This practice covers a procedure for determining the impedance of absolute eddy-current probes (bridge-type, air or ferrite core, wire wound, shielded, or unshielded) used for finding material defects in electrically conducting material. This practice is intended to establish a uniform methodology to measure the impedance of eddy-current probes prior to receipt of these probes by the purchaser or the specifier. Limitations—This practice does not address the characterization or measurement of the impedance of differential, a-c coupled, or transmit/receive types of probes. This practice does not address the use of magnetic materials in examination probes. This practice shall not be used as a basis for selection of the best probe for a particular application or as a means by which to calibrate or standardize a probe for a specific examination. This practice does not address differences in the impedance values that can be obtained when the probe and material are in relative motion, as in a rotating probe, since the procedure described here requires the probe and material to be stationary. Units—The values stated in SI units are to be regarded as the standard. The values given in parentheses are mathematical conversions to inch-pound units that are provided for information only and are not considered standard. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

ASTM E1629-12