X
An offshore oil drilling platform is a marine metal structure mainly used for drilling wells in the ocean. It is equipped with drilling, power, production, communication and navigation equipment, as well as safety and life-saving facilities for personnel. The reliability and safety of offshore platforms are of great importance. As the depth of the sea where the platform is located becomes deeper, the platform becomes larger, the structure becomes more complex, and the investment also increases. In order to effectively develop offshore oil, provide safety guarantees for production, it is necessary to control corrosion on the platform. Cathodic protection is an important method to prevent marine structures from being corroded by seawater. It can effectively extend the life of offshore drilling platforms in seawater, and the protective effect of cathodic protection on offshore drilling platforms has been confirmed by many practices.
A wind farm is composed of offshore structures, usually located in shallow water areas ranging from 2 to 30 meters. By using aluminum-zinc-indium alloys, the structural parts located in the water and submerged areas can be protected from corrosion. The cathodic protection system can have a service life ranging from 15 to 50 years, depending on the application. The anode can be easily installed on the structure before or after the pile installation, depending on the type of pile (jacket, tripod, pipe pile, etc.). The anode can be installed using clamps or overlay plates to avoid damaging the coating.
The anti-corrosion of drilling and oil production platforms adopts a combined method of coating and cathodic protection. The steel pipe piles or steel sheet piles underwater and in splash zones are protected by cathodic protection, while the parts above the average low tide line are protected by coating. Cathodic protection can be sacrificial anode cathodic protection, forced current cathodic protection, or a combination of both, depending on the structure, corrosion environment, power supply, equipment reliability, operational management, and other factors that jointly determine the economic feasibility and protective effect.
For the corrosion protection of offshore drilling and oil production platform facilities, a thick-coated overlayment should be applied for the above-tidal-zone areas, while for the underwater parts, most of them were protected by forced-current cathodic protection in the past. With the improvement of aluminum alloy anode performance and the accumulation of cathodic protection experience parameters, the selection of sacrificial anode cathodic protection for offshore drilling and oil production platforms requires consideration from the following aspects: the reliability of the protection system, the influence of adjacent structures, the required current for protection, the complexity of the structure, the service life of the structure, and environmental conditions, etc.
Cathodic Protection by Electrolysis:
1. Calculate the protected area, in addition to calculating the area of seawater and mud below the average low tide, the area of tidal zone and the area of adjacent structures should also be included.
2. Calculate the protective current: Calculate the required protective current for cathodic protection system based on the protected area and initial or maximum protective current density. Take 1.25-1.5 times the total required current as the total required current.
3. Selection and Number of Anode Bars: The auxiliary anode bars used for forced current cathodic protection at ports and wharves are high silicon cast iron anodes and precious metal oxide anodes.
