Duplex Steel Flanges are commonly used for industrial, commercial, and institutional application. These flanges are steel pipe flanges are available in variety of styles and pressure classes. These flanges are a method of connecting pipes, valves, pumps and other equipment to form a piping system. Duplex Steel Flanges also provide easy access for cleaning, inspection or modification. These flanges are usually welded or screwed. These flanges are placed on pipe and fillet welded from both inside and outside.