Cathodic protection monitoring
SunStation™ light-powered subsea readout

The SunStation never requires batteries, so it can operate in deep water for up to 25 years.

The Polatrak SunStation is a light-powered LED readout system that uses solar panels for power instead of batteries. It can operate in depths of up to 3,000 meters to display numerical data when activated by a powerful light source. Deepwater uses the system in conjunction with its line of CP-monitoring instruments to create a unique subsea solution that can be fitted to structures, pipelines and underwater equipment. When installed in critical areas, the SunStation system can greatly reduce inspection costs by redefining the requirements of the ROV class-and-equipment scope required to conduct a full cathodic protection survey.

 

The most common instruments used with the SunStation are reference electrodes and current-density monitors that allow asset owners to track the performance of cathodic-protection anodes. These electrodes are permanently mounted on the asset and wired to the readouts, which can be placed in ROV-friendly areas. Any class of ROV with a camera and light can record CP potentials, and no additional survey equipment or ROV probes are required. Also, since SunStation requires only visual inspection, a specially-qualified inspector is no longer necessary offshore.

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Applications

The SunStation is a breakthrough for providing a long-term power source for instrumentation in deep water. With battery lifetimes still quite limited, SunStation is the only way to permanently mount an instrument that isn't hard-wired to the surface. So far, SunStation's main applications have been for measuring cathodic protection on structures, pipelines and anodes (when attaching to either of the former is too difficult). Here are some specific applications for CP monitoring with SunStation (pictured right):

 

Subsea trees and manifolds

Using zinc reference electrodes (called V-String electrodes) at key locations on the manifold, the SunStation CP test panel is mounted at a place convenient for the ROV to interrogate the readouts. A cathodic protection survey can be completed quickly any time an ROV is in the area.

Unburied pipelines and deep water flow-lines

The self-contained SmartClamp monitoring station is comprised of a SunStation fitted to Deepwater’s RetroClamp. It can be installed by diver or ROV on any tubular surface – here, a pipeline.

Anode pod monitoring

The SmartPod anode pod with built-in SunStation monitor is a retrofit cathodic protection system. Measuring the cathodic protection levels at the anode allows just as comprehensive an assessment of the performance as an inspection of the asset itself – here, two subsea trees.

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Buried deep-water pipelines

The SmartStation™ is comprised of Polatrak dual-reference cells (Zn and Ag/AgCl mounted on retrofit clamps) and a pair of SunStation monitors mounted in a low-profile, over-fishable instrument housing, which could also be used as an anode sled (in retrofit applications). This system can be installed and interrogated by ROV.

Potential applications are almost limitless, as the SunStation can be connected to any device with DC output. In the realm of cathodic protection, the SunStation could be used to monitor CP on FPS/FPSO moorings or as an external readout for internal locations such as the annular spaces of turrets or I-Tubes, soft tanks or center wells.

The instrument is rated to either 300 meters or 3,000 meters and has an ultra-bright LED readout that’s easily visible from any viewing angle. Deepwater is actively seeking partners to develop alternate applications of this technology. If you have an idea for the use of solar panels underwater to power instrumentation of any type, please contact us.

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Key design points

Reliable cathodic protection measurement

The SunStation provides repeatable, accurate data and eliminates the operator error associated with some CP probes. Fixed instruments don't move or suffer the same calibration problems as portable devices. Because each unit has its own reference ground, the SunStation provides real-time verification of electrical continuity or isolation.

Eliminates the hassle of ROV-interfaced probes

The reference electrodes connected to the SunStation readout can be placed in critical locations on the asset where an external probe placement would be impossible. In addition, by requiring only the ROV's video camera for a survey, the system reduces cost and eliminates the wear and tear on ROV systems associated with stabbing CP probes.

Eliminate separate ROV surveys

With a SunStation system in place, the operator leverages an ROV's presence by providing CP status during any intervention. ROV visits are video-documented, so cathodic protection surveys are carried out any time an ROV is in the area.

Easy to retrofit using the RetroClamp

The SunStation can be retrofit to existing structures and fields with a specially-modified RetroClamp. The clamp can be attached by diver or ROV to any flange or tubular member, and where conditions are stable in deep water, there are several other attachment options.

Video

A subsea cathodic-protection inspection of two SC Risers on a SPAR structure in the Gulf of Mexico. The ROV information has been cropped by the letterbox and some shots have been blurred to protect the privacy of the operator.