Due to failure of internal coatings in the high pressure and test separators on offshore production facilities, the option to install an internal cathodic protection system was considered. The background to the system selection (covering literature review, discussions with operators, laboratory study and computer modeling) are described.
The initial concept was to install a sacrificial anode system based on high-temperature zinc alloys. However, the prolonged shutdown required to install nearly 3000 kg of anodes in high-pressure separator was not
economically viable (due to deferred production costs). Hence an impressed current system was designed. This required considerable engineering work to overcome objections on electrical safety grounds in the hazardous environment of an oil production facility. Detailed HAZOP studies were carried out and special protection systems
incorporated to ensure safe operation. The final system installed is described together with preliminary data from commissioning program.