The present project focuses on two specific technologies, the Long Range Ultrasonic Transmission (LRUT) and (EMAT) and their main objective will be to deploy the respective clamping manipulator and scanning manipulator to a ROV C class.



The LRUT clamping manipulator already developed will be used for long range 12’’ pipe inspections using generation of guided ultrasonic torsional waves. This system was specifically developed for detection of corrosion in jacket support structure legs, cross members & flow lines. When in position the LRUT transducer ring generates an ultrasonic wave that propagates down the pipe for several tens of metres in either direction. Corrosion/erosion or significant weld defects cause the emitted ultrasonic pulse to be reflected back to the transducer ring that then enables the extent and axial/circumferential position of the defect to be determined.

As you can confirm from the previous project, this technique is already deployed for underwater trials and tested using a ROV system, this technique is at TRL6 targeting to reach with this new SubCTestDEMO project a higher TRL.



For short ranges, as bulk waves or as lamb waves, EMATs offer adequate sensitivity with the important benefit of not requiring ultrasound liquid couplant or direct contact with the test surface. Test surfaces can also be quite rough without loss of sensitivity, as long as the EMAT coils are close enough to the surface to induce eddy currents. This normally requires a gap of less than 0.5mm. Another advantage of EMATs over PZT transducers arises where curvature reduces the amount of contact between a flat PZT element and the surface when testing pipes. The EMAT efficiency does not rely on this, since the performance can tolerate a degree of so-called lift-off between coils and surface.

The primary aim of including an EMAT to complement the measurements performed with the LRUT collar is to provide a method of evaluating with precision the indication detected by the LRUT. This means moving the EMAT sensors to the position of the indicator in order to scan with the EMAT.

Prototype PPM type EMATs were investigated in the original SubCTest project, commercial solutions for that are already available and will be used to develop the new scanning proposed in this project.