EVALUATION OF A COMMERCIAL EMATS DEVICE FOR BOILER TUBE WALL THICKNESS MEASUREMENT.

A commercial electromagnetic acoustic transducer (EMAT) material thickness tester was evaluated in the laboratory on a variety of plate materials, and on clean and scaled boiler tubing. In general, signal amplitudes were very weak and variable, though time of flight signals were sharp and reliable. Extensive mode conversions occurred on thin-walled tubing, making the signals uninterpretable. The weak signals and mode conversions made the device unsuitable for measurement of wall thickness on oxide-scaled boiler tubing.