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 provides an improved, low-cost cathodic protection monitoring solution for any subsea application where ROV-assisted surveys are conducted. Cathodic protection monitoring equipment is permanently mounted to the asset, so no probes or monitoring instruments are required on the ROV. Also, since SunStation requires only visual inspection, a specially qualified inspector offshore is no longer necessary. The SunStation provides a real-time readout of CP performance, activated and powered by the lights on the ROV.

Each SunStation is a single-channel device with an independent ground, thus any Polatrak instrument can output to this device. Anode currents, for example, can now be read directly, in real numbers, as can current density. The solar panels that power the system are built into the device, designed to operate for 25 years or more. Light from the ROV instantaneously wakes up the system and a reading is shown.

This system can save an operator significant sums in reduced inspection time every season, and the improved quality and repeatability of fixed monitoring data over conventional probe-based surveys has never before been available.

The readouts should be strategically placed at locations where ROV intervention is required; CP inspection is achieved whenever the ROV visits. The mounting panel around the unit bears inspection point location information and the designation of each channel.

Applications

The SunStation is a breakthrough for providing a long-term power source for instrumentation in deep water. With battery life limits what they are, 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 all been for measuring cathodic protection: on structures, pipelines, and on 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 comprises a SunStation fitted to Deepwater’s RetroClamp. It can be installed by diver or ROV on any tubular – 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 understanding of the performance as an inspection of the asset itself – here, two subsea trees.

Buried Deepwater 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 into 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.

Other potential applications are endless, 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 (soft tanks, center wells, up inside annular spaces of turrets or I-Tubes, etc).

The instrument is rated to either 300m or 3000m, and has an ultra-bright LED readout that is 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 under water, 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. The SunStation provides real-time verification of electrical continuity or isolation, because each unit has its own reference ground.

Eliminates the hassle of ROV-interfaced probes

The reference electrodes connected to the SunStation readout can be placed in truly 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 as a matter of course during any intervention. ROV visits are video-documented, so cathodic protection surveys are carried out de facto any time and ROV is in the area.

Easy to retrofit, using the RetroClamp

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

Video

A subsea cathodic protection inspection of 2 SC Risers on a SPAR structure in the Gulf of Mexico. The ROV data has been cropped by the letter box, and certain shots have been blurred to protect the privacy of the operator.