Home>ASTM Standards>ASTM E1629-12(R2020) pdf free download

ASTM E1629-12(R2020) pdf free download

ASTM E1629-12(R2020) pdf free download.Standard Practice for Determining the Impedance of Absolute Eddy-Current Probes
1. Scope
1.1 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. 1.2 Limitations—This practice does not address the charac- terization or measurement of the impedance of differential, a-c coupled, or transmit/receive types ofprobes. 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. 1.3 Units—The values stated in SI units are to be regarded as the standard. The values given in parentheses are mathemati- cal conversions to inch-pound units that are provided for information only and are not considered standard. 1.4 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 appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.5 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
5. General Practice
5.1 Use of Eddy-Current Reference Standards—The eddy- current reference standards described in this practice shall not be used for purposes other than measuring the impedance of eddy-current probes as specified in this practice. They shall not be used for standardizing an examination or for determining sensitivity to flaws. 5.2 Responsibility—Initial determination of the impedance values of eddy-current probes shall be performed by the probe manufacturer in accordance with this practice. The results shall be delivered with the probe and maintained by the organization using the probe. The results should include a description of the measurement configuration and impedance values as listed in X1.4. While the retesting of probes may be performed using this practice, only the results obtained before the probe is in use should be compared to the initial impedance values. The impedance results should not be compared to the initial values after a probe has been used.
6. Specific Practice
6.1 Method—Impedance measurements shall be made on an aluminum alloy reference block with a machined slot that conforms to the requirements of this practice. The operating frequency (as specified by the probe manufacturer) may vary for each probe examined, depending on the specific probe geometry, required skin depth, matching impedance, desired signal strength, and application. A commercial impedance measuring instrument that conforms to 6.1.1 shall be used to make the measurements. The measurements will be recorded on the worksheet (Appendix X1) to calculate the probe impedance. The calculated values shall be compared to the acceptable criteria (6.3) to determine probe acceptability. 6.1.1 Equipment—The instrument shall be either a commer- cial impedance measuring instrument or an LCR meter with an oscillator capable of driving a current in the probe at the probe’s operating frequency. The output shall display the probe impedance in either polar coordinates, providing a magnitude and a phase angle, or rectangular coordinates, providing resistive and reactive components of the impedance, or both formats, that is, in polar and rectangular coordinates. This instrument shall be certified as having been calibrated in accordance with the manufacturer’s specifications, with the calibration sticker indicating the calibration date and the required interval or next calibration date.

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