gaswewe As an important strategic material, oil plays an irreplaceable role in industrial development. Due to the particularity of materials, we often lose oil due to corrosion during transportation and storage. Therefore, it is necessary to enhance the anti-corrosion characteristics of pipelines and storage tanks, to ensure that the transportation and reserves of oil are stable.
Causes of Corrosion for Oil Pipelines and Storage Tanks
Part 1
As an important energy source, oil is viscous and dark brown in appearance, and it is liquid. Because we widely use oil in various fields such as energy supply, industrial manufacturing and other industries, we also called it the blood of the industry. In the war and daily national development, we called oil the primary strategic energy material, which shows the importance of oil. With the rapid development of industrialization, the demand for oil is increasing year by year. As one of the major oil consumers, China has extensive demand for oil, so the transportation and storage of oil are very strict.
Because we use oil pipelines and storage tanks frequently and for a long time, and we make most of them of metal, but as a kind of natural gas energy, the oil itself contains a small amount of sulfide and other components, which will cause certain corrosion to metals. From the global point of view, due to the large demand for oil resources and the fierce competition among countries for oil resources, in order to increase oil production and meet the needs of national development for oil, oil fields often add many additives to oil, resulting in more and more sulfur content in oil, which aggravates the corrosion of pipelines and leads to the poor performance of pipelines and storage tanks service life.
Part 2
We make most of China’s oil pipelines are of metal materials, but environmental and climatic factors often influence these materials in the process of use. The interstitial reaction will occur between them, leading to corrosion of pipelines and storage tanks. Therefore, the pipeline construction method can not alleviate the corrosion of the pipeline, whether it is deep-buried construction or overhead construction, it will cause the gradual corrosion of metal. The main reason for the corrosion reaction of pipelines is the chemical reaction and electrochemical reaction between metals and various factors such as environment and climate.
Anti-corrosion Measures for Oil Pipelines
1. Protective Film Coating Anticorrosion
Part 1
Anti-corrosion of the protective film essentially refers to the optimization of the outer environment of an oil pipeline through the appropriate chemical materials, so as to isolate the oil pipeline from the outside world and reduce the damage caused by external corrosion factors to the oil pipeline, thus achieving the anti-corrosion treatment of the oil pipeline. Generally speaking, anti-corrosion protective layer is one of the most common protection methods in oil pipeline anticorrosion. This scheme has the advantages of low price and operation, so people have widely used in actual oil pipeline anti-corrosion protection.
Although this method is practical, we still have many problems to further improve in practical application, among which the most important problem is that we easily damage the coating. In the actual transportation process of oil, because the pipeline often collides and rubs with external things, the time will cause the wear and tear of oil coating. Therefore, it reduce the service life of the coating and the anti-corrosion effect can not reach the ideal goal. In order to reduce the occurrence of this situation, it is necessary to carry out further treatment according to the use environment and choose appropriate protection methods.
Part 2
First, we further optimize the raw materials of the coating so that the coating can achieve the best anti-corrosion protection effect as much as possible. Therefore, in actual anti-coating materials, we often use two-layer polyethylene, three-layer polyethylene and other components. The optimized fuel is processed again in coating technology for water pipelines and storage tanks, so as to ensure that the coating can meet the protection needs of pipelines and storage tanks as much as possible. In the practical application of anti-corrosion of PetroChina pipeline and storage tank, it is often necessary to implement three-layer coating protection treatment.
First, the innermost coating of the pipeline and storage tank is usually an epoxy powder. The middle layer is adhesive and the outermost layer is a polyolefin. Three-layer protective coating technology can effectively enhance the anti-corrosion of oil pipelines to the maximum extent, and finally reduce the damage of anti-corrosion coating caused by collision and extrusion in the actual process, thus reducing the anti-corrosion effect of oil pipeline storage tanks. It can effectively avoid the economic loss and danger caused by the corrosion of oil pipelines and storage tanks.
2. Cathodic Protection
We have used Cathodic protection technology for a long time, and it first appeared in the 1930s. The rapid development of industry greatly increased the demand for oil. So in the development of science and technology, with each passing day, we began to use cathodic protection technology in the protection of pipelines and storage tanks. We have widely used this technology in the 1950s, and the development of its protection technology has already developed a mature operating system.
The outstanding advantage of this technology lies in coating protection. This technology can make up many defects in it and improve it. With the technology, it can make up for the original promotion and protection technology, so as to improve the anti-corrosion effect and safety of storage tanks in use. The technology is mature and clear. The specified standards and rigorous and efficient process standards are also clear. We apply the method in practice.
It is easy to operate at a cheap price and has obvious advantages in environmental protection. It will not damage or pollute the underground environment. Besides, it can protect the current environment of pipelines and storage tanks, which drains stray currents.
3. Anticorrosion of Active Metals
Among the causes of corrosion in oil pipelines and storage tanks, chemical reactions cause most of them. Therefore, studying the related chemical reactions that lead to corrosion of water pipelines and exploring its formation mechanism can slow down the corrosion situation. The main chemical reaction refers to the family material, which is positive in the chemical reaction. Its nature is relatively active, so when the electrons are lost and the cation is generated, the anode will be formed.
The same anions will also produce corresponding effects, causing the cathode to form, which will lead to the effect of the pipeline similar to the battery, thus accelerating the corrosion of the pipeline. According to this chemical reaction principle, we can improve the pipeline. For example, adding metal elements that are more active than pipeline metals to the pipeline can make the elements oxidized to form cations at first, thus reducing the chemical reaction of the oil pipeline itself. It can reduce the oxidation situation of the pipeline and play the role of delaying corrosion and protecting the pipeline.
4. External anticorrosion of upper pipelines
External anticorrosion of pipelines refers to painting the pipeline with antirust paint, which generally includes two kinds of primer and topcoat. Primer has the characteristics of anti-corrosion and strong adhesion. Aluminum powder paint with strong toughness is often used as a top coat, which should be applied according to strict working procedures. This anti-corrosion technology is mainly used to reduce the negative effects of environmental geology and climate on the pipeline. The protective layer is used to protect the pipeline physically, so as to reduce the corrosion on the outside, but the inside of the pipeline can’t get the corresponding protection effect. Therefore, while using the outer coating for protection, it is also necessary to deal with the corrosion on the inside.
Anticorrosion of Oil Storage Tanks
1. Anticorrosion in Oil Storage Tanks
Part 1
In the anticorrosion of oil storage tanks, corrosion protection in the tank is the most important part. In the actual anti-corrosion operation, we usually fill the corresponding storage tanks according to different kinds of crude oil. For example, different crude oils such as gasoline and diesel oil need different storage tanks. Generally, storage tanks include roof tanks and floating roof tanks. Different kinds of storage tanks have different anti-corrosion treatments. According to practical experience, in-tank anti-corrosion is the most important link. Because in-tank is the direct contact part of the petroleum liquid, there will be different anti-corrosion technologies according to the different contact parts in-tank. For example, some places are mainly subject to electrical corrosion and some places are subject to chemical corrosion.
Part 2
Generally speaking, gas often corrod the parts in direct contact with petroleum liquid. The corrosive gas is mainly acidic gas, and some components are carbon dioxide or water vapor brought in during the process of petroleum input. These components will chemically react with some volatile gases of oil, producing certain acid gases, which will lead to the corrosion of the top of oil tanks. We call this process an oxygen depolarization reaction, and this chemical reaction will cause serious corrosion to the top of storage tanks.
According to the actual corrosion situation, the gas corrosion effect is even much more serious than that of tanks directly contacting with oil liquid, even more than 10 times higher than that of the latter. There is also a situation that the oil will collide and shake due to the instability of the tank during oil transportation. This situation will lead to more volatile gas in the oil. The place where volatile gas and liquid blend will cause more serious corrosion, even more, serious than the single gas corrosion.
Part 3
In addition to the position of the tank top which is not in direct contact with the oil, the places such as the tank wall and the tank bottom which are in direct contact with the oil will also produce corresponding corrosion. Generally speaking, the long time of the tank wall and the tank bottom will lead to the corresponding chemical property changes. Unlike the tank wall, the corrosion factors of the tank bottom are more complicated, such as the corrosion caused by the accumulation of water molecules and the corrosion caused by the accumulation of various impurities in the oil. This is not only chemical corrosion but also electrochemical corrosion.
Generally speaking, the most important corrosion is chemical corrosion. In view of this situation, the coating anti-corrosion technology is the most commonly used one. In terms of material selection, materials with acid and alkali corrosion resistance and strong adhesion should be selected. Among them, epoxy coatings are widely used, and carbon nanopolymers are widely used in the anti-corrosion treatment of light storage tanks because of their excellent strong temperature resistance.
In addition, we can use cathodic protection technology to electrify and prevent corrosion of storage tanks. In addition, we should note that in the research and development stage of the design storage tank. Firstly, the frequently corroded or severely corroded parts in the storage tank should be cut off for strengthening treatment, such as increasing the material thickness of metals, so as to prolong the service life of the storage tank. Regular maintenance inspection should be carried out during the use of the storage tank to check the reduction of corrosion in the tank and the economic losses and accidents caused by corrosion.
2. External Anticorrosion of Storage Tanks
Part 1
Tank anticorrosion includes not only in-tank anticorrosion but also external-tank anticorrosion. The corrosion of the outer wall of the storage tank mainly comes from the air environment, which we regard it as atmospheric corrosion. In practice, the regional climate and environment that the tank passes through often relat e to the degree of corrosion outside the tank wall , and environmental factors such as air quality also influence it . For example, in China’s coastal cities, the moisture and moisture in coastal cities are obviously higher than those in inland areas, and the coastal areas are of developed economy, with a high degree of industrial development. Their air pollution is also relatively high.
Part 2
All kinds of pollutants in the air, such as sulfur dioxide and carbon dioxide, are higher than those in inland areas. Therefore, these air pollution components will corrode the outer wall of the storage tank, so it is necessary to coat the materials outside the tank. To choose waterproof paint, grease and other materials, you can also choose acid-proof epoxy coatings. In addition. In order to improve the quality of oil and choose corrosion-resistant materials, when we store oil in tanks, it is necessary to properly handle it, minimize the corresponding corrosive additives, and try to choose the tank materials with good wear resistance, so as to avoid the cracking phenomenon caused by pitting corrosion and stress corrosion which often occur in stainless steel materials.
Conclusion
As one of the most important strategic materials for the development of petroleum industrialization, it is of great significance for national economic development and national security. Therefore, doing this kind of work well in the transportation and storage of oil pipelines is important to work to maintain the safety of the strategic oil storage task, ensuring the needs of national economic development, which we must give corresponding attention. In order to reduce the corrosion of oil pipelines and storage tanks, it is necessary to choose various protection methods according to the actual situation. In addition, in terms of energy, it is necessary to improve the quality of the oil itself, and select materials with good anti-corrosion effect for manufacturing pipes and storage tanks.
