Alternating Current Field Measurement (ACFM) utilizes various sensors and computer equipment to detect the appearance and size of defects in circumstances when electrical contact is either impossible or not desired.  It is particularly well suited for the inspection of process piping, pressure vessels and aboveground storage tanks.

 

This technology has been used in Europe for years and is gaining popularity in the U.S.  It is used as a quick screening tool to unmask and locate surface breaking flaws that are not shallow stress driven indications.  The inspection has a unique capability to locate start-stop of indications and depth by mathematical presentation. 

 

The procedure when used correctly, can uncover indications under coated surfaces with minimal or no surface preparation.  When an indication is located with the ACFM system, the operator/technician will use conventional mag-particle inspection procedures to define and prove-up the indication.

The ACFM inspection procedure is ideally suited to perform a quick screening of internal pressure vessel welds during turnaround applications with little or no cleaning of the internal surface area of the vessel.  The method has a wide acceptance in the US refining and chemical plant turnarounds. 

 

The ACFM inspection procedure is gaining in popularity for the inspection of larger structural members that are painted, but have to endure a magnetic particle inspection.   The ACFM procedure allows for screening of these joints without removing the coated weld joint.  Typically, paint and coating are removed to bare metal and conventional magnetic particle methods of inspection are applied.

 

This inspection method is ideally suited for in-service inspection of drilling rigs and deep water SPARs and TLPs.

 

To learn more about Alternating Current Field Measurement services, contact one of our ACFM inspectors at 1-800-749-3122 or e-mail us at ACFM@ok-insp.com.