Impressed current cathodic protection (ICCP)

摘要

An open loop ICCP system for a marine structure 22 comprises a plurality of anodes 30 attached to the structure 22 and a DC power supply 32 connected to the anodes 30 by way of power cables 36 to deliver a voltage thereto. A control unit associated with the power supply 32 is operable to set said voltage to a low fixed level. A monitoring unit 34 powered independently of the power supply 32 is operative to monitor said voltage and disconnect the power supply 32 from the anodes 30 if said voltage exceeds said fixed level by a predetermined margin. With low voltage operation the system cathode potential can be maintained to be no more negative than —850 mV, whereby substantially no hydrogen is generated at the cathode, so avoiding embrittlement and the hazardous build-up of gas. The system allows sacrificial anodes to be replaced by impressed current anodes in substantially enclosed spaces, as between inner and outer hull casings of submarines or within seawater piping systems, thereby reducing lifetime costs.