Deepwater Retrofits Cathodic Protection on Five Structures in 14 Days
28 April 2008
In February, Deepwater Corrosion Services performed anode retrofits on two subsea development systems in 73 hours. These deep water installations, located in water depths ranging from 775ft to 1,750ft, consisted of:
- Four flowlines, ranging in length from three to nine miles each
- Four well trees
- Two flowline manifolds
- Two umbilical termination units
The CP system consisted of 19 RetroPods paired with standard and customized RetroClamps.
The installation was accomplished utilizing a DP-equipped ROV support vessel equipped with two ROVs. An ROV essentially watches the RetroPod craned down to the seabed, adjacent to the asset, and sets the RetroClamp onto the target member or pipeline. Electrical continuity and CP measurements were monitored using Deepwater’s Polatrak Deep-C Meter and ROV II Probe.
The CP design was optimized in a manner that minimized the number of installation sites, but allowed for maximum flexibility with anode array placement. This design feature enabled the installation team to quickly alter the game plan when they encountered a major escarpment at one lay-down site.
The innovative RetroClamp system allows the anode array to be clamped and electrically connected to a member of any shape or size, completing the circuit necessary for the cathodic protection system to begin polarizing the structure or pipeline. The RetroClamp can be installed by diver or ROV (ROVs in this case).
