RetroBuoy™
Impressed current cathodic protection system for large structures

The most efficient and environmentally responsible cathodic protection retrofit system available.

RetroBuoy is a high-capacity impressed current cathodic protection system, designed primarily to be retrofitted to existing structures. It utilizes impressed current titanium anode rods, housed in buoyant floats. This design keeps the anodes in constant contact with the seawater, maximizing the efficiency of the cathodic protection delivered. The sled that anchors the buoys is placed a certain distance from the protected structure, in order to distribute the cathodic protection current more evenly over larger areas. Floating platforms, complex steel structures such as fixed jackets, or structures with many pilings in a tight geometry, such as port facilities or loading jetties benefit immensely from using this type of technology.

Maximum Efficiency - To maintain appropriate levels of protection, individual RetroBuoy anode sleds can be rated anywhere from 150 – 500 Amps. The compact size and remote location of the RetroBuoy directly on the seabed simplifies the installation procedure, keeping the installation portion of the retrofit project cost-effective. As installation costs typically dominate a large offshore cathodic protection upgrade, RetroBuoy thus provides the lowest installed cost per Ampere/ Year of any cathodic protection system available.

Transformer Rectifier(s) and Cabling - As with all impressed current CP systems, the RetroBuoy requires a transformer rectifier topside and cabling down to the sea floor. Routing the cable can be done in many different ways, depending on the conditions of each particular project. Several stock scenarios exist, and for situations that require a new solution, our team of N.A.C.E. certified corrosion engineers and CP designers can adapt existing installation procedures. In addition, our partnerships with key transformer / rectifier manufacturers in the US and UK allow us to provide complete systems in compliance with any local electrical requirements and safety codes.

Applications

Large Offshore Platforms

Situated approximately 100 feet (30 m) from the platform jacket, the RetroBuoy can provide up to 400 Amps of cathodic protection, protecting approximately 80,00 sq ft of underwater steel. Typically, the cable is routed to the surface through an "I" or "J" tube, depending on the structure. In some recent installations, a tensioned clamp can be used to thread the cable safely inside the jacket.

Smaller Offshore Platform Complexes

For structures clustered together and electrically connected via a bridge, many times a single 400 Amp RetroBuoy can protect the entire complex. Exact requirements vary, depending on the size and depth of each structure. Several of these retrofits have been performed in the Gulf of Mexico. Please visit our project experience section for specific information.

Loading Docks / Wharves

For all varieties of dock and jetty structures, the RetroBuoy Jr. (single float version of the RetroBuoy) provides reliable cathodic protection when depth and current conditions allow. Typically water depths must be moderate to deep, to avoid the RetroBuoy interfering with vessels.

FPSO’s (Spread Moored)

For protection of spread-moored FPSO's, the RetroBuoy anode sled has proven to be very efficient and effective in providing cathodic protection for the mooring. The sleds sit on the seabed and the feed cables are deployed in a "Lazy S" configuration. Spread moored FPSO’s are particularly suited to this strategy, as the remote anodes can protect a large area of mooring chain and other hardware.

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Key design points

Superior anode efficiency

MMO activated Titanium electrodes allow the anode sled to be operated at very high current output. Installing the electrode elements in buoyant modules ensures that they remain surrounded by clean seawater, optimum conditions for high current output. If the anode were allowed to become silted at all they would have to be significantly de-rated to avoid premature failure.

Compact design

The RetroBuoy's sled base is compact and easily handled by most offshore installation vessels.

Designed for harsh environments

The oil-filled, pressure-compensated electrical junction box, which houses the electrode cables, allows the system to operate efficiently at any depth. Anode cables are wire in parallel to the main feed cables, providing a high measure of redundancy in the event of an unforeseen mechanical impact.

Multiple applications

New innovations in dynamic cable design are allowing more cost effective deployments of these systems on FPSO’s or in deep water. Routing the power cable from the seabed to the surface via ROV eliminates a major installation cost for the system.

Video

RetroBuoy cable being over-boarded. Buoy sleds are atop Deep Down HDU/reels aboard Oceaneering's The Performer.