In the vastness of the ocean, the safety and stability of offshore oil rigs and steel piles of jetties are of paramount importance as critical facilities for human exploration of marine resources. However, the complexity of the marine environment presents many challenges to these facilities, the most prominent of which is corrosion. To meet this challenge, cathodic sacrificial anode protection measures have been developed to provide effective protection for offshore oil rigs and jetty steel piles.
The core principle of cathodic protection is the use of potential differences to control the corrosion of metals. By reducing the corrosion potential of the metal structure below the anodic limit, a protective film can be formed on the metal surface, preventing corrosion from occurring. This method of protection is economical, environmentally friendly and durable, and is therefore widely used to protect steel piles on offshore oil platforms and wharves.
For offshore oil rigs, a cathodic protection sacrificial anode system typically consists of a sacrificial anode, a reference electrode, a test cable and a test instrument. These components work together to provide comprehensive protection for the rig. During the installation process, the platform must first be visually inspected underwater to determine the location and number of anodes to be installed. Divers then perform underwater cabling, calibration and anode welding. These steps securely attach the sacrificial anodes to the platform for long-term protection.
Similar to offshore oil rigs, cathodic protection of steel piles in terminals is equally important. The stability and durability of quay steel piles, as key components supporting the quay structure, are critical to the safe operation of the quay. Sacrificial anode measures for cathodic protection are also applicable to the protection of quay steel piles. By installing sacrificial anodes, a protective film can be formed on the surface of the steel piles, effectively preventing corrosion.
The choice of coating is also critical when implementing cathodic protection sacrificial anodes. Common coatings include aluminum-zinc alloys and magnesium-zinc alloys. These coatings have excellent electrochemical properties and corrosion resistance, and can provide long-term protection for metal structures. The selection of the protective agent must be based on a comprehensive consideration of the specific environmental conditions, structural characteristics and service requirements to ensure that the protective effect is maximized.
The necessity of cathodic protection sacrificial anode protection method for drilling platforms
Marine bridges, river bridges, and large seaport terminals are near-seaport structures made of steel or partially reinforced concrete. There are fixed structures (e.g. steel pipe piles, steel sheet piles, trestle bridges, artificial islands, etc.) and floating structures (e.g. barges, floating docks, floating wharves, water drums, etc.). ), and they are subject to corrosion by seawater or marine media and humid atmosphere, especially corrosion in the ocean, estuaries and near-shore environments, and the average corrosion rate can be as high as 0.12-0.2 mm/a, which can lead to rapid thinning of steel structures, short-term perforation and weakening of its bearing capacity, affecting the safe operation within the prescribed design life. Therefore, effective corrosion protection measures must be applied to them. Among them, cathodic protection is one of the most effective means of protecting steel structures in water. A large number of engineering practices at home and abroad have proved that: proper anti-corrosion design and application of cathodic protection technology can reduce the corrosion of these steel structures to below 0.02mm/a and extend their service life by more than double. The corrosive environment of modern marine bridges and large port terminals is more complicated than that of previous offshore projects, and the requirements for safe operation and service life are higher, resulting in more stringent and comprehensive design requirements for corrosion prevention. The cathodic protection design is the basic guarantee and key to grasp the protection of steel structure, ensure its safe operation and achieve the design life. It should make full use of all the past experience and data of anti-corrosion of ships and offshore projects, and further develop and innovate the technology to reach a new level of cathodic protection design.
Sacrificial Anode Installation Procedure
Pre-construction preparation: handling the relevant procedures for entering the factory, setting up the workshop, technical briefing, safety training.
Underwater visual inspection and calibration of new anodes and drawing numbering of anodes.
A diver prepares a measuring cable by wiring it underwater with a pre-designed measuring cable. The water crew simultaneously calibrates the boat to pinpoint the position.
Surface cleaning of the anode welding area
Clean the surface of steel structure of grease, dirt, rust oxidized skin, growth of water organisms to ST2.5.
Underwater transport and temporary fixation of anodes.
The ship's crew uses the ship's lifting gear to place the prepared and numbered sacrificial anodes in the predetermined position along the guides.
Underwater Welding Anodes
