ACFM Testing

Alternating Current Field Measurement testing (ACFM) is a form of Non-destructive Testing (NDT) that uses electromagnetism to inspect, detect and size surface break discontinuities (or cracks). It was created from the Eddy Current testing method, and works on all metals. It can also be used on conductive materials coated with conductive or non-conductive coating to high heats – up to 400 degree Celsius.

The ACFM testing method uses a probe to induce an alternative current in the material area being tested, and detects the resulting current flow near the surface. If this current is not disturbed, then the material area is defect-free. If, on the other hand, the current is disturbed or distorted, then this is a clear sign that breaking discontinuities, such as a break or crack, are present. From this point the ACFM device can also calculate the size and depth of this discontinuity.

Because ACFM testing methods do not require device or equipment shutdown, it can be used above and below water. This means ACFM testing can be used to examine the weld joints on any type of structure, on land and sea, from tanks and cranes, to offshore drilling and theme parks.