Monel alloys, cast nickel alloys, Hastelloy, etc. are all materials used to manufacture special purpose valves. Nickel Alloy: Also known as Monel alloy, it is an alloy made of metal nickel as a matrix by adding copper, iron, manganese and other elements. Monel is a high nickel-copper alloy with good corrosion resistance. Monel alloy is a Ni-Cu alloy in nickel-based corrosion-resistant alloys. It was first developed by International Nickel Company (International Nickel Company) in the United States. Its typical composition is 70% Ni and 30% Cu. It is a nickel-based corrosion-resistant alloy. the most widely used alloy. Monel alloy has good corrosion resistance and is silvery white, which is suitable for edge wire material. This material is often used in valves conveying alkalis, salt solutions, foods, and many airless acids, especially sulfuric and hydrofluoric acids. Monel valves are ideal for steam, seawater and marine environments.
Monel alloy not only has high strength and toughness, but also has excellent corrosion resistance to reducing acid and strong alkali medium and seawater. Therefore, it is usually used to manufacture equipment for conveying hydrofluoric acid (HF), brine, neutral medium, alkali salt and reducing acid medium C23. Monel alloy is also suitable for drying chlorine gas, hydrogen chloride gas, high temperature chlorine gas (425℃) and high temperature hydrogen chloride (450℃) and other media, but it is not resistant to the corrosion of sulfur-containing media and oxidizing media (such as nitric acid, media with high oxygen content) , because nickel reacts violently with sulfur and oxygen, it is easy to form Ni3S2 and NiO.
Uses of Monel
The structure of Monel 400 alloy is a high-strength single-phase solid solution, which is a corrosion-resistant alloy with the largest dosage, the most extensive use and excellent comprehensive properties. Monel alloy has excellent corrosion resistance in hydrofluoric acid and fluorine gas medium, and also has excellent corrosion resistance in hot concentrated lye. At the same time, it is also resistant to corrosion by neutral solutions, water, seawater, atmosphere, organic compounds, etc. An important feature of Monel alloy is that it generally does not produce stress corrosion cracking and has good cutting performance.
Monel K500 (K500, NCu30-2-1, UNS N05500) alloy not only has excellent mechanical properties such as high strength, corrosion resistance and non-magnetic properties, but also has the same corrosion resistance as Monel 400. It can be used as a pump shaft material and is suitable for working under the harsh geological mining conditions of high-sulfur and high-wax oil layers. Since Monel has no plastic-brittle transition temperature, it is very suitable for various low temperature equipment. This alloy is mainly used for pump shafts and valve stems, conveyor scrapers, oil well drill collars, elastic parts, valve pads, etc. It is suitable for petroleum, chemical shipbuilding, pharmaceutical and electronic sectors.
Corrosion resistance of Monel alloy
Monel alloy has excellent corrosion resistance in fluorine gas, hydrochloric acid, sulfuric acid, hydrofluoric acid and their derivatives. Acid medium: M400 is resistant to corrosion in sulfuric acid with a concentration of less than 85%. M400 is one of the few important materials that is resistant to hydrofluoric acid. Water corrosion: M400 alloy not only has excellent corrosion resistance in most water corrosion conditions, but also pitting corrosion and stress corrosion are rarely found. Generally around 600℃, in high temperature steam, the corrosion rate is less than 0.026mm/a. Ammonia: Due to the high nickel content of Monel 400 alloy, it is resistant to corrosion under anhydrous ammonia and ammoniated conditions below 585°C.