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For a long time, corrosion has been one of the serious problems in chemical processing equipment; it can cause damage to the equipment at the least, and in more severe cases, it can lead to accidents or even disasters. According to statistics, about 60% of damage to chemical equipment is caused by corrosion; therefore, when selecting chemical industry valves, it is important to make a scientific choice first. The following are key points for discussing the selection of common chemical media: 1. Sulfuric acid is a highly corrosive substance; it is also an important industrial material with wide-ranging applications. Sulfuric acid at different concentrations and temperatures causes varying degrees of corrosion to materials. For concentrated sulfuric acid with a concentration above 80% and a temperature below 80°C, carbon steel and cast iron exhibit good corrosion resistance; however, it is not suitable for sulfuric acid that flows at high speeds, and thus cannot be used as material for pumps and valves. Ordinary stainless steels such as 304 (0CR18NI9) and 316 (0Cr18Ni12Mo2Ti) also have limited performance when exposed to sulfuric acid. Therefore, the pumps and valves used for transporting sulfuric acid are usually made of high-silicon cast iron (which is difficult to cast and machine) or highly alloyed stainless steel (Grade 20 alloy). Fluoroplastics have good resistance to sulfuric acid, making the use of fluorinated-lined valves a cost-effective option. 2. Acetic acid is one of the corrosive organic acids; ordinary steel suffers severe corrosion at all concentrations and temperatures involving acetic acid. Stainless steel offers good resistance to acetic acid, and 316 stainless steel containing molybdenum can also be used for handling acetic acid vapor at high temperatures. For high temperatures and high concentrations of acetic acid or other corrosive media, or in cases where stringent requirements apply, high-alloy stainless steel valves or fluoroplastic valves can be used. 3. Most metal materials are not resistant to corrosion by hydrochloric acid (including stainless steel); ferrosilicon with high molybdenum content can only be used in hydrochloric acid at 50°C and with a concentration of less than 30%. Unlike metal materials, the vast majority of non-metallic materials exhibit good corrosion resistance to hydrochloric acid; therefore, rubber-lined valves and plastic valves (such as polypropylene, fluoroplastics, etc.) are ideal choices for transporting hydrochloric acid. 4. In nitric acid, metals generally get corroded and damaged. Stainless steel is a commonly used material resistant to nitric acid; it exhibits good corrosion resistance at room temperature. It is worth noting that molybdenum-containing stainless steels (such as 316 and 316L) do not have better corrosion resistance to nitric acid than ordinary stainless steels (such as 304 and 321), and in some cases their resistance is even worse. For high-temperature nitric acid, titanium and titanium alloy materials are commonly used. How should the material for chemical industry valves be chosen? Through the above introduction, everyone should now know how to choose the material for chemical industry valves!