Reducing flanges, otherwise called reducer flanges, have an opposite function than expander flanges seen above, i.e. they are used to decrease the bore of a pipeline.
The bore of the run pipe can be safely reduced by only 1 or 2 sizes (otherwise a solution based on the combination of a butt weld reducer and a standard flange has to be used).
Reducing flanges are available in most sizes and material grades, and are not generally available from stock.
Reducing flanges follow the same considerations in terms of specifications, sizes and material grades as expander flanges.
The last type of forged product that resembles the shape of a flange is the so-called spectacle blind: while not properly a flange, a blind (or a ring spacer or spade) is used in between pipes to isolate the pipeline mechanically and in a very easy way. More details are provided in another section of our Wiki for piping.