ACFM - Electromagnetic
Alternating Current Field Measurement (ACFM) is an electromagnetic inspection technique developed for fast scanning to locate cracks in welds and surface materials covered by paint, coating and marine growth. The technology relies on the fact that an alternating current flowing in a component, will be disturbed by the presence of a crack. It is often used to identify the size of the surface-breaking cracks in metal components. Also, DELTA GROUP utilizes ACFM on a variety of surfaces, including strictly adhered coatings and surfaces containing minor scaling and debris. Its versatility eliminates the need for pre-cleaning prior to inspection, and test indications can be sized to show the depth and length of indications. Besides, DELTA GROUP uses ACFM extensively for offshore platform applications on piping and structural supports, in addition to processing the piping in oil and gas facilities. DELTA GROUP’s clients in the infrastructure and transportation sectors have also benefited from ACFM’s rapid inspection and defect analysis capabilities.
The ACFM probe introduces an electric current locally into the structure and measures the associated electromagnetic fields close to the surface. The presence of a defect disturbs the associated fields, and the information is graphically presented to the system operator. The ends of a defect are easily identified to provide information on the defect’s location and length. The significance of a defect, in terms of structural integrity, generally depends on the depth of the defect. Using mathematical models, the system also provides the depth of the defect, thus allowing an immediate evaluation of the significance of the crack indication.