Metal selection for hydrofluoric acid
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What metal materials are resistant to hydrofluoric acid? Ordinary materials will be corroded when hydrogen fluoride is present in aqueous form. Which materials have better corrosion resistance? Monel, Inconel, Hastelloy……How should one choose a material? Applicable conditions?
Reply to 2# hatawoo: What type of pump is generally used to transport hydrofluoric acid? Are there diaphragms for diaphragm pumps made of Monel?
Monel alloy exhibits excellent corrosion resistance in fluorine gas, hydrochloric acid, sulfuric acid, hydrofluoric acid, and their derivatives. Acidic medium: M400 is corrosion-resistant in sulfuric acid with a concentration of less than 85%. The M400 is one of the very few important materials resistant to hydrofluoric acid. Water corrosion: In most cases of water corrosion, the M400 alloy exhibits excellent corrosion resistance; pitting and stress corrosion are also rare occurrences, with a corrosion rate of less than 0.025 mm/year. High-temperature corrosion: The maximum temperature at which M400 can operate continuously in air is around 600°C, and in high-temperature steam, its corrosion rate is less than 0.026 mm/year. Ammonia: Due to its high nickel content, Monel 400 can resist corrosion in anhydrous ammonia and under ammoniated conditions at temperatures below 585°C. The corrosion resistance of Monel K500 in its solid solution state is generally similar to that of Monel 400 alloy; therefore, the corrosion resistance data related to Monel 400 can be applied to Monel K500 alloy as well. Due to its low corrosion rate in flowing seawater and high strength, this alloy is particularly suitable for manufacturing centrifugal pump shafts resistant to seawater corrosion.
Reply to 4# wsm1988: If Monel thin sheets are used as diaphragms for diaphragm pumps, will their mechanical properties be sufficient?
Hastelloy C-2000 is recommended; experiments have shown that its corrosion resistance in both high-temperature HF solutions and HF vapor exceeds that of Monel, especially in gas-phase environments
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Hastelloy is much more expensive than Monel; Monel 400 is the better choice! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !
Hehe, sometimes it’s not about the cost. In gas environments with a concentration of over 60%, the corrosion rate of Monel alloy is so high that it becomes unusable; the corrosion rate of Hastelloy C-2000 is only about 1/5 of that. Additionally, although Monel is cheaper and can be replaced if it gets damaged, maintaining the equipment often means interruptions in production, and the resulting losses are greater compared to the cost of Hastelloy. While increasing the thickness of Monel alloy is one solution, in many cases there are limitations on the size of the components, and overly thick components can sometimes affect the overall performance of the equipment (for example, the heat exchange efficiency of heat exchangers)
Does the use of metal materials require rigidity from the material? Graphite, fluoroplastics, rubber, and including special ceramics can all effectively suppress HF corrosion.
The material with the best corrosion resistance in hydrofluoric acid is platinum; in chemical analysis, experimental equipment lined with platinum is used to handle pressurized hydrofluoric acid at temperatures above 400 degrees, for the decomposition of quartz