Way Ahead In Corrosion Control


Impressed current cathodic protection (ICCP) anode 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 as a retrofit for existing structures. It utilizes impressed-current titanium-anode rods housed in buoyant floats. This configuration keeps the anodes in constant contact with seawater, maximizing the efficiency of the cathodic protection.



Very cost efficient

RetroBuoy™ provides the lowest installed cost per ampere/year of any CP system available.

To maintain appropriate levels of protection, individual RetroBuoy™ anode sleds can be rated anywhere from 150 to 500 amps.

The compact size and remote location of the RetroBuoy™ on the seabed simplifies the installation procedure and increases the cost-effectiveness of the retrofit.

These installation costs typically dominate a large offshore cathodic protection upgrade and the RetroBuoy™ eliminates most superfluous work.

South China Sea JUN2010 233-TB_1024x768.jpg

Video: Shell Leman ICCP Retrofit

Key design factors


Superior efficiency

Mixed-metal-oxide-activated titanium electrodes allow the anode sled to be operated at a very high current output. Installing the electrode elements in buoyant modules ensures that they remain surrounded by clean seawater.


Compact protection

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


Customizable cabling

Routing the ICCP system cable can be done in a variety of ways depending on project needs. 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.


Durable design

The oil-filled, pressure-compensated electrical junction box that houses the electrode cables allows the system to operate efficiently at any depth. 

Video: RetroBuoy™ installation

RetroBuoy™ overview


Current output

Each RetroBuoy™ can put out up to 500 amps of cathodic protection current, enough to protect 80,000 sq. ft of steel.


Anode floats

Each anode float contains three mixed-metal oxide anodes.

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Transformer rectifier

Each RetroBuoy™ is powered by a TR on the surface.



Depending on the particular installation, different cable specs are used. All cables are double-armored single conductors. Cable management through the splash zone is a critical aspect of platform retrofits. J-tubes or I-tubes can be used. Dynamic cable can be configured in a lazy S for FPSO installations.


Model name Anodes modules                   Current rating (A)                   Anode to structure*                   Anode to sea floor                   Applications                                    
RetroBuoy Junior 1 150/200 3m(10ft) 0.7m (2.3ft) Docks and harbors, small offshore structures, jacket complexes, in tropical oceanic conditions
Retrobuoy (RB-4) 4 400/500 30m(100ft) 2.1m (7ft) Large offshore structures in harsh oceanic conditions with an unstable sea floor

Retrobuoy Gallery

Project experience

GOM structures

Project case study: Cathodic protection retrofit on five structures in fourteen days

  • 5 fixed jackets
  • Install time: 14 days
  • 210' four point boat

PanYu 30-1

Project case study: ICCP anode retrofit for eight-leg structure in the South China Sea

  • Water depth: 200 m
  • Fixed monitoring

Deepwater installs RetroSleds™ to protect two pipelines

  • 2 RetroSleds™ and 4 RetroClamps™ on 8" pipeline
  • 1 RetroSled™ and 2 RetroClamps™ on 12" pipeline
  • Pipelines at 210' and 220' depth

LAF-1 & 2 Platforms

Project case study: Single float RetroBuoy™ systems installed in the Gulf of Guinea.

  • Installation: ROV
  • Impressed current anodes

Ewing Bank 305-A

Project case study: Two large impressed-current anode sleds installed on a GOM platform

  • Water depth: 300 ft
  • 20 year life extension
  • 800 Amps of CP current

Olympus Field PBGs

Project case study: Self-monitored anode sled protects 24 new PGBs at 3,000 ft for 45 years.

  • Installation: ROV
  • Install time: 30 hours
  • Battery-free monitoring
  • 45-year design life

Four RetroSleds™ installed on two pipelines

One installed on 10" line, three on a 6" line

  • Installed from jack-up boat
  • Divers helped place the sleds
  • In Gulf of Mexico, south of Louisiana

Four platforms retrofit near Trinidad

59 anode sleds, 3 clamp-on anodes used

  • 59 anode sleds were required
  • 3 Dual-anode clamp-ons were used
  • Smaller booster anodes added to top of sleds
  • Systems were connected via RetroClamps™

Anode sled installed on fixed-jacket platform

Sled replaced anodes removed during construction

  • Anode sled was attached via RetroClamp™
  • Saturation divers used to place sled

RetroSled™ installed on subsea pipeline

6" pipeline in the Gulf of Mexico

  • Pipeline near Renaissance MP 76 platform
  • RetroSled™ used to provide CP
  • RetroClamp™ provides electrical connection
  • Located in the Gulf of Mexico

RetroPods™ installed on FPU subsea equipment

Wellheads and gravity bases protected by RetroPods™

  • 12 RetroPods™ and 18 Web-RetroClamps™ installed
  • 10-year life extension
  • 115 meter water depth

RetroPods™ installed on wellheads and SUTA

Three anode sleds protect subsea equipment

  • RetroPod™ anode sleds installed
  • RetroClamps™ provide electrical connection

Arnold / Oyster fields

Project case study: Anode retrofit on two deep-water subsea fields in the Gulf of Mexico

  • Installation: ROV
  • Install time: 72 hours
  • Depth: 775 ft / 1,750 ft

TAQA North Cormorant

Impressed Current Cathodic Protection (ICCP) retrofit on the North Cormorant Platform

  • Fixed platforms
  • Installation: ROV
  • Install time: 18 hrs

Houston Ship Channel dock

Project case study: Houston Ship Channel retrofit

  • 5 docks protected
  • Installation: Divers
  • 47 RetroLinks™ installed
  • 16 ICCP anodes installed

Tapis-F & Irong Barat B

Project case study: Anodes replaced on two Malaysian platforms

  • Fixed platforms
  • Installation: ROV
  • Install time: 63 hrs

Tubular Bells

Project case study: Anode retrofit for production pipelines in Mississippi Canyon

  • Water depth: 4,500 ft
  • Installation: ROV

Dana Triton FPSO retrofit

Project case study: Hanging ICCP anode system installed to protect the hull of a floating storage vessel

  • Installation: Topside
  • Unit is storm-recoverable
  • Remote O&M

Offshore wind farm

Project case study: ICCP anode sled to supplement failing anodes on 33 wind turbines

  • Field: 33 tripod turbines
  • Install: < 24 hrs / turbine

Garden Banks 191-A Anode retrofit

Project case study: ICCP anode sleds retrofit on a GOM fixed platform

  • Water depth: 720 ft
  • Installation: ROV
  • Install time: 2 days

BARD Offshore 1 OSS retrofit

Project case study: RetroBuoy™ ICCP anode system for an OSS transformer platform

  • Platform installed 2010
  • Premature anode failure
  • 25-year design life

Enterprise dock anodes

SACP retrofit of dock structure and pilings in Beaumont, Texas

  • Sections of dock, dolphins and piles had insufficient CP
  • Anodes added to supplement existing land-side ICCP
  • Continuity cables added to discontinuous sections

Port of Alaska dock

Cathodic protection retrofit for beams

  • 8 Raparound™ anodes used
  • Divers secured anodes and routed cables

Who Dat retrofit with suspended ICCP anodes

Semi-submersible rig needed short-term CP

  • Most existing ICCP anodes had failed
  • Suspended anode chosen as fastest, lowest-cost option
  • Existing transformer/rectifier used
  • Suspended anode is tethered to prevent damage

The cost of a bad pipe support

California wave park survey

Project case study: California wave park corrosion survey

  • CVI/NDT inspection Done
  • 500,000 sq. ft. + facility
  • 55+ assets Inspected
  • ICCP retrofit recommended

Montara CP test stations

Montara Pipeline fitted with CP test stations

  • Wellhead trees and PLET needed electrical continuity
  • Piggybacks on flowlines lacked continuity
  • Tiebacks were used to ensure electrical continuity
  • RetroClamp™ CP test stations were added

Hydrogen embrittlement study

Project Case Study: Hydrogen Embrittlement Study

  • Study focused on clamp connector
  • Possible gasket embrittlement from CP
  • Internal sections of clamp monitored for CP
  • Polarization of gasket could generate hydrogen

Leman Alpha

Project case study: ICCP anode sled to supplement failing anodes on three structures

  • Install: 12 hours per buoy
  • Depth: 35 M
  • 25-year design life

Tabu, Guntong, Semangkok

Project case study: Anodes replaced during pipeline survey campaign

  • 3 pipelines
  • Installation: ROV
  • Install time: 4 days

Offshore drill stack

Project case study: CP levels monitored and corrected

  • Recap Datalogger
  • CP & Coating Remediation

6 Bay Marchand platforms

Project case study: Anode retrofit of 6 Bay Marchand platforms

  • 6 structures
  • 61 anode strings
  • 5 year life extension

Joliet TLP

Project case study: Anode retrofit for the foundation template of a TLWP in Green Canyon

  • Water depth: 1,760 ft
  • 19 x RetroPods™

Cathodic protection sleds

Heavy-duty anode sleds for high water currents

  • Heavy duty, lower profile sleds
  • For high water current environments
  • High-strength piping
  • 20-year design life

Frying Pan Tower

Project case study: Offshore bed and breakfast platform anode retrofit

  • Civilian owned
  • 12 RetroLinks™

Ship Shoal structures

Project case study: RetroLink™ anode strings on shallow-water assets in the Gulf of Mexico

  • 64 RetroLinks™
  • 25 structures

Zafiro Producer

Project case study: Impressed current cathodic protection of FPSO hull

  • Water depth: 590 ft
  • Dynamic cable
  • 800 Amps CP

Green Canyon

Project case study: Anode sleds installed at Neptune and Shenzi fields

  • Water depth: 4,400 ft
  • Install time: 3 days

Kitchen Lights

Project case study: ICCP anode system for a new platform in Alaska

  • New fixed jacket
  • Cook Inlet, Alaska
  • Impressed current

Brent pipeline

Project case study: Pipeline anode retrofit with mattresses

  • 12 km pipeline
  • Conctrete weight coat
  • 15 year life extension

Shenzi subsea tree

Project case study: SunStation CP monitoring system interrogated by ROV at 4,300 ft

  • Water depth: 4,300 ft
  • 25-year monitoring system
  • No batteries required

Forties field flowlines

Project Case Study: Anode retrofit for the in-field flowlines in the North Sea

  • Install time: 60 hours
  • Depth: 106 m

Duncan Wharf

Project case study: Cathodic protection retrofit using impressed current anode sleds

  • Semi-Arctic temperatures
  • 3,700 AMPS of CP

Cook Inlet Pier

Project case study: Deepwater designs and installs new impressed current pile anode in Alaska.

  • 1,800 AMPS of CP
  • Freeze / thaw resistant

Bahamas loading dock

Project case study: Failing dock anodes replaces with topside anode strings

  • Sacrificial anodes
  • Diverless install

Alba Field

Project Case Study: Anode replacement on a pipeline in EG

  • Installation: ROV
  • Depth: 200 ft
  • Sacrificial anode sled

Neptune Spar

Project Case Study: ICCP anode sled to supplement failing anodes on the hull

  • DEPTH: 1,930 FT

Arklow Bank

Project case study: ICCP anode system for wind farms in the Irish Sea

  • 7 x wind turbines
  • Water depth: 10 m
  • Offshore time: 11 days

Ras Gharib platform

Project case study: Retrofit anode sleds for a fixed platform in the Red Sea

  • Install: Divers
  • Install time: 24 hours
  • Depth: 14 m
  • As left: (-)1.050V vs Ag/AgCl

Lufeng 13-2

Project case study: Two RetroBuoy™ systems for a fixed platform in the South China Sea

  • Platform installed 2005
  • Premature anode failure
  • Depth: 430 ft
  • Supplemental ICCP anodes

Forties Field platforms

Project case study: Nine RetroBuoy™ systems installed to protect four aging North Sea structures.

  • 4 fixed platforms
  • 9 x 450 Amp sleds
  • Install: 12 hours each
  • 20-year design life

South Pass 62-C

Project case study: Two RetroBuoy™ systems replace spent anodes on a 330 ft platform in the Gulf of Mexico

  • Install time: 30 hours
  • Depth: 330 ft

Black Bay platforms

Project case study: Anode strings retrofit on 69 structures in Black Bay, Gulf of Mexico

  • 115 anode strings
  • 22 continuity jumpers
  • Structures: 69
  • Offshore time: 22 days

24 inch methanol pipeline

Project case study: RetroMat™ anode sleds installed on the Atlantic methanol pipeline in EG

  • Local assembly
  • Offshore time: 3 days
  • Length: 2 km
  • As left: -1.025V vs Ag/AgC

Chinook Field PLET

Project case study: Deepwater designs a mini-gateway retrofit in the Gulf of Mexico

  • Continuity jumper
  • Borrowed CP from PLET
  • Custom design
  • 2 week turnaround

Eugene Island 295-A

Project case study: Spent platform anodes replaced with subsea anode strings by divers

  • Installation: Divers
  • Install time: 60 hours
  • Depth: 220 ft

ERWB Jackets

Project case study: Seabed anode sleds retrofit CP on Gulf of Thailand platforms

  • Bridge-connected jackets
  • Water depth: 200 ft
  • Install time: 60 hours
  • Seabed anodes only

Liverpool Bay OSI

Project case study: Hanging ICCP anode system installed to protect the hull of a floating storage vessel

  • Installation: Topside
  • Offshore time: 4 days
  • Unit is storm-recoverable
  • 10 year life extension

Tamar Field

8 inch pipeline

Project case study: RetroLink™ anode strings used to retrofit cathodic protection on 8 inch pipeline

  • Installation: Divers
  • Offshore time: 30 hours
  • Length: 4.5 km
  • As left: -0.998V vs Ag/AgCl

Dudgeon OWF

Project case study: Remote cathodic protection monitoring system installed in the North Sea

  • 4 offshore turbines
  • 32 km offshore

Pipeline Excavation Tool (PET™) installs RetroClamp™

Excavation of shallow buried underwater pipeline near Grand Isle, LA

  • Entire operation done from topside - no divers
  • Took two hours to excavate and install RetroClamp™
  • Whole operation including setup and demob took one day

Case study: Sendje Ceiba FPSO outfitted with RetroBuoy™ ICCP sled

Project case study: RetroBuoy™ ICCP anode system installed to protect the hull of a floating storage vessel

  • Up to 500 amps for 20 years
  • Initial current required: 190 amps
  • Final current required: 404 amps

Gunfleet Sands wind farm anodes

38 monopiles retrofit in Gunfleet Sands

  • 38 monopiles retrofitted in Gunfleet Sands
  • Monitoring added to 6 Gunfleet Sands monopiles
  • Monopile in Lincs gets CP retrofit and monitoring

LINCS wind farm monitoring

Monitoring systems for wind monopiles

  • Wind monopiles without internal coating or CP
  • Long-term monitoring on sampling of structures
  • Corrosion coupons measure wall loss over time
  • Electrical resistance system logs data

Sheringham Shoal anode strings

RetroLink™ anode string tested on wind farm monopile

  • Inadequate CP on external sections of pile
  • Retrofit couldn't use divers or welding
  • RetroLinks™ attached to custom clamps
  • Current monitoring and reference electrodes added

RetroLink™ anode strings installed

Apache’s EC-2-C 4-pile structure in the Gulf of Mexico

  • Six RetroLink™ anode strings installed
  • Depth: 30 feet of water
  • Located in Gulf of Mexico
  • Total time - including travel - 6 hours

Galveston Island Historic Pleasure Pier retrofit

47 RetroLink™ anode strings installed

  • RetroLink™ anode strings installed
  • Anode strings attached with RetroClamps™
  • CP levels verified using Polatrak ®CP Gun™

CP jumper system installed on pipeline

Jumper system provides CP bridge across insulator joint

  • Two 12” RetroClamps™ were installed
  • Pair of 4/0 cables provide continuity
  • ROV installation

ReCap™ data logger installed on BOP stack

Can log CP data for 4 years at 3,000 meter depths

  • System includes high - impedance data logger
  • Two V-String™ zinc reference electrodes used
  • Data recorded every 15 minutes for four years
  • Non-stop data logging of two independent channels

RetroLinks™ installed on multiple assets

Chevron needed CP retrofits on smaller Gulf of Mexico structures

  • A total of five RetroLinks™ installed
  • Platforms, wellheads and pipeline risers
  • Assets spread over various fields

RetroLinks™ installed on Boardwalk Pipeline

Retrofit of shallow pipeline in swamp with RetroLinks™ and RetroClamps™

  • 490 feet of RetroLinks™ installed
  • RetroClamps™ attach anodes to pipeline
  • RetroReader™ used to confirm connection

Anodes installed in chemical plant storage tank

Monitoring system also installed

  • 12 weld-on zinc based anodes installed
  • Potential monitoring panel using zinc reference electrodes was installed

RetroLinks™ installed on Chevron East platform

23 RetroLink™ anode strings were attached

  • RetroLinks™ were attached to 23 horizontal stand-offs
  • Caisson structure in 48 feet of seawater
  • Two Vamp Clamps™ used for electrical continuity
  • 1.5 hours average installation time per anode string

RetroPods™ installed on ExxonMobil platforms in South China Sea

Guntong-F and Irong Barat-C platforms retrofit with RetroPods™

  • Two platforms retrofit
  • 36 RetroPods™ total installed on two platforms
  • Assets in 63 meters of seawater

Retrolinks™ installed on three platforms

Arenque A, B and C get CP retrofits

  • 20 Retrolinks™ used per structure
  • Retrolinks™ were 200 feet in length
  • Protected for at least 5 years

Buffalo Bayou sheet pile survey

Corrosion survey of steel sheet piles in downtown Houston waterway

  • Survey of submerged steel sheet piles
  • Identify multiple discontinuities along piles
  • 6 of 7 TRs were functioning
  • Sampled mud and water for resistivity

160 km pipeline, platform, flare tower retrofit

Located in the Gulf of Thailand

  • 81 RetroSleds™ and 162 RetroClamps™
  • 13 Test stations installed
  • RetroMat-CP Test Station™ used on buried pipeline

CP monitoring installed on marine fueling dock

Açu Maritime Fuel Terminal - TECMA north of Rio de Janeiro State

  • 8 V-String™ reference electrodes and monitoring panel
  • Berth 1: 185m X 32m
  • Berth 2: 110m X 21m

Monitoring system for Australian pipeline

SunStation™, V-String™ and MA-1™ will monitor pipeline and hardware

  • SunStation™ will monitor pipeline CP
  • V-String™ reference electrode attached to SunStation™
  • MA-1™ will monitor Spool Connection Assembly

RetroLinks™ installed on smaller Gulf of Mexico structure

Quarter North Energy’s SS-80A

  • RetroLink™ anode strings installed
  • RetroLinks attached to stand-offs welded to structure
  • Smaller structure in Gulf of Mexico
  • Water depth: 25 feet

CP simulation on an offshore platform

CP modeling was used to provide depolarization timeline

  • Inspection CP data used
  • 3D CAD model used
  • North Sea simulation

Riser base CP modeling

Modeling used to verify 15-year life extension

  • Developed 3D CAD model of asset
  • Used existing CP survey data
  • 15-year life extension

Arabian Gulf pipeline CP retrofit

  • 25 RetroClamps™ deployed
  • 8-inch pipeline from wellhead platform
  • Used to electrically connect anode sleds

64 RetroLinks™ installed on pipelines

  • 64 RetroLinks™ used
  • 26 RetroClamps™ used to attach links
  • Anode strings laid on seabed

RetroLinks™ installed on small structure

  • 14 RetroLinks™ installed
  • 66" lengths
  • Gulf of Mexico

PET™ pipeline excavation and clamp installation

  • 48" and 30" pipelines under 4' to 6' of mud
  • PET™ used to excavate pipes
  • Two RetroClamps™ installed
  • Excavation time: 2 hours

20 RetroLinks™ installed in Gulf of Mexico

  • 20 RetroLinks™ installed
  • 150-foot RetroLink™ length
  • Water depth: 148 feet

I-Rod® 28 years after installation

Dock Cathodic Protection

Anodes systems for Docks, Jetties and Piers

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