Monel alloy series valves have excellent resistance to reducing acid media. Especially in high-temperature hydrogen fluoride gas and hydrofluoric acid solution, they have excellent corrosion resistance and are resistant to corrosion of hydrofluoric acid solution of any concentration. They are mainly used in high-temperature hydrogen fluoride gas and hydrofluoric acid solution conditions. At the same time, they are more corrosion-resistant than copper-based alloys in seawater.