the magnetic filed is tangential to the pipeline wall surface in the depicted embodiments the planar projection that is tangential to the circumference around the longitudinal axis of the pipeline is equal to zero thus making the magnetic filed u201c b u201d parallel to the longitudinal axis of the pipeline as depicted in fig7 in an area of pipeline wall near the emats of emat belt 3 the direction of the acoustic waves 154 generated by the combined action of the magnetic field and the electrical poles of the transmitting emats is tangential to the pipeline wall surface and within this planar surface the acoustic waves are at an angle to a tangent to the circumference around the longitudinal axis of the pipeline the bi directional helical propagation of the waves is depicted in part in fig7 for the example shown at fig5 7 a magnetostriction effect is used but the arrangement of emats and the method is the same for the case when lorentz forces are used in one embodiment the magnetization system of a magnetic flux leakage mfl inline inspection tool is used to provide magnetic saturation of ferromagnetic pipeline walls the emat belt 3 of fig1 is configured to employ a plurality of emat r t clusters each r t cluster including two receiving emats and one transmitting emat disposed between the two receiving emats the transmitting emat of the r t cluster is adapted to generate ultrasound waves in.