A reducing flange is a type of flange that is designed to connect pipes of different sizes. It has a larger diameter on one end and a smaller diameter on the other end. The larger end of the flange is bolted to the larger pipe, while the smaller end of the flange is bolted to the smaller pipe.

Reducing flanges are commonly used in piping systems where there is a need to reduce the size of the piping, either to accommodate flow requirements or to connect pipes of different sizes. They are available in a variety of materials, including carbon steel, stainless steel, and alloy steel, and can be designed for both standard and high-pressure applications.

Reducing flanges are typically used in combination with a gasket and a set of bolts. The gasket is placed between the flange faces to prevent leakage, and the bolts are tightened to a specified torque to hold the flanges securely together.

One advantage of reducing flanges is that they can simplify the piping system by eliminating the need for a separate reducer. However, they are generally more expensive than other types of flanges, and require careful consideration of the flow requirements and compatibility of the materials used in the piping system.