EMAT Thickness Gauging and Flaw Detection
One of the areas in which we intend to develop a commercial EMAT system is in non contact ultrasonic flaw inspection and thickness gauging. We have produced a small number of prototypes already of systems suitable for such tasks as inspection of boiler tubes, tank walls and pipes for corrosion and defects. Recently, we have significantly improved performance above other commercially available EMAT systems such that the EMATs can operate effectively without the need for the magnetostrictive effect, and so are not restricted only to oxide covered surfaces. This greatly broadens the scope of application when you consider the advantages of an EMAT:
- No couplant required.
- Can work at small standoffs if required.
- Intrinsically robust as the transducer face can be coated in any non-conductive nonmagnetic material without reducing performance.
- Ultrasound is generated and detected within the conducting region of the surface under test, so tolerant of a wide variety of surface states, e.g. coatings and corrosion.
We have published thickness measurements to an accuracy of better than 1 micron (0.5%) in the lab [1] and 0.5mm (1%) in a realistic “dirty” high temperature industrial environment [2] using our EMAT technique. We also are currently pursuing patents on methods for measuring coating thicknesses at the same time as sheet thicknesses using essentially a more detailed analysis of the same data.
See information on our GS Series EMAT Adaptor Systems
[1] Dixon S, Edwards C, Palmer SB, ULTRASONICS 39 (6): 445-453 OCT 2001
[2] Dixon S, Edwards C, Reed J, Palmer SB, INSIGHT 37 (5): 368-370 MAY 1995
