The purpose of the alternating current field measurement method is to evaluate welds in the area of the toe for surface breaking discontinuities such as fatigue cracks. The examination results may then be used by qualified organizations to assess weld service life or other engineering characteristics (beyond the scope of this practice).

Comparison with Conventional Eddy Current Examination—conventional eddy current coils are typically configured to sense the field from the weld in the immediate vicinity of the emitting element, whereas alternating current field measurement probes are typically designed to sense the magnetic field from the weld distant from the exciter.

1.1 This practice describes procedures to be followed during alternating current field measurement examination of welds for baseline and service-induced surface breaking discontinuities.

1.2 This practice is intended for use on welds in any metallic material.

1.3 This practice does not establish weld acceptance criteria.

1.4 The values stated in either inch-pound units or SI units are to be regarded separately as standard. The values stated in each system might not be exact equivalents; therefore, each system shall be used independently of the other.

1.5 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 and health practices and determine the applicability of regulatory limitations prior to use.