Duplex and super duplex steel flanges are a type of stainless steel flange that has a two-phase microstructure consisting of ferrite and austenite. This gives them a number of advantages over other types of stainless steel flanges, including: Higher strength: Duplex and super duplex steel flanges have a higher yield strength than other types of stainless steel flanges, making them more resistant to deformation and cracking. Better corrosion resistance: Duplex and super duplex steel flanges have better corrosion resistance than other types of stainless steel flanges, making them suitable for use in harsh environments. Lower thermal expansion coefficient: Duplex and super duplex steel flanges have a lower thermal expansion coefficient than other types of stainless steel flanges, making them less susceptible to thermal stresses. â?¢ Duplex & Super Duplex Steel Flange : ASTM A182 / ASME SA182 F44, F 45, F51, F 53, F 55, F 60, F 61 The technical specifications of duplex and super duplex steel flanges vary depending on the grade of steel and the application. However, some common specifications include: Pressure rating: 150# to 2500# Temperature rating: -200�°C to 300�°C Dimensional tolerances: ANSI/ASME B16.5 Finish: Smooth, blasted, or electro polished