Introduce the causes of corrosion in oil and gas pipelines
Thread Content
Corrosion refers to the chemical and electrochemical reactions between the surface of a metal material and the environmental medium, which lead to the degradation and destruction of the material. The common corrosion in oil and gas pipelines is caused by corrosive substances such as CO2, H2S, C1– dissolved in crude oil, a small amount of dissolved oxygen, and bacteria; these substances react directly with the metal, leading to chemical corrosion. Chemical corrosion is not very harmful, while the main cause of bulges on the surface of steel pipes, leading to perforations, is electrochemical corrosion. When a metal undergoes an electrochemical reaction, the area with a lower electrode potential tends to lose electrons and becomes the anode ； The area with a higher electrode potential receives electrons and becomes the cathode. In the presence of O2 and H2O, Fe(OH)2 transforms into hydrated iron oxide, thereby causing corrosion.
The corrosion of oil and gas pipelines is mainly caused by corrosive substances in crude oil such as CO2, H2S, Cl-, dissolved oxygen, and bacteria. These substances undergo chemical reactions directly with metals, causing chemical corrosion. In contrast, electrochemical corrosion is more severe; it occurs when the anodic area on the metal surface loses electrons while the cathodic area gains them. Especially in the presence of O2 and H2O, hydrated iron oxide is formed, leading to further corrosion and damage of the pipes. .