Abstract
This paper proposes an advanced techniques for exciting and receiving the torsional guided wave to detect flaws in pipe systems. It is known that there are some difficulties in selecting and exciting of modes by using the nickel strip attached on pipe systems, such as qualification of residual magnetic field and excitation of the unwanted modes etc. In order to overcome these difficulties we propose a new sensor, so called Crossed-coils sensor. We prove that it is possible to select the modes to be excited and to find an optimal excitation condition for torsional modes by using the proposed sensor.
