Corrosion in Oil Pipeline and Storage Tank
Recognized as a vital strategic resource, oil holds an indispensable position in industrial development. Owing to the distinctive nature of the material, corrosion frequently results in oil loss during transportation and storage. Thus, it becomes imperative to bolster the anti-corrosion features of pipelines and storage tanks to ensure the stability of oil transportation and reserves.
1. Protective Film Coating Anticorrosion
The protective film anti-corrosion involves optimizing the external environment of an oil pipeline using chemical materials to isolate it from external factors, reducing damage caused by corrosion, and achieving effective anti-corrosion. While cost-effective, this method faces challenges, notably in coating durability. Collisions and abrasions during oil transportation can lead to coating wear, reducing its lifespan and compromising anti-corrosion efficacy. To address this, material selection for coatings needs careful consideration. Utilizing coatings such as two-layer polyethylene or three-layer polyethylene can enhance anti-corrosion protection. PetroChina often employs a three-layer coating process for pipelines and storage tanks, comprising an inner epoxy powder coating, a middle adhesive layer, and an outer polyolefin layer. This optimized approach minimizes economic losses and safety risks due to corrosion.
2. Cathodic Protection
Cathodic protection technology, developed since the 1930s, gained prominence in the 1950s for safeguarding pipelines and storage tanks from corrosion. This mature technology effectively supplements coating protection, rectifying its flaws and improving anti-corrosion effectiveness. With well-established standards and an efficient operational system, cathodic protection ensures safety and environmental benefits, preventing damage or pollution to the underground environment. Moreover, it guards against stray currents, providing a cost-effective and environmentally friendly solution.
3. Anticorrosion of Active Metals
Addressing chemical reactions as a major cause of corrosion, combating it involves studying related reactions and understanding the formation mechanism. By recognizing that more active metal elements accelerate corrosion, introducing metals more active than those in the pipeline can mitigate chemical reactions, delaying corrosion and offering protective benefits.
4. External Anticorrosion of Upper Pipelines
External anticorrosion involves applying anti-rust paint to pipelines, typically in primer and topcoat layers. The primer boasts anti-corrosion and strong adhesion properties, while aluminum powder paint serves as a durable topcoat. This method protects pipelines from environmental factors but doesn't address internal corrosion. Combining external coating with internal corrosion treatment ensures comprehensive protection.
Anti-corrosion of Oil Storage Tanks
1. Internal Anti-corrosion in Oil Storage Tanks
In the anti-corrosion process of oil storage tanks, safeguarding against corrosion within the tank is paramount. Operational practices involve allocating specific storage tanks based on the type of crude oil, such as gasoline or diesel oil, with variations in anti-corrosion treatments for roof tanks and floating roof tanks. The in-tank anti-corrosion process holds utmost significance, considering it is the direct contact point for petroleum liquid. Various anti-corrosion technologies are applied based on the specific areas within the tank experiencing contact. Gas corrosion, primarily from acidic gases like carbon dioxide or water vapor introduced during petroleum input, poses a significant threat to the top of oil tanks. This gas-induced corrosion, termed oxygen depolarization reaction, can be more severe than direct contact corrosion. During oil transportation, instability in the tank can lead to collisions and shaking, resulting in increased volatile gas in the oil and intensified corrosion, surpassing that of gas corrosion alone. Apart from areas not directly in contact with oil, such as the tank top, positions like the tank wall and tank bottom experience corresponding corrosion due to direct contact with oil. The tank wall undergoes chemical property changes over time, while the tank bottom faces complex corrosion factors, including water molecule accumulation and impurity buildup in the oil, leading to both chemical and electrochemical corrosion. Coating anti-corrosion technology, with materials like epoxy coatings known for acid and alkali corrosion resistance, is widely employed. Additionally, cathodic protection technology can be used to electrify and prevent corrosion. In the design stage of storage tank development, attention should be given to parts prone to corrosion, reinforcing them through measures like increased metal thickness to prolong the tank's service life. Regular maintenance inspections during tank use are crucial to monitor corrosion reduction, economic losses, and potential accidents.
2. External Anti-corrosion of Storage Tanks
Tank anti-corrosion encompasses both in-tank and external-tank protection. External tank corrosion primarily stems from atmospheric factors, known as atmospheric corrosion. The degree of corrosion on the tank wall's outer surface is closely tied to the regional climate, environment, and air quality. Coastal cities in China, for instance, face higher humidity, industrial development, and air pollution, leading to increased atmospheric corrosion. To counter this, materials for external tank coatings should be selected based on factors such as waterproofing, grease, and acid-resistant epoxy coatings. Enhancing oil quality involves minimizing corrosive additives during storage, selecting corrosion-resistant materials, and addressing wear resistance to prevent issues like cracking due to pitting corrosion and stress corrosion in stainless steel materials.
Conclusion
As one of the vital strategic resources driving the advancement of petroleum industrialization, the transportation and storage of oil pipelines bear immense significance for national economic development and security. Ensuring the safety of strategic oil storage tasks is crucial to meet the requirements of national economic progress. To mitigate the corrosion of oil pipelines and storage tanks, it becomes imperative to adopt suitable protective measures tailored to the specific circumstances. Furthermore, enhancing the quality of the oil itself and employing materials with robust anti-corrosion properties in the fabrication of pipes and storage tanks are essential measures in the realm of energy management.
Causes of Corrosion in Oil Pipelines and Storage Tanks
Oil, a crucial energy source often referred to as the lifeblood of various industries, plays a vital role in energy supply and industrial manufacturing. Given its significance, the transportation and storage of oil, facilitated by pipelines and storage tanks, are subject to stringent regulations. These infrastructures, predominantly constructed from metal materials, endure prolonged and frequent usage. However, the inherent corrosive nature of oil, containing sulfides and other components, poses a challenge to the longevity of metal structures.
Globally, the escalating demand for oil resources, coupled with fierce international competition, has driven oil fields to incorporate various additives, resulting in increased sulfur content in oil. This heightened sulfur content exacerbates the corrosion of pipelines, adversely affecting their performance and service life.
In China, where oil consumption is substantial, oil pipelines primarily consist of metal materials. Environmental and climatic factors, coupled with interstitial reactions between metals, contribute to the corrosion of pipelines and storage tanks. Whether employing deep-buried or overhead construction methods, both are susceptible to the gradual corrosion of metal structures. The primary causes of pipeline corrosion are rooted in chemical and electrochemical reactions between metals and environmental factors.
Anti-corrosion Measures for Oil Pipelines1. Protective Film Coating Anticorrosion
The protective film anti-corrosion involves optimizing the external environment of an oil pipeline using chemical materials to isolate it from external factors, reducing damage caused by corrosion, and achieving effective anti-corrosion. While cost-effective, this method faces challenges, notably in coating durability. Collisions and abrasions during oil transportation can lead to coating wear, reducing its lifespan and compromising anti-corrosion efficacy. To address this, material selection for coatings needs careful consideration. Utilizing coatings such as two-layer polyethylene or three-layer polyethylene can enhance anti-corrosion protection. PetroChina often employs a three-layer coating process for pipelines and storage tanks, comprising an inner epoxy powder coating, a middle adhesive layer, and an outer polyolefin layer. This optimized approach minimizes economic losses and safety risks due to corrosion.
2. Cathodic Protection
Cathodic protection technology, developed since the 1930s, gained prominence in the 1950s for safeguarding pipelines and storage tanks from corrosion. This mature technology effectively supplements coating protection, rectifying its flaws and improving anti-corrosion effectiveness. With well-established standards and an efficient operational system, cathodic protection ensures safety and environmental benefits, preventing damage or pollution to the underground environment. Moreover, it guards against stray currents, providing a cost-effective and environmentally friendly solution.
3. Anticorrosion of Active Metals
Addressing chemical reactions as a major cause of corrosion, combating it involves studying related reactions and understanding the formation mechanism. By recognizing that more active metal elements accelerate corrosion, introducing metals more active than those in the pipeline can mitigate chemical reactions, delaying corrosion and offering protective benefits.
4. External Anticorrosion of Upper Pipelines
External anticorrosion involves applying anti-rust paint to pipelines, typically in primer and topcoat layers. The primer boasts anti-corrosion and strong adhesion properties, while aluminum powder paint serves as a durable topcoat. This method protects pipelines from environmental factors but doesn't address internal corrosion. Combining external coating with internal corrosion treatment ensures comprehensive protection.
Anti-corrosion of Oil Storage Tanks
1. Internal Anti-corrosion in Oil Storage Tanks
In the anti-corrosion process of oil storage tanks, safeguarding against corrosion within the tank is paramount. Operational practices involve allocating specific storage tanks based on the type of crude oil, such as gasoline or diesel oil, with variations in anti-corrosion treatments for roof tanks and floating roof tanks. The in-tank anti-corrosion process holds utmost significance, considering it is the direct contact point for petroleum liquid. Various anti-corrosion technologies are applied based on the specific areas within the tank experiencing contact. Gas corrosion, primarily from acidic gases like carbon dioxide or water vapor introduced during petroleum input, poses a significant threat to the top of oil tanks. This gas-induced corrosion, termed oxygen depolarization reaction, can be more severe than direct contact corrosion. During oil transportation, instability in the tank can lead to collisions and shaking, resulting in increased volatile gas in the oil and intensified corrosion, surpassing that of gas corrosion alone. Apart from areas not directly in contact with oil, such as the tank top, positions like the tank wall and tank bottom experience corresponding corrosion due to direct contact with oil. The tank wall undergoes chemical property changes over time, while the tank bottom faces complex corrosion factors, including water molecule accumulation and impurity buildup in the oil, leading to both chemical and electrochemical corrosion. Coating anti-corrosion technology, with materials like epoxy coatings known for acid and alkali corrosion resistance, is widely employed. Additionally, cathodic protection technology can be used to electrify and prevent corrosion. In the design stage of storage tank development, attention should be given to parts prone to corrosion, reinforcing them through measures like increased metal thickness to prolong the tank's service life. Regular maintenance inspections during tank use are crucial to monitor corrosion reduction, economic losses, and potential accidents.
2. External Anti-corrosion of Storage Tanks
Tank anti-corrosion encompasses both in-tank and external-tank protection. External tank corrosion primarily stems from atmospheric factors, known as atmospheric corrosion. The degree of corrosion on the tank wall's outer surface is closely tied to the regional climate, environment, and air quality. Coastal cities in China, for instance, face higher humidity, industrial development, and air pollution, leading to increased atmospheric corrosion. To counter this, materials for external tank coatings should be selected based on factors such as waterproofing, grease, and acid-resistant epoxy coatings. Enhancing oil quality involves minimizing corrosive additives during storage, selecting corrosion-resistant materials, and addressing wear resistance to prevent issues like cracking due to pitting corrosion and stress corrosion in stainless steel materials.
Conclusion
As one of the vital strategic resources driving the advancement of petroleum industrialization, the transportation and storage of oil pipelines bear immense significance for national economic development and security. Ensuring the safety of strategic oil storage tasks is crucial to meet the requirements of national economic progress. To mitigate the corrosion of oil pipelines and storage tanks, it becomes imperative to adopt suitable protective measures tailored to the specific circumstances. Furthermore, enhancing the quality of the oil itself and employing materials with robust anti-corrosion properties in the fabrication of pipes and storage tanks are essential measures in the realm of energy management.
