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Alloy200/201

Alloy 200/201 (Nickel 200/201)

Characteristics

ALLOY200/201 is an unalloyed wrought nickel which have excellent resistance to many corrosive media from acid to alkaline.

•excellent corrosion resistance in many alkaline media
•good mechanical properties within a wide range of temperatures
•magnetization decreasing continuously between -273 and 360 ‹C (-458 and 680 ‹F) and showing paramagnetism

Corrosion resistance

Alloy 200 and Alloy 201 have excellent resistance to many corrosive media from acid to alkaline. They are most useful under reducing conditions but, where a passive oxide is formed, they may also be used in oxidizing conditions. Their most significant property is extremely high resistance to caustic alkalies up to and including the molten state. The extra-low carbon content of Alloy 201 gives virtual mmunity to intergranular attack above about 315 ‹C ( 600 ‹F). The presence of chlorates must be kept to a minimum, as they accelerate the rate of attack. The resistance of Alloy 200 and Alloy 201 to mineral acids varies according to temperature and concentration and whether or not the solution is aerated. Corrosion resistance is better in deaerated acid. In acid, alkaline and neutral salt solutions, Alloy 200 and Alloy 201 show good resistance, but severe attack occurs in oxidizing salt solutions. Both alloys are resistant to all dry gases at room temperature. The low-carbon alloy can be used in dry chlorine and hydrogen chloride ? at temperatures up to 550 ‹C (1020 ‹F)

Applications

Unalloyed wrought nickel combines excellent mechanical properties with good corrosion resistance. Above 300 ‹C (570 ‹F) working temperature, the low-carbon version is generally used. The limited carbon content lowers mechanical property values and work-hardening rate but promotes ductility.

Typical applications are:

•food production, such as handling of cooling brines, fatty acids and fruit juices ? resistance to acid, alkaline and neutral salt solutions and to organic acids.
•vessels in which fluorine is generated and reacted with hydrocarbons ? resistance to fluorine
•storing and transportation of phenol ? immunity from any form of attack ensures absolute product purity
•manufacture and handling of sodium hydroxide, particularly at temperatures above 300 ‹C (570 ‹F).

Industrial processes where sodium hydroxide is typically used, involve:

•production of hydrochloric acid and chlorination of hydrocarbons such as benzene, methane and ethane ? resistance at elevated temperatures to dry chlorine and hydrogen chloride
•manufacture of vinyl chloride monomer ? resistance to hydrogen chloride at elevated temperatures