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Corrosion is undoubtedly the number one hazard that plagues chemical processing equipment. If handled carelessly, it can result in equipment damage at the least, and safety accidents leading to disasters at the worst. Statistics show that approximately 60% of damage to chemical processing equipment is caused by corrosion. However, chemical processing equipment—especially chemical pumps, which are essential for transporting chemical liquids—requires careful consideration regarding material selection during pump specification. When it comes to stainless steel materials, we often have a misconception that they are “all-purpose materials” – that they resist rust and corrosion regardless of the environment or medium, and that they should be used in any operating conditions. In fact, this is very dangerous. As a manufacturer of chemical pumps, at Richter, we frequently encounter requests for transporting various acids and alkalis in the course of our regular customer inquiries. Different chemical media require different materials and pump types. Let’s take a look at the key considerations for selecting pumps for specific chemical media: 1. Sulfuric acid (H2SO4) – Being one of the highly corrosive substances, sulfuric acid is an important industrial material with a wide range of applications. Sulfuric acid at different concentrations and temperatures causes varying degrees of corrosion to materials. For concentrated sulfuric acid with a concentration of over 80% and a temperature below 80°C, carbon steel and cast iron do exhibit good corrosion resistance; however, they are not suitable for use with sulfuric acid that is in high-flow conditions. Due to the flow properties of sulfuric acid, ordinary stainless steels such as 304 (0Cr18Ni9) and 316 (0Cr18Ni12Mo2Ti) also have limited capability for handling sulfuric acid media. Although it is manufactured using high-silicon cast iron (which is difficult to cast and process) and highly alloyed stainless steel (Grade 20 alloy), the processing is challenging and the cost is high; considering these factors of cost and difficulty, it is not a favorable option. Fluoroplastics exhibit excellent resistance to sulfuric acid as well as good corrosion resistance; therefore, using fluoroplastic-lined pumps is a cost-effective option. For dilute acid and sulfate solutions, at room temperature, fluorine-lined magnetic pumps such as RMD, RMI, and IMC; IHF chemical centrifugal pumps; fluorine-lined self-priming magnetic pumps like RMZ and IMZ; and the FZB fluorine-lined self-priming pump series represent a more practical, economical, safe, and cost-effective choice. RMD fluorinated magnetic pump (IMC type). 2. Hydrochloric acid (HCL): The vast majority of metal materials are not resistant to corrosion by hydrochloric acid (including various stainless steel materials); high-molybdenum, high-silicon iron can only be used in hydrochloric acid at temperatures below 50°C and concentrations of 30% or less. However, the vast majority of non-metallic materials exhibit good corrosion resistance to hydrochloric acid. Therefore, fluorine-lined pumps and plastic pumps (such as engineering plastics and fluoroplastics), including RMD, RMI, IMC fluorine-lined magnetic pumps, RMZ, and IMZ fluorine-lined self-priming magnetic pumps, are ideal choices for transporting hydrochloric acid at room temperature. 3. Nitric acid HNO3: For nitric acid, most metals are prone to corrosion, with stainless steel being an exception. It is the most widely used nitric acid-resistant material, possessing excellent corrosion resistance; nitric acid of all concentrations at room temperature has little effect on it. What’s more interesting is that ordinary stainless steels (such as 304 and 321) exhibit better corrosion resistance to nitric acid than molybdenum-containing stainless steels (such as 316 and 316L); therefore, ordinary stainless steel is sufficient for use with nitric acid at room temperature, while fluoroplastic materials are typically used for high-temperature applications involving nitric acid. Dilute nitric acid at room temperature: Stainless steel pumps (RMD, RMI, IMC stainless steel magnetic pumps, insulated magnetic pumps, high-temperature magnetic pumps, IH chemical pump series) are all good choices. High-temperature dilute nitric acid: Fluorine-lined steel pumps (RMD, RMI, IMC fluorine-lined magnetic pumps, RMZ, IMZ fluorine-lined self-priming magnetic pumps, IHF chemical pumps, etc.) are more suitable. 4. Hydrofluoric acid HF: Hydrofluoric acid is one of the highly corrosive substances; it has special properties such as ease of vaporization and toxicity, which imposes higher requirements on the materials used in pump manufacturing as well as on the manufacturing processes. The corrosive effect of hydrofluoric acid on carbon steel and lead is similar to that of sulfuric acid. Among most strong acids, hydrofluoric acid has some unique corrosive properties; however, materials such as tantalum, titanium, and zirconium, which are highly resistant to corrosion in most acids, are not resistant to hydrofluoric acid. All silicon-containing materials cannot be used with hydrofluoric acid. At room temperature, dilute hydrofluoric acid can be used with various plastics; temperature