CESCOR performs cathodic protection inspections on subsea pipelines in the open sea, on shore approach, (or landfall) using the following techniques:
- Contact measurements, where feasible
- Potential profile through contactless technique close-to-remote
- Gradient of potential gradient profile
- Trailing wire
Cescor supplies the instrumentation to be applied on the ROVs / AUV or manoeuvrable by divers and qualified personnel employed in charge of the data acquisition on the survey vessels. With the close-to-remote potential technique, the presence of an electric field is exploited between anodes and defects in the pipe coating (see Figure 1), and the potential profile is reconstructed through contact and gradient measurements between two electrodes, one in the pipeline proximity and a second in a remote position. The inspection is carried out with the aid of a ROV or an AUV, on which two probes and the electronics and a support vessel from which the measurements are managed (Figure 2).
The technique of the gradient profile measures the potential difference between two electrodes both near the pipe and allows to locate the possible defects in the coating as well as the peaks in correspondence of the anodes. the designate method of the trailing wires involves a series of applications that have in common the realization of a direct contact to the structure through an electric cable through which potential profiles or measurements are performed opportunely positioning the reference electrode (Figure 3). In the case of pipelines, the profiles can be carried out even with a single contact to the structure, for stretches of many kilometres.
The measurements are carried out with sensors and devices developed by CESCOR (Figure 4), some of which patented. The management of acquisition processes and the following elaboration of data is also submitted to a series of proprietary software developed as well by CESCOR. The interpretation of data makes also use of the FEM Modeling.
