Way Ahead In Corrosion Control

V-String zinc reference electrode

V-String has a rugged conductor with a strong overbraid of polyester fibers for monitoring platform CP


The V-String™ zinc reference electrode has a rugged conductor with a strong overbraid of polyester fibers

The Polatrak® V-String™ electrode is a low-cost zinc reference electrode designed for offshore platform and pipeline monitoring. The ultra-rugged construction and ease of installation make this a viable general-purpose cathodic-protection monitoring retrofit system, or as a supplement to other Polatrak® monitoring instruments such as the DR-2™ dual reference cell, or the MA-1™ monitored sacrificial anode. The V-String's accuracy is +/- 0.02 V, which is perfectly acceptable for a general-performance monitor.

The electrode wire consists of a galvanized-steel aircraft cord with a PVC jacket and a polyester-fiber overbraid. This combination makes the electrode almost indestructible. V-Strings™ have been installed on dozens of types of structures, from platforms and offshore pipelines to shallow-water wind farms.

Interrogating the electrode can be done in several ways. If installed on a traditional structure, the conductor can be wired to the surface and connected to a monitoring panel. In some instances, the panel can also be wired to a satellite transmitter. For subsea assets and offshore pipelines, the V-String™ can be interrogated by ROV using a SunStation™ subsea readout.


Project experience

PanYu 30-1

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

  • Water depth: 200 m
  • Fixed monitoring

Tubular Bells

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

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

The cost of a bad pipe support

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

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

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

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

TAQA North Cormorant

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

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

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

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

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

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

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

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

LAF-1 & 2 Platforms

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

  • Installation: ROV
  • Impressed current anodes

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

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

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

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

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

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

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

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

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

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™

RetroPods™ installed on wellheads and SUTA

Three anode sleds protect subsea equipment

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

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

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™

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

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

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

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

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

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

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

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

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

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

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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