Cathodic Protection Solutions Against Corrosion for Offshore Platforms

The Best Method to Prevent Corrosion-Mechanical Damage in Seawater

The most effective approach is to use a combination of protection methods for underwater and water-contact structures: cathodic polarization using sacrificial anodes or impressed current, along with paint coatings.

The intensification of hydrocarbon exploration poses challenges for the industry to develop and implement equipment suitable for operation in aggressive environments (atmosphere, seawater, hydrogen sulfide, pressure, etc.), harsh climates, and icy conditions.

Marine infrastructure—various types of drilling rigs, production platforms, drilling ships—constantly operating in seawater, are highly exposed to the risk of corrosion. Coatings and insulation alone cannot ensure sufficient protection, and the complexity of underwater repairs makes corrosion control especially relevant.

One of the most promising methods of protecting steel in seawater from corrosion-mechanical damage is cathodic protection. For surfaces in contact with seawater, the most optimal solution is to apply several protection methods simultaneously: cathodic polarization (sacrificial or impressed current) and paint coatings.

PSS Corporation develops both cathodic protection methods: sacrificial anode systems and impressed current cathodic protection (ICCP).

Protection of Subsea Equipment from Corrosion

Expensive seabed oil and gas equipment—manifolds, wellheads, flowlines, and pipelines—requires corrosion protection.

For subsea structures, sacrificial anodes are used in combination with coatings. PSS Corporation manufactures D-shape protruding aluminum anodes.

A sacrificial anode is a casting made of aluminum alloy with zinc, with a steel core. Anodes are produced in various sizes and cross-sections depending on design calculations. They are installed for the full service life of the structure.

Protection potential: -1.05 V
Current capacity: 2500 A*h/kg

Sacrificial Anode Protection of Drilling Platforms

On floating platforms, sacrificial protection is primarily used for isolated ballast compartments, while the hull itself is protected by ICCP.

Typical anodes for this application are aluminum and zinc trapezoidal weld-on anodes. Anodes are mounted onto the protected structure to form a reliable electrical connection, so all corrosion processes occur on the anode. Anodes are cost-effective, require no maintenance, and do not need a power supply.

All types of sacrificial anodes produced are made of zinc and aluminum alloys according to ISO and International Association of Classification Societies standards. A flexible casting system allows for various sizes and shapes, and parameters can be customized upon request.

Cathodic Protection of Drilling Platforms

To effectively protect marine infrastructure, impressed current cathodic protection (ICCP) is used alongside coatings. In recent years, the Advanced Development Department has designed a comprehensive set of equipment for marine corrosion protection.

With impressed current, any object with an electricity source can be protected.

Advantages of ICCP for platforms:

• Full suppression of corrosion in hull plating and welds
• Reduced need for corrosion allowance in hull design
• Remote monitoring and control

Transformer Rectifiers for Offshore Platforms

The PSS Pulse Rectifier is designed for ICCP of marine structures by shifting the metal’s potential. This makes the surface equipotential, ensuring only cathodic processes occur across the structure.

Stations are produced in various power levels and configurations.

Impressed Current Anodes for Offshore Platforms

Impressed current anodes are designed for ICCP systems for the hulls of platforms and ships. They discharge protective current into the water. For floating platforms, anode assemblies are low-solvent anodes installed in the hull of the platform. Anodes are installed on ships, vessels and watercraft operated in unlimited areas of navigation.

Ti Hull Anode – Active part made of titanium alloy with a protective galvanic coating, enclosed in a polymer housing.
MMO/ Ti Hull Anode – Designed for Arctic operation. Made of titanium alloy, coated with platinum group oxides, protected with a titanium plate, and placed in a cofferdam—a sealed steel cylindrical housing with a wall thickness of at least 10 mm.

Reference Electrodes for Offshore Platforms

Used to measure potential with ohmic component and polarization potential without it (protective potentials) of metal structures. Also used in automatic control and regulation systems for ICCP units.

Marine reference electrodes can be silver/silver-chloride or zinc, and may be manufactured in cofferdams for Arctic use.