The Subspection Cathodic Protection survey system gives a continuous measurement of the cathodic protection potential of the pipeline or structure element. Results are produced as the survey proceeds, so that areas, which have poor protection, can be detected and surveyed in greater detail.
Even buried pipelines can be surveyed, because the system can make corrections for voltage drops in the seabed mud. Anode potentials and output currents are also measured. The computer-controlled data storage can accept navigation and pipe burial data from the submersible operator, so that the cathodic protection information can be plotted in relation to position along the pipe; this enables comparisons to be easily made between successive surveys.
The system can be mounted on a manned or a remotely operated submersible vehicle, provided by a diving company.
The layout is shown in Figure 1 for a remotely controlled vehicle, and consists of the following items.