Alternating current field measurement (ACFM) is an electromagnetic technique for non-destructive testing detection and sizing of surface breaking discontinuities.
[1] The system was originally developed in the early 1990 for the sub-sea and topside inspections of offshore structures without the need to remove the item's protective coating.
Its main purpose is to evaluate welds in the area of the toe for surface breaking discontinuities such as fatigue cracks.
The alternating current field measurement method (ACFM) does not have available performance demonstration initiative results.
Based upon hundreds of performance demonstration initiatives for MT, ET, and alternating current field measurement; probability of detection for ACFM is given below.