Incoloy Alloy 825 Seamless Nickel Alloy Pipe BS 3074NA16 ASTM B 163 ASTM B 423

Incoloy alloy 825 is a nickel-iron-chromium alloy with additions of copper, molybdenum and titanium. The alloy's chemical composition is designed to provide exceptional resistance to many corrosive environments. The nickel content is sufficient for resistance to chloride-ion stress corrosion cracking. The nickel, in conjunction with the molybdenum and copper, also gives outstanding resistance to reducing environments such as those containing sulfuric and phosphoric acids. The molybdenum also aids resistance to pitting and crevice corrosion. The alloy's chromium content confers resistance to a variety of oxidizing substances such as nitrates, nitric acid and oxidizing salts. The titanium addition serves, with an appropriate heat treatment, to stabilize the alloy against sensitization to intergranular corrosion. The resistance of Incoloy 825 to general and localized corrosion under diverse conditions gives the alloy broad usefulness. Applications include chemical processing, pollution control, oil and gas recovery, acid production, pickling operations, nuclear fuel reprocessing and handling of radioactive wastes.

.The outstanding property of Incoloy 825 is its corrosion resistance. In reducing & oxidising conditions, Incoloy 825 resists general corrosion, pitting & crevice corrosion, intergranular corrosion and stress corrosion cracking. It is particularly useful in sulphuric & phosphoric acids, sulphur containing flue gases, sour gas and oil wells and sea water.

Incoloy 825 is approved for pressure vessel operating temperatures up to 525C (AS1210, AS4041), 538C (ASME Boiler & Pressure Vessel Code, Sections I, III, VIII, IX, Cases 1936, N-188). Brittle phases may form in alloy 825 at temperatures above ~ 540C, so it is not normally used at these temperatures, where creep-rupture properties would be design factors.

Chemical Composition of Incoloy Alloy 825

Table 1. Chemical composition of Incoloy Alloy 825 (ASTM B163  Heat exchanger tube)