825 - Print

CHEMICAL COMPOSITION %

DESCRIPTION

Alloy 825 is a Nickel-iron-chromium alloy with additions of molybdenum, copper and titanium. The alloy chemical composition provides exceptional resistance to many corrosive environments. The Nickel content is sufficient for resistance Chloride-ion stress corrosion cracking. The Nickel, combined with molybdenium and copper, also gives outstanding resistance to reducing environments such as those containing sulfuric and phosphoric acid. The molybdenium also aids resistance to pitting and crevice corrosion. The alloy Chromium content confers resistance to a variety of oxidizing substances such as nitric acid, nitrates and oxidizing salts. The titanium addition, with appropriate heat treatment, will stabilize the alloy against sensitization to intergranular corrosion.

DESIGN FEATURES

• Good resistance to stress corrosion
• Satisfactory resistance to pitting and crevice corrosion
• Good resistance to oxidizing and non-oxidizing hot acids
• Good mechanical properties at both room and elevated temperatures up to approximately 550° C (1020° F)
• Permission for pressure-vessel use at wall temperatures up to 425° C (800° F)

TYPICAL APPLICATIONS

Components such as heating coils, tanks, crates, baskets and chains in sulfuric acid pickling plants. Fuel element dissolvers where the alloy withstands different media (sulfuric and nitric acids, caustic hydroxide, etc.) used in processing. Sea water cooled heat exchangers; offshore product piping system tubes and components in sour gas service – resistant to chloride-ion stress-corrosion cracking. Pipelines carrying wet sulphur dioxide gas and pulp digesters in the papermaking process. Heat exchangers, evaporators, scrubbers, etc. used in phosphoric acid production. Air cooled heat exchangers used in the processing of liquid petroleum gas (LPG).

GENERAL MECHANICAL REQUIREMENTS

KSI can be converted to MPA (Megapascals) by multiplying by 6.895.