Flange tables are chiefly used to identify the standard of flange used on pre-installed plumbing devices, such as toilets. Flanges are rings or hollow plates that connect two or more pipes together.
Flange tables contain information on the dimensions, bolt size, and number of bolts used on a variety of standard flanges. This information allows plumbers and people engaged in home repairs to correctly identify the flange used on a piece of plumbing. Knowing the standard makes it easier to replace the flange, or to find an appropriate substitute.
Flange standards are international and are in accordance with ASME's B16.5 specification, so a flange found anywhere in the world should match at least one of the standards found in the specification.