A brief discussion on the corrosion problem in industrial waste pipes

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A brief discussion on corrosion in industrial wastewater pipelines: The composition of the media transported through these pipelines is complex, and the acidic or alkaline substances present in the wastewater can cause corrosion to the pipelines； As the retention time of wastewater in the pipes increases, the dissolved oxygen and nitrates in the wastewater are completely consumed; the anaerobic environment within the pipes promotes the formation of hydrogen sulfide gas, and H2S causes corrosion to the pipes ； The S in wastewater is converted into H2SO4 through a series of biochemical reactions, which then reacts with the cement-based materials in the pipes, causing corrosion of those pipes. Furthermore, for pipelines that transport certain special fluids, such as oil field production water, methanol needs to be injected into the gas collection pipelines at the wellhead during gas field exploitation in order to prevent the formation of natural gas hydrates. This results in the creation of alcohol-containing wastewater in the gas field, and such wastewater accelerates pipeline corrosion. Factors such as pH, dissolved oxygen, dissolved salts, CO2, H2S, bacteria, as well as changes in pressure and temperature in oily wastewater, are all causes of corrosion in pipelines. When CO2 and H2S dissolve in water, they form acids that cause corrosion of steel. Additionally, since O2 is a depolarizing agent, the O2 dissolved in water can exacerbate the corrosion of metal pipe walls caused by CO2 and H2S. Some microbial bacteria (such as iron bacteria) can obtain energy for their metabolism in neutral media by altering the valence state of iron ions. The ferric ions produced as a result of these reactions possess strong oxidizing properties, which enable them to oxidize sulfides into sulfuric acid, thereby causing corrosion of pipes.