X
Bridge is an important infrastructure in national economic construction. Reinforced concrete structure is widely used in bridge. Chloride ion from seawater is an important factor that causes premature corrosion failure of steel tubular pile structure of bridge. Taking economical and effective measures to prevent and control corrosion damage of bridge steel pipe pile structure is a research topic of common concern in all countries. Cathodic protection is an electrochemical anti-corrosion technology to prevent metal corrosion. Cathodic protection is a technology that can have an important impact on the corrosion process that causes the deterioration of bridge structures.
In order to improve the safety protection effect of the cathodic protection system, the cathodic protection system is tested regularly, and the problems existing in the cathodic protection system are found in time and dealt with in time. To take the necessary maintenance measures to improve the effect of the cathodic protection system, in order to achieve the effect of cathodic protection, extend the service life of the protective structure, to prevent the corrosion of metal pipes, cathodic protection has two forms, cathodic protection of sacrificial anode and cathodic protection of impressed current. To detect the effect of cathodic protection, find out the failure of cathodic protection measures in time, and take necessary remedial measures to improve the effect of pipeline cathodic protection. The way of system detection, according to different cathodic protection measures, the potential of each part is detected, and the operation of the cathodic protection system is evaluated by comparison.
The current marine facilities (ports, piers, breakwaters, etc.) are mostly composed of steel pipe piles or steel sheet piles, which are subjected to corrosion by water medium and humid gas due to long-term exposure to seawater, causing structural collapse and serious affecting the safe use of ports and piers. Therefore, it is extremely important to protect these steel structures from corrosion.
The principle of electrochemical corrosion: when a steel-made ship body comes into contact with seawater, an electrical potential is generated, leading to the occurrence of electrochemical corrosion. Therefore, in order to minimize the contact between the ship body and seawater, an anti-rust paint is used to isolate the ship body and seawater. However, the propeller, rudder, or part of the ship body that comes into contact with seawater due to damage to the ship body cannot be completely avoided. Therefore, part of the ship body that comes into contact with seawater will undergo electrochemical corrosion, and the degree of corrosion varies depending on the electrolysis conditions.
An undersea pipeline is an installation of pipelines under the sea, which can be divided into the following categories: subsea pipelines, coastal pipelines, deep sea pipelines, including pipelines for the transportation of oil, natural gas, seawater, freshwater, and wastewater. On average, the low electrical resistance of seawater simplifies the operation of cathodic protection for undersea pipelines. The most suitable anode for protecting undersea pipelines is the bracelet-type anode. The factors that affect the current demand in seawater are temperature, salinity, and currents. Temperature is usually the most important factor. Bracelet-type anodes for undersea pipelines are usually arranged along the pipeline with a certain interval. The standard material for bracelet-type anodes is aluminum-zinc-indium, but zinc anodes are sometimes used. If the surface temperature of the pipeline exceeds 50°C, bracelet-type zinc anodes are not suitable. When the pipeline is in a high-temperature environment, we recommend using other types of anodes that are arranged along the pipeline and connected to the pipeline with a cable.
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.
The petrochemical plant area and oilfield buried metal structures mainly include buried metal pipelines, the copper-clad steel grounding grid of the oil storage tanks above ground, etc.
In natural environments, soil contains water, oxygen, acid, alkali mineral salts, and microorganisms, which can cause corrosion of metal pipelines. The main function of the pipeline coating is a physical barrier to separate the metal substrate from the external environment and prevent metal from interacting with the surrounding environment. However, there are two reasons that can cause metal corrosion: one is the inherent defects of the coating, such as pinholes; the other is the inevitable damage to the coating during construction and operation, which exposes the metal to a corrosive environment. The presence of these defects leads to the phenomenon of a large cathode and a small anode, which accelerates corrosion at the damaged coating site and causes pipeline corrosion and rupture, leading to safety accidents. Many years of practice at home and abroad have proved that the most effective corrosion control measure is the combination of coating and cathodic protection.
The condenser, also known as a condenser, is used to condense the exhaust steam from a turbine into water, which is the most important auxiliary equipment for a steam turbine generator. The water chamber of the condenser is usually made of cast iron or carbon steel, and the heat exchanger tubes are made of brass or other copper alloys. The condensing tubes may be made of aluminum bronze, white bronze, or titanium.
A tank is a large container used to store crude oil or other liquids, consisting of tank walls, tank roof, tank bottom, and accessories. The tank's cathodic protection includes internal cathodic protection and external cathodic protection. Internal cathodic protection can usually be used in tanks, and external cathodic protection can also be used for tanks with longer protection life requirements. The bottom of the tank is usually protected by external cathodic protection due to the difficulty of replacing sacrificial anodes and the requirement for a longer service life.
