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Why do you have to use stainless steel for conveying liquid pipes?

The inner wall of the stainless steel pipe is in direct contact with the conveying liquid. The conveying liquid inside is mixed with many corrosion factors. We know high salinity water, dissolved oxygen, carbon dioxide, hydrogen sulfide, sulfate reducing bacteria and chloride ions. Under the influence of various factors such as temperature and pressure, it has a very serious impact on the local corrosion of stainless steel pipes. Crude oil contains sulfides, naphthenic acids, alkali metal salts and other mesons, which can subject the inner wall of the stainless steel tube to chemical and electrochemical corrosion. Untreated light petroleum products also contain the factors mentioned above, and there are water and oxygen in the oil. SO causes corrosion of the inner wall of the stainless steel pipe when the medium is input into the pipe. In the oil supply and water injection pipelines of the oil field, electrochemical corrosion is often caused on the inner wall of the tube due to the presence of oxygen or sulfate reducing bacteria. The gas pipeline contains moisture such as CO2 and H2S, which causes electrochemical corrosion or stress corrosion cracking.


The corrosion of sulfate-reducing bacteria in steel pipes is the same as that of bacteria in the soil, especially when the pipeline is stopped. Since sulfate-reducing bacteria are present in many soils and waters, it is difficult to prevent them from being carried into tanks and pipelines. The bacteria multiply quickly under suitable conditions, and each cell divides every 20 minutes, so the bacteria can multiply in a short period of time after a period of inactivity (oxygen in a thick-walled stainless steel tube). The bacteria participate in the electrochemical reaction process and generate a large amount of ferrous sulfide. Within a few hours after restarting, the ferrous sulfide can be fused with oxygen to start the oxidation process of the ferrous sulfide, thereby accelerating the corrosion process. As mentioned earlier, the solution is to increase the pH in the medium or add a bactericide to inhibit corrosion.




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