For a long time, corrosion has been one of the more serious problems in chemical equipment, ranging from damage to equipment to accidents and even disasters. According to statistics, about 60% of the damage of chemical equipment is caused by corrosion, so in the selection of chemical valves, we should first pay attention to scientific selection. Here are some of the most commonly used chemical media to discuss the key points of selection:

1。 Sulfuric acid is a strong corrosive medium, and sulfuric acid is an important industrial material with a wide range of applications. For concentrated sulfuric acid, carbon steel and cast iron with a concentration of more than 80% and a temperature of less than 80 °C, it has good corrosion resistance, but it is not suitable for high-speed flow of sulfuric acid, and is not suitable for pump and valve materials; Ordinary stainless steels such as 304 (0CR18NI9), 316 (0Cr18Ni12Mo2Ti) are also limited in their use for sulfuric acid media. Therefore, pumps and valves for transporting sulfuric acid are usually made of high-silicon cast iron (difficult to cast and machine) and high-alloy stainless steel (alloy 20). Fluoroplastics have good resistance to sulfuric acid, and fluorine-lined valves are a more economical option.

2。 Acetic acid is one of the corrosive substances in organic acids, ordinary steel will be severely corroded at all concentrations and acetic acid temperatures, stainless steel is a good acetic acid resistance, molybdenum-containing 316 stainless steel can also be used to dilute acetic acid vapor at high temperatures. High temperature and high concentration acetic acid or other corrosive media, such as harsh requirements, can choose high-alloy stainless steel valves or fluoroplastic valves.

3。 Most metal materials with hydrochloric acid are not resistant to hydrochloric acid corrosion (including stainless steel materials), and molybdenum-containing ferrosilicon can only be used for hydrochloric acid at 50°C with a concentration of less than 30%. Contrary to metallic materials, most non-metallic materials have good corrosion resistance to hydrochloric acid, so glue-lined valves and plastic valves (such as polypropylene, fluoroplastics, etc.) are ideal for conveying hydrochloric acid.

4。 Nitric acid is generally corroded and destroyed in the metal in nitric acid, stainless steel is the more commonly used nitric acid resistant material, nitric acid has good corrosion resistance at room temperature, it is worth mentioning that molybdenum-containing stainless steel (such as 316, 316L) corrosion-resistant nitric acid is not better than ordinary stainless steel (such as 304, 321), sometimes even worse. For high-temperature nitric acid, titanium and titanium alloy materials are commonly used.

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

2。醋酸是有机酸中具有腐蚀性的物质之一, 普通钢在所有浓度和醋酸温度下都会受到严重腐蚀, 不锈钢是一种良好的耐醋酸、含钼316不锈钢也可用于高温稀释醋酸蒸汽。高温高浓度醋酸或其他腐蚀性介质, 如苛刻要求, 可选用高合金不锈钢阀门或氟塑料阀门。
3。盐酸大部分金属材料都不耐盐酸腐蚀 (包括不锈钢材料), 含钼高硅铁只能用于50℃, 浓度不到30%的盐酸。与金属材料相反, 绝大多数非金属材料对盐酸具有良好的耐腐蚀性, 因此衬胶阀和塑料阀门 (如聚丙烯、氟塑料等) 是输送盐酸的理想选择。
4。硝酸一般在硝酸中的金属被腐蚀和破坏, 不锈钢是较常使用的耐硝酸材料, 硝酸在室温下具有良好的耐腐蚀性, 值得一提的是,含钼不锈钢 (如316、316L) 耐腐蚀的硝酸不比普通不锈钢好 (如304、321), 有时甚至更糟。对于高温硝酸, 通常使用钛和钛合金材料。
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