Platform Deployed CP Retrofit: A Cost-Effective Solution For Extending Cathodic Protection Life of Offshore Platforms

The Challenge

Extension of the cathodic protection (CP) life of an existing offshore platform is a challenging but mandatory task to maintain the adequate CP level and avoid marine corrosion. Conventional CP retrofit methodologies require underwater intervention and vessel, which are very costly, especially for structures that are located in saturation diving depth. In partnership with Galvotec Corrosion Services (GCS) of the USA, IEV is launching two Platform Deployed CP Retrofit technologies as part of its portfolio of corrosion control solutions to enable its offshore oil and gas clients to lower the cost of extending cathodic protection life on existing facilities.

Platform-Deployed ICCP Retrofit Solution

The Vertical Tensioned Anode or VTA, is a hanging ICCP system that can be installed and deployed within the perimeter of a jacket by riggers and welders within days at site. The elimination of ROV/diving operation and associated vessel costs result in cost savings in excess of 50% compared to conventional anode retrofit solutions such as installation galvanic anodes by divers or anode sleds by ROV.

The string design allows the current generated from each of its platinum niobium anodes molded along the VTA string to be individually powered with its own cable from the rectifier, so the output of each anode can be monitored and controlled. The number of strings is determined by the total surface areas of each specific structure. With more than 40 years of history, the VTA is built to withstand extreme weather conditions and provide 20 years or more CP protection.

Platform-Deployed Galvanic Anode System

Galvo-String is a hanging galvanic anode system that can be retrofitted onto ageing jackets to extend its cathodic protection (CP) life by 5 to 10 years. IEV combines CP and structural engineering designs to meet rigorous ocean storm conditions and varying water depths. All CP and engineering calculations are performed according to DNV and API standards.

Suspended at the top end from a pad-eye or clamp and anchored at the bottom end at the seabed by a clump weight, the Galvo-String is made up by a series of Aluminum anodes that are connected together by shackles. Current passes from one anode to another and all the way to the pad-eye through continuity jumper bonds.

Storm loads on each Galvo-String is analysed and its deflection envelope is determined to prevent any contact with surrounding structural members. Site installation is performed by welders and riggers and takes only a few days to complete, thus reducing the cost of conventional CP retrofit by more than 50%.

For more details please download the following documents :

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