Modern day cathodic protection (CP) design codes are typically highly conservative when compared with early CP system designs. Review of historical surveyd ata from platforms in service for approximately 25 to 30 years illustrates the conservatism now employedw hen constructing new structuresf or installation in the North Sea. This paper illustrates this
level of conservatism by reviewing the CP system performance of a gas gathering platform complex in the Southern North Sea and comparing the results of that review with present day design codes.The paper details the findings of a CP design review and ROV validation impection to determinethe present system status. The effect of combined impressed current and sacrificial anode systems is also illustrated. Finally a discussion on the definitionand optimisation of additional CP system requirements and future survey strategy to ensure protection is maintained to the anticipated end of field life is provided highlighting the cost benefitsof basing retrofit designs on system performance rather than design theory.
Kevwords:cathodic protection, current density, anodes, retrofit
optimisation