Material selection for sulfuric acid transfer pumps

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Sulfuric acid is an important industrial raw material with a wide range of applications. It is also one of the most corrosive substances; like all strong acids, it contains a large number of hydrogen ions, making it an effective cathodic depolarizer. The electrode potential of most industrial metals and alloys is lower than that of the hydrogen electrode, so they dissolve rapidly when exposed to sulfuric acid solutions. There is also a significant difference in the corrosivity of dilute sulfuric acid and concentrated sulfuric acid; dilute sulfuric acid generally only has acidic properties, while concentrated sulfuric acid not only has acidic properties but is also a strong oxidizing agent. Therefore, concentrated sulfuric acid has both hydrogen depolarization and oxygen depolarization effects. Some materials resistant to dilute sulfuric acid will corrode rapidly in concentrated sulfuric acid, and the presence of air or other oxidizing agents in dilute sulfuric acid also increases its corrosiveness. There are also some metals and alloys that are not resistant to dilute sulfuric acid but can be easily passivated; they are able to form a protective layer in concentrated sulfuric acid, thereby gaining resistance to it (such as cast iron). \ Having introduced the properties of sulfuric acid, what material should be used for sulfuric acid transfer pumps? Firstly, iron and steel have good resistance to concentrated sulfuric acid, but they are not suitable for dilute sulfuric acid with a concentration of 70–80% or less. The higher the concentration, the better the resistance of steel and iron. For fuming sulfuric acid with a concentration of over 100%, cast iron cannot be used, while carbon steel can be used for fuming sulfuric acid with a concentration of over 102%. The metals and alloys that can resist both concentrated sulfuric acid and dilute sulfuric acid include only high-silicon iron, highly alloyed stainless steels, nickel-molybdenum and nickel-molybdenum-chromium alloys, gold, platinum, barium, etc. Except for high-silicon ferroalloy, the above materials are all expensive, so they are not suitable as materials for sulfuric acid transfer pumps. High-silicon iron can withstand sulfuric acid of all concentrations at high temperatures and high speeds, but it has a serious drawback: its resistance to vibration and mechanical shock is poor, and it is also difficult to process, which limits its applications. Therefore, as a sulfuric acid transfer pump, non-metallic materials are generally chosen. The editor recommends fluorine-lined or fluoroplastic pumps for this purpose; they can be used for sulfuric acid of any concentration at temperatures below 150°C. For temperatures above 110°C, it is necessary to contact Anhui Xinfu Pump Valve Company in order to select a high-temperature resistant sulfuric acid transfer pump. Among non-metallic materials, commonly used acid-resistant silicate materials such as ceramics, glass, acid-resistant enamel, and acid-resistant rocks can withstand sulfuric acid at various concentrations and temperatures, and are widely used for lining tanks, towers, and various small standalone devices. \ Sulfuric acid transfer pumps are widely used, as sulfuric acid is one of the most produced chemicals in the chemical industry and one of the most important commodities in the national economy. Almost all industries use sulfuric acid directly or indirectly, including those involved in fertilizers, dyes, pigments, pharmaceuticals, hydrochloric acid and other chemicals, detergents, synthetic fibers, oil refining, acid cleaning of steel and other metals, metal purification, rubber production, and battery manufacturing. Original address: Anhui Xinfu Pump Valve Technology Co., Ltd. www.ahxfbf.com http:www.ahxfbf.com