About Alloy
Alloy 28 (UNS N08028, W. Nr. 1.4563) also known as Sanicro 28, is a highly corrosion-resistant alloy belonging to the family of austenitic stainless steels. It is composed of significant amounts of nickel, chromium, and molybdenum, along with smaller additions of copper and nitrogen. This unique combination of elements gives Alloy 28 exceptional resistance to a wide range of corrosive environments, including strong acids, alkalis, and chloride-containing media.
Alloy 28 is particularly well-suited for applications in industries such as chemical processing, power generation, and the oil and gas sector, where exposure to corrosive substances is common. It exhibits excellent resistance to both reducing and oxidizing acids, making it suitable for handling corrosive chemicals like sulfuric acid, phosphoric acid, and nitric acid. Additionally, it has remarkable resistance to stress corrosion cracking, a type of corrosion that occurs under tensile stress in the presence of a corrosive environment, making it ideal for applications involving chloride-rich environments such as seawater systems and acidic chloride solutions.
Apart from its exceptional corrosion resistance, Alloy 28 possesses good mechanical strength, toughness, and weldability. It can withstand elevated temperatures, allowing for high-temperature applications. Common uses for Alloy 28 include chemical processing equipment (tanks, reactors, heat exchangers), flue gas desulfurization systems, offshore oil and gas platforms, pulp and paper industry, and pharmaceutical equipment.
In summary, Alloy 28 is a highly corrosion-resistant alloy that offers excellent resistance to a broad range of corrosive environments. Its composition of nickel, chromium, molybdenum, copper, and nitrogen provides superior resistance to acids, alkalis, and chloride-containing media. With its exceptional corrosion resistance, mechanical properties, and weldability, Alloy 28 is widely used in industries where reliability and resistance to corrosion are critical factors.
Product Form
Seamless Pipe: ASTM B668, ASTM B829
Plate/Strip/Sheet: ASTM B709
Round Bar/Forgings: --
Chemical Composition
| Element | Content (%) |
| Iron, Fe | 29-40.4 |
| Nickel, Ni | 30-34 |
| Chromium, Cr | 26-28 |
| Molybdenum, Mo | 3-4 |
| Manganese, Mn | ≤2.5 |
| Others | Remainder |
Property
| Properties | Metric | Imperial |
| Tensile strength(annealed) | 500 MPa | 72.5 ksi |
| Yield strength(annealed) | 214 MPa | 31 ksi |
| Elongation at Break(Cold worked) | 15% | 50% |
| Modulus of Elasticity | 200 GPa | 29000 ksi |
| Hardness, Rockwell B | 80-90 | 80-90 |
| Hardness, Rockwell C | 33 | 33 |
Application
Chemical Processing Equipment: Alloy 28 is widely used in the manufacturing of chemical processing equipment, including tanks, reactors, heat exchangers, and piping systems. Its resistance to a wide range of corrosive chemicals, such as sulfuric acid, phosphoric acid, and organic acids, makes it an ideal choice for handling corrosive substances.
Flue Gas Desulfurization (FGD) Systems: Alloy 28 is commonly employed in FGD systems, which are designed to remove sulfur dioxide (SO2) emissions from flue gases produced by power plants and industrial processes. Its resistance to corrosive environments containing sulfur compounds, including sulfuric acid, makes it suitable for components such as absorber towers and scrubbers.
Offshore Oil and Gas Platforms: In the oil and gas industry, Alloy 28 finds applications in offshore platforms and facilities. It is used for various components exposed to aggressive seawater environments, such as piping systems, heat exchangers, and valves. Its resistance to chloride-induced stress corrosion cracking (SCC) makes it particularly valuable in marine environments.
Pulp and Paper Industry: Alloy 28 is employed in the pulp and paper industry, where it is used in corrosive processes such as pulp bleaching and chemical recovery. It is suitable for equipment such as digesters, bleach towers, and evaporators, where corrosion resistance and reliability are crucial.
Pharmaceutical and Biotechnology Equipment: Due to its excellent corrosion resistance and hygienic properties, Alloy 28 is utilized in pharmaceutical and biotechnology equipment. It is commonly used in the manufacturing of vessels, tanks, and process piping for the production of pharmaceuticals, vaccines, and other biotechnological products.
Heat Exchangers and Condensers: Alloy 28 is utilized in heat exchangers and condensers in various industries, including chemical processing, power generation, and desalination. Its resistance to corrosive environments and high-temperature stability make it suitable for efficient heat transfer in demanding applications.
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