There are different models available, one ROV-installable for existing pipes and structures, and one pre-installable solution that can be installed topside before the structure is submerged. Both models operate in the same way and will give the same results when it comes to reliability and repeatability.

Read Audun O. Pedersen’s (ClampOn) article in Oilfield Technology, January 2017:
– Combatting Corrosion »

Transducers are clamped to the outside of the pipe using active ultrasound and exploiting the properties of Acoustic Guided Lamb Waves to detect the changes in wall thickness relative to reference values obtained during the installation of the system. The monitor is designed for permanent installation and will not need any calibration after installation. A variety of configurations are possible. It can act as a standalone monitor running on batteries that have a lifetime of 10 years and sending the data acoustically to the surface, or it can be integrated into the control system via existing cables.

Many governments and petroleum regulations require permanent monitoring of a pipe’s condition, and this instrument provides a constant stream of information about the pipe’s condition at critical points. By installing the CEM the operator can constantly monitor any changes in wall thickness, and will know when if necessary to replace sections of pipe or if there is a risk of leakage.