Alloy 20 flange DN25 Plane Raised Face PN10 is a highly corrosion-resistant alloy used in industries such as chemical, oil and gas to handle corrosive media such as sulfuric acid and nitric acid. HT PIPE is a leading stockist and global exporter with over 15 years of expertise in international trade. We supply pipes, plates, round bars, and a comprehensive range of pipe fittings, flanges, and valves. Contact us now for free quotes and personalized product information.
Core Parameters and Standards
Nominal Diameter (DN): DN 25 indicates that the nominal diameter of the flange is 25 mm, corresponding to a 1-inch British Standard Size (NPS). This is a standard connection size used in piping systems to connect valves, fittings, and other equipment.
Pressure Rating: PN 10 indicates that the maximum permissible working pressure of the flange at the reference temperature is 10 Bar (approximately 1.0 MPa).
Sealing Face Form: Raised Face (PL/RF). This sealing face has a raised sealing surface on the flange surface, which, when used with semi-metallic gaskets such as spiral wound gaskets, can form an effective seal.
Alloy 20 Material Properties
Corrosion Resistance: Particularly resistant to sulfuric acid, phosphoric acid, and chloride stress corrosion cracking.
Balanced Chemical Composition: Its typical chemical composition includes approximately 20% chromium (Cr), 35% nickel (Ni), and 2-3% copper (Cu) and stabilized niobium (Nb).
Mechanical Properties and Machinability: Possesses high strength and good toughness, meeting the mechanical strength requirements of flanges in pressure piping connections, and is easy to machine and weld.
Alloy 20 flange Dimensions and Structural Features
- Flange Outer Diameter: The outer diameter of the flange.
- Bolt Hole Center Circle Diameter: The diameter of the circle in which the bolt holes are distributed.
- Bolt hole diameter and number: Specifies the diameter of the bolt holes and the number of bolts.
- Flange thickness: The overall thickness of the flange.
- Sealing face boss height: The height of the raised face (RF).
- Structural form: The connection method between the flange and the pipeline may include slip-on welding, butt welding, threaded connection, etc.
manufacture process uns n08020
Forging Process: High-quality flanges are typically produced using closed-die forging. This process uses high temperature and pressure to cause the metal grains to flow, forming a continuous fibrous flow, which eliminates casting defects and improves the flange's mechanical strength and impact toughness.
Heat Treatment: After forging, solution annealing is required. A typical process involves heating to 1050-1150°C followed by rapid cooling (water quenching). This process dissolves carbides precipitated during processing, obtaining a uniform austenitic structure, restoring the material's optimal corrosion resistance, and eliminating internal stress.
Machining: Finishing is performed using CNC machine tools to ensure that critical dimensions such as the flange's sealing surface and bolt holes meet the tolerance requirements of DIN 2576. Sharp carbide cutting tools and appropriate cutting parameters are required during machining to address the strong work hardening tendency of Alloy 20.
