Alternating Current Field Measurement (ACFM) is an electromagnetic technique for detection and sizing of surface breaking discontinuities.

It can be used on conductive materials coated with conductive or non-conductive coatings with the surface temperature up to 400 degree Celsius.

The ACFM probe induces a uniform alternating current in the area under test and detects the resulting current flow near to the surface.

This current flow will be distorted around the discontinuity and flow around the ends and faces of the discontinuity. 

The ACFM instrument measures these disturbances in the field and uses mathematical modelling to estimate discontinuity size (length and depth).

Scanning data can  be captured and stored on electronic storage devices.

This non-destructive test technique is very useful for the sub-sea and offshore industry because there is no need to remove the thick protective coating.

This test method can be applied on any in-service structures and pressure equipments, pressure vessels and pressure piping.

This test method is not recommended for short sections or small items.

Weld repairs and localised grinding can cause spurious indications. The minimum discontinuity length that can be detected is 5mm and the accuracy can reduce when multiple discontinuities are clustered.

Compared to other surface flaw detection methods,  Alternating Current Field Measurement (ACFM) test requires highly trained, skilled and experienced technicians.

LMATS professionals are trained and experienced in Alternating Current Field Measurement (ACFM) and holds proven procedures in accordance with ASME V, Article 15