance between the two coils.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

5A

Chapter

Chapter 1: Conventional Methodologies

Section

Eddy Currents

Pages

241-248

DOI

10.1007/978-1-4615-7763-8_26

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Measurement of the Induced Magnetic Field in a Flawed Tube

Williamsburg, VA

In a standard eddy current method [1] for the inspection of tubing, a probe, consisting of two coils, is translated along the inside of the tube. Measured differences in impedance between the two coils are used to detect flaws in the wall of the tube. Physically what happens is alternating currents in the coils generate eddy currents in the wall of the tube. The magnetic field (primarily the axial component) from the eddy currents reduces the inductance of the coils from the free space values. A flaw will alter the eddy currents, resulting in a local change in magnetic field within the tube and hence a difference in impedance between the two coils.