Description
INCONEL Alloy C-276
For over fifty years INCONEL® alloy C-276 has been associated with outstanding corrosion resistance in both acid and alkali media. The Nickel-Chromium-Molybdenum superalloy combined with a controlled amount of Tungsten has made this the material of choice for severe corrosive environments. The low carbon content minimises the carbide precipitation during heat treatment and during welding. As a result in as-welded structures, the excellent pitting and crevice corrosion resistance is maintained. The welding consumable is often overmatched with lower alloyed materials to provide security in the weld zone.
The alloy has been successfully adopted in chemical processes containing ferric and cupric chloride ions, chlorine, hypochlorite, chlorine dioxide, organic acids, acetic anhydride, seawater, brine and sour oil and gas wellhead fluids.
Applications for the alloy include power station flue gas desulphurisation components like ducts and fans, louvers and gas valves, dampers, scrubbers, chimney stack linings and containment housings. In chemical, pharmaceutical and food processing the mixing vessels and reaction chambers together with heat exchangers and transfer piping, valves and pumps have been manufactured in INCONEL® alloy C-276. Aggressive environments in the pulp and paper and waste fluid treatment plants will use INCONEL® alloy C-276 as a result of the overall corrosion resistance provided by the alloy in the most aggressive sections of the system.
Corrosion Resistance
INCONEL® alloy C-276 is resistant to general corrosion, stresscorrosion cracking, pitting and crevice corrosion in a broad range of severe environments. Its resistance to carbide precipitation during welding maintains corrosion resistance in the heat-affected zones of welded joints. It has exceptional resistance to sulphuric acid and hydrochloric acid. It resists many of the most severe media encountered in chemical processing, including reducing and oxidising acids, highly oxidising neutral, and acid chlorides, solvents, formic and acetic acids, acetic anhydride, wet chlorine gas, hypochlorites, and chlorine solutions. It has excellent resistance to phosphoric acid.
At all temperatures below the boiling point and at concentrations lower than 65 wt %, tests have shown corrosion rates of less than 5 mpy (0.13 mm/y). INCONEL® alloy C-276 exhibits excellent resistance to corrosion by seawater, especially under crevice conditions which induce attack in other commonly used materials.
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