Let’s discuss the causes of pipeline corrosion
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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 pipelines is mainly caused by corrosive substances such as CO2, H2S, Cl−, a small amount of dissolved oxygen, and bacteria dissolved in crude oil. These substances interact directly with metals, resulting in 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 forms hydrated iron oxide, thereby causing corrosion.
The main causes of pipeline corrosion are as follows: Firstly, the fluids flowing through the pipelines, such as crude oil, contain corrosive substances such as CO2, H2S, Cl-, along with small amounts of dissolved oxygen and bacteria; these substances can undergo chemical reactions with metals, resulting in chemical corrosion； Secondly, electrochemical reactions occur in the metal within the pipeline; areas with lower electrode potentials tend to act as the anode and lose electrons, resulting in electrochemical corrosion. Furthermore, the presence of oxygen and water in the environment facilitates this process, causing Fe(OH)2 to further convert into hydrated iron oxide and exacerbating the degree of corrosion. .