Reducing flanges are designed for use in changing diameters in a piping system. A reducing flange comprises a flange with one specified diameter having a bore of a different and smaller, diameter. Except for the bore and hub dimensions, the reducing flange will have dimensions of the larger pipe size. These flanges are used at the outlet side of the expansion joint to increase the size of the flange. This is considered to be an economical method to make a transition in size.