Sleipner A was installed in 1992/93. The seawater piping was made in 6Mo stainless steel with some
25Cr duplex valves. The piping system contained chlorinated seawater. After approx. 18 months in
service several leaks were observed in the firewater system due to crevice corrosion in valve
components, flange sealing areas and threaded components.
To avoid more leaks it was decided to install internal cathodic protection in both the firewater and
seawater systems. In 1996 Resistor controlled Cathodic Protection - RCP was installed using
available flanges and fitting access points. This was one of the pilots in the early phase of the
Resistor controlled Cathodic Protection system designs. The design gave a range of anode lifetimes
from 5 to 30 years. The paper will review 10 years of operational experiences from the Sleipner A &
T platforms, from solving some initial problems with the CP system, through historical monitoring
data with comparisons between monitoring data and design values and change out of anodes after
ended lifetime.