For a long time, corrosion has been one of the more serious problems in chemical equipment. At the very least, the equipment is damaged, and at the worst, it can lead to accidents and even disasters. According to statistics, about 60% of the damage to chemical equipment is caused by corrosion, so when selecting chemical valves, we must first pay attention to scientific choices. The following are some commonly used chemical media to discuss the key points of selection:

1. Sulfuric acid is a highly corrosive medium, and sulfuric acid is an important industrial material and has a wide range of applications. The corrosion of sulfuric acid at different concentrations and temperatures varies from material to material. Concentrated sulfuric acid, carbon steel and cast iron with concentrations exceeding 80% and temperatures less than 80℃ have good corrosion resistance, but it is not suitable for high-speed flowing sulfuric acid and is not suitable as pump and valve materials; ordinary stainless steels such as 304 (0CR18NI9) and 316 (0Cr18Ni12Mo2Ti) are also limited in their use in sulfuric acid media. Therefore, pumps and valves that convey sulfuric acid are usually made of high silicon cast iron (casing and processing difficult), high alloy stainless steel (20 alloy). Fluoroplastics have good sulfuric acid resistance, and using fluorine-lined valves is a relatively economical choice.

2. Acetic acid is one of the corrosive substances among organic acids. Ordinary steel will be severely corroded at all concentrations and acetic acid temperatures. Stainless steel is a good acetic acid-resistant, molybdenum-containing 316 stainless steel can also be used to dilute acetic acid steam at high temperature. High temperature and high concentration acetic acid or other corrosive media, if required, high alloy stainless steel valves or fluoroplastic valves can be used.

3. Most metal materials of hydrochloric acid are not resistant to hydrochloric acid corrosion (including stainless steel materials). Molybdenum-containing high ferrosilicon can only be used for hydrochloric acid at 50℃ and concentrations less than 30%. In contrast to metal materials, most non-metallic materials have good corrosion resistance to hydrochloric acid, so lining valves and plastic valves (such as polypropylene, fluoroplastic, etc.) are ideal choices for transporting hydrochloric acid.

4. Nitric acid is generally corroded and destroyed in nitric acid. Stainless steel is a relatively commonly used nitric acid-resistant material. Nitric acid has good corrosion resistance at room temperature. It is worth mentioning that nitric acid that is resistant to corrosion by molybdenum-containing stainless steel (such as 316, 316L) is no better than ordinary stainless steel (such as 304, 321), and sometimes even worse. For high temperature nitric acid, titanium and titanium alloy materials are usually used.

How to choose the material of chemical valves? Through the above introduction, you should know how to choose the material of chemical valves!