Alternating Current Field Measurement ACFM
Creates Permanent Record – ACFM provides a permanent record of inspection that can be stored on floppy disks and be replayed, audited, and produced in hard copy.
Approved Equipment and Technique – Approved by ABS, Lloyds, DNV, Bureau Veritas, and OCB Germanisher Lloyd.
Fully Trained and Certified Technicians – All ACFM personnel have been trained, tested and certified by an outside agency that is approved by the Technical Welding Institute and Lloyds Registry.
Alternating Current Field Measurement ACFM was developed during the 1980's from the ACPD (Alternating Current Potential Drop) technique. The development of ACFM combined the ability of ACPD techniques to size material flaws without calibration and, as with eddy current techniques, the additional benefit to work without intimate contact with the inspection surface. This is achieved by maintaining the uniform field (induced rather than injected) and measuring the magnetic fields above the specimen surface instead of the surface voltages.
ACFM was introduced to the oil and gas industry in 1991. The first applications were the inspection of welded joints on offshore platforms and process plants. The technique provides reliable detection and sizing of cracks in metallic components and can be used over paint, coatings and process related residue. ACFM inspection can replace magnetic particle inspection and yields equivalent sensitivity with the added benefit of being able to determine defect depth. The significant advantage over magnetic particle inspection is that surface preparation is eliminated or significantly reduced which saves valuable time and capital resources during critical path outages.