In the mid-2000s, ClampOn developed its Corrosion-Erosion Monitor (CEM), utilising guided ultrasonic waves (GUW) to monitor wall thickness along a section of pipe. Transducers are permanently installed in two circumferential rings.

Later, the provision of a tomographic wall mapping algorithm operating on the data available from a permanent subsea thickness monitor has been asked for. Knowing the transducer positions and pipe geometry, the mean wall thickness losses measured by multiple partially overlapping acoustic paths are combined to improve the measurement of depth and location of the maximum wall thickness loss. The short calculation times makes it suitable for interactive post-processing of monitoring data, offering results in near real time.

Standard tomographic wall thickness mapping became an option mid-2010s, with the integration of the software package CorrPRINT. Systems with full coverage of a pipe section provide three-dimensional maps of wall thickness loss, with key results like minimum wall thickness and defect positions transmitted to the control system. Many wall thickness monitors are equipped with fewer transducers than what is required for standard tomographic wall thickness mapping. The intention and challenge of the “Tomography Light” system is use these simpler and more cost-effective systems and still be able to achieve tomography mapping of a local area where corrosion or erosion is expected to be most severe.

Preliminary numerical and experimental tests yield good results, even with the constraints of the physical measurement principle between CorrPrint and Tomography Light