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Alloy 22

Alloy 22, Alloy C-22, UNS N06022, W.Nr. 2.4602

Alloy 22 is a fully austenitic advanced corrosion-resistant alloy that offers resistance to both aqueous corrosion and attack at elevated temperatures. This alloy provides exceptional resistance to general corrosion, pitting, crevice corrosion, intergranular attack, and stress corrosion cracking.

Alloy 22 is nickel-base and typically contains 22% chromium, 14% molybdenum, 3% tungsten and extremely low carbon and silicon content. Iron is normally limited to less than 3%. The alloy’s high content of chromium gives it good resistance to wet corrosion by oxidizing media (e.g., nitric acid and ferric and cupric salts). Its contents of molybdenum and tungsten give the alloy resistance to wet reducing media (e.g., sulfuric and hydrochloric acids). Alloy 22 exhibits excellent resistance to corrosive attack by seawater under stagnant and flowing conditions.

Alloy 22 is characterized by Extraordinary resistance across a wide range of corrosive media under oxidizing and reducing conditions, particularly high resistance to crevice, pitting, and stress corrosion.

Alloy 22 has a broad field of application in the chemicals and petrochemicals industry and is used for components in organic processes that contain chloride and for catalytic systems. The material is especially effective in hot, contami- nated mineral acids, solutions, organic acids (such as formic acid and acetic acid) or sea water. Other fields of application are:

Acetic acid production

Pharmaceuticals industry

Fine chemicals

Alloy 22 tube and pipe shall be furnished in the solution annealed and descaled condition.

Due to the extremely low carbon and silicon concentrations, Alloy 22 has no propensity for grain boundary disper- sions in hot forming or welding. This alloy can therefore be used in many chemical processes with both oxidizing and reducing media when welded. The high chrome, molybdenum, and nickel concentrations make the alloy resistant to chlo- ride ion attacks. The tungsten concentration further increases this resistance. Alloy 22 is resistant to chlorine gas, hypochlorite, and chlorine dioxide solutions such as those that can be encountered in the cellulose industry. The alloy is characterized by excellent resistance to concentrated solutions of oxidizing salts (such as iron III and copper chloride).

(1) Hot formed, annealed, descaled

(2) Cold worked and bright annealed

(3) Cold worked, bright annealed, polished (MP, EP, CP etc.)

Chemical composition

Tension

Hardness

Flaring

Flange

Flattening

Micro structure

Hydrostatic

NDT

Intergranular Corrosion

Surface condition

Shape and dimension

Positive Material Identification