INCONEL 690 is a high-chromium nickel alloy having excellent resistance to many corrosive aqueous media and high-temperature atmospheres. The alloy's high chromium content gives it excellent resistance to aqueous corrosion by oxidizing acids (especially nitric acid) and salts, and to sulfidation at high-temperatures. In addition to its corrosion resistance, Inconel 690 has high strength, good metallurgical stability, and favorable fabrication characteristics
Character
The substantial chromium content gives the alloy outstanding resistance to oxidizing chemicals and to high-temperature oxidizing gases.
The high level of nickel imparts resistance to stress-corrosion cracking in chloride-containing environments as well as to sodium hydroxide solutions.
Application
The properties of INCONEL 690 are useful for various applications involving nitric or nitric/hydrofluoric acid solutions. Examples are tail-gas reheaters used in nitric acid production and heating coils and tanks for nitric/hydrofluoric solutions used in pickling of stainless steels and reprocessing of nuclear fuels.
The alloy’s resistance to sulfur-containing gases makes it an attractive material for such applications as coal-gasification units, burners and ducts for processing sulfuric acid, furnaces for petrochemical processing, recuperators, incinerators, and glass vitrification equipment for radioactive waste disposal.
In various types of high-temperature water, Inconel 690 displays low corrosion rates and excellent resistance to stress-corrosion cracking. Thus, the alloy is widely used for steam generator tubes, baffles, tubesheets, and hardware in nuclear power generation.
