Duplex flanges are high-strength fittings corrosion-resistant in demanding environments. It is a combination of austenitic and ferritic stainless steels, thus giving ultimate strength, durability, and resistance to stress cracking corrosion. The application place includes oil and gas, chemical, and marine industries. Due to their composition, duplex flanges are more efficient and chea... https://www.greatmetal.com/duplex-steel-flanges.html