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Alloy 400 (Monel 400)


•ALLOY400 is a single-phase solid-solution Ni-Cu alloy with excellent corrosion resistance to a wide range of media.
•corrosion resistance in a wide range of marine and chemical environments
•freedom from chloride induced stress-corrosion cracking
•good mechanical properties from sub-zero temperatures up to about 550 ‹C (1020 ‹F)
•approved for pressure vessels with wall temperatures from -10 to 425 ‹C (14 to 800 ‹F) according to VdTUV-Wbl. 263 and up to 900 ‹F (480 ‹C) according to ASME Boiler and Pressure Vessel Code.
•good workability and weldability

Corrosion resistance

ALLOY400 has outstanding resistance to neutral and alkaline salt solutions. It has been a standard material for salt plants for many years. This alloy is one of the few metallic materials which can be used in contact with fluorine, hydrofluoric acid, hydrogen fluoride or their derivatives. ALLOY400 shows very high resistance to caustic alkalies. Behaviour in seawater is also excellent, with improved resistance to cavitation corrosion compared with copper-base alloys. It can be used in contact with dilute solutions of mineral acids such as sulphuric and hydrochloric acids, particularly if they are air-free. However, as the alloy contains no chromium, corrosion rates may increase significantly under oxidizing conditions. Whilst ALLOY400 can be considered immune to chlorideion stress cracking, it can stress crack in the presence of mercury or in moist aerated HF vapours. A stressrelieving heat treatment is applied in such cases.


•Typical applications are:
•feed-water and steam generator tubing in power plants
•brine heaters and evaporator bodies in seawater desalination plants
•sulphuric and hydrofluoric acid alkylation plants
•sulphuric and hydrofluoric acid alkylation plants
•cladding for crude oil distillation columns
•splash-zone sheathing in offshore structures
•propeller and pump shafts for seawater service
•plants for uranium refining and isotope separation in the production of nuclear fuel
•pumps and valves used in the manufacture of chlorinated hydrocarbons
•monoethanolamine (MEA) reboiler tubes
•valves and heat exchangers exposed to oxygen at higher temperatures, pressure and concentration of oxygen to avoid combustion and ignition through oxygen
•sour gas environment: Nicorros is listed in NACE Standard MR0175 ("Sulfide Stress Cracking Resistant Metallic
Materials for Oilfield Equipment") as acceptable up to a maximum hardness value of 35 HRC