Nickel tube fittings in the nickel insoluble in water, normal temperature in the humid air surface formation of a dense oxidation film, can prevent the block metal further oxidation.

In dilute acids, it dissolves slowly, releasing hydrogen to produce green nickel ions Ni 2+, which burns in pure oxygen and gives off a bright white light. Similarly, nickel can be burned in chlorine and fluorine without reacting to a solution of oxidizer containing nitric acid.

The nickel in the nickel pipe fittings is a reducing agent of medium strength. The corrosion of nickel by nickel, hydrochloric acid, sulfuric acid and alkaline solution is very slow. Nickel dissolves slowly in dilute nitric acid. Nickel, such as platinum and palladium, absorbs large amounts of hydrogen during passivation, and the smaller the particle size, the larger the absorption.

The important salts of nickel pipe fittings are nickel sulfate and nickel chloride. Nickel nitrate is also commonly used in laboratory crystallization water. Its chemical formula is ni (NO3) 2.6h2o. Similar to iron and cobalt, nickel crucible can be used for laboratory molten alkali, as it is stable to water and air at room temperature and resistant to alkaline corrosion. Nickel sulfate (NISO4) can form alum Ni (SO4) 2O6H2O (Mi is alkali metal ion) with alkali metal sulfate. The +2 valence nickel ions can form coordination compounds.

At constant pressure, nickel in nickel pipe fittings reacts with carbon monoxide to form harmful nickel tetracharbonyl (ni (co) 4, which is then heated and decomposed into nickel and carbon monoxide.

Nickel is mostly used in petrochemical industry, aerospace, Marine equipment, nuclear industry and other fields. Its resistance to alkali corrosion is only inferior to that of silver in metallic materials. Nickel and nickel-copper alloys form a black protective film on the surface of concentrated alkali, making them resistant to corrosion.

Therefore, nickel-copper alloy in nickel-pipe fitting is particularly suitable for the production and treatment of concentrated alkali liquid equipment. The main factors affecting the service life of nickel equipment are the concentration of caustic soda, temperature and impurity content, especially the content of sodium chloride and sodium chloride. The higher the concentration of caustic soda, the lower the impurity content, the longer the service life. In recent years, nickel and nickel-copper alloys have played an important role in the chlor-alkali industry.