Electromagnetic Acoustic Transmission (EMAT)

An Electromagnetic Acoustic Transducer (EMAT) will determine the profile of the interior of a sample without having to damage or deform it in any way. 

EMAT is used for:

  • The evaluation of faults or cracks in a component
  • Determining thickness of components in service
  • Calculating the thickness of metal piping without opening or emptying, such as testing for blockages or corrosion on operating pipelines


PrinciplesA non-contact device that generates an ultrasonic pulse in the part or sample inspected. The waves reflected by the sample induce a varying electric current in the receiver. Any faults or cracks reflect the ultrasonic pulse. This return pulse is interpreted by software to evaluate the internal structure of the sample
Based on the response time, the depth of each crack can be calculated and a profile of the interior of the sample can be created.
How and where is it used?Inspection of metal through coatings, pollutants, oxidation and surface roughness
Inspection of extreme hot or cold temperatures
Deployable via automated inspection apparatus

Detection of cracks, general and isolated wall loss and pitting
Interior crack detection
Thickness measurement without contact
ASTM E1774-96 Standard Guide for Electromagnetic Acoustic Transducer (EMAT)
ASTM E1816-96 Standard Procedures for Ultrasonic Examination using Electromagnetic Acoustic Transducer (EMAT) technology
ASTM 1962-98 Standard Test Methods for Ultrasonic Surface Examination using Electromagnetic Acoustic Transducer (EMAT) technology
Form of report or deliverable?Detailed images
AdvantagesNo couplant required
Dry inspection method
No contact required, allows measurement of in-service piping
Less sensitive to surface conditions
Useful in detecting internal conditions that might otherwise be missed with conventional ultrasonic methods.
Acuren has integrated EMAT with AUT C-Scan to allow rapid change-over for prove up scanning on piping systems permitting production rates up to 1,500 linear feet per day.
LimitationsLimited to metallic or magnetic products
Size constraint due to large size of EMAT transducers
AlternativesRT, UT
Certifications of technicians performing the work?
Rope access applicable?