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Inspection systems with phase-controlled EMAT-antennas for the ultrasonic long range inspection

: Nikiforenko, G.; Bulavinov, A.; Kröning, M.; Jager, W.; Reddy, K.

Indian Institute of Metals -IIM-, Calcutta:
International Conference & Exhibition on Pressure Vessels and Piping 2006 : 07.-09.02.2006, Chennai, Indien
Kalpakam: Indian Institute of Metals, 2006
International Conference & Exhibition on Pressure Vessels and Piping <2006, Chennai, Indien>
Conference Paper
Fraunhofer IZFP ()
electromagnetic-acoustic-transducer; EMAT; ultrasonic testing

The non-destructive testing of pipeline systems under maintenance is an important task. Improving the testing system sensitivity will improve the accuracy of residual lifetime predictions. This leads to the development of new inspection technique.
Typically inspection of welding joints comes under purview of many standards and has become a common practice. When it comes to pipe body, non-availability of standards limits the usage of commonly used testing techniques. Testing of large areas require large amount of time using conventional bulk wave testing. The presence of the anti-corrosion coating makes the testing more complex.
The solution for the above problem is to use guided waves, which improves the speed of testing. The ultrasonic long-range inspection using guided waves made significant progress in the last 10 - 15 years. Generating guided waves at one location can cover very long range. Using this technique, corrosion damage as well as cracks in the pipe section can be detected. In order to obtain a larger range capability low-frequency ultrasonic waves (20 - 250 kHz) are used. The ultrasonic testing over distances up to 100 meters and more is possible.
The testing systems more commonly available in the market for the long-range inspection use piezoelectric probes. Low-frequency electromagnetic US-transducers were developed in Fraunhofer-IZFP, which allow transmitting and receiving of the ultrasonic mode SS0 in thin-walled inspection objects like pipes, plates, tanks and containers. This technique has number of advantages in comparison to systems with piezoelectric excitation.
A multi-channel mobile inspection system for testing of pipe systems using the above transducers was developed in Fraunhofer-IZFP. Technical aspects of probe and electronics design are considered. Field-testing results are presented in the current work.