The original cathodic protection system on the hull comprised approximately 300 sacrificial aluminum anodes. The spar required a life extension significantly in excess of the original 15-year service life, including the CP system.
Both ICCP concepts were modeled to predict the potential distribution and reveal any areas that may be at risk of under- or over-protection. The models raised a few points of attention including:
- Possible interference with the subsea flowlines and umbilicals
- Possible interference with mooring lines
- Possible under-protection of the keel (with the mid-water concept only)
These risks were minimized by optimizing anode placement. That is, each ICCP float or sled was iteratively relocated and remodeled until the risk of interference or inadequate protection was reduced to acceptable levels. This was easily achievable as the CP models were known to be conservative.
Extracts presented from the paper “Cathodic Protection Retrofit of a Spar Platform” David K. Flanery Deepwater Corrosion Services, Inc. Presented at NACE Corrosion 2011, Houston