Closet flange

In plumbing, a closet flange (also known as a toilet flange) is a pipe fitting (specifically, a type of flange) that both mounts a toilet to the floor and connects the toilet drain to a drain pipe. The name comes from the term "water closet", the traditional name for a toilet. A typical closet flange is composed of an ABS or PVC hub with a round steel mounting flange attached to the top. Other styles are made from copper, brass, stainless steel, or pure plastic.

PVC closet flange with steel flange, before installation

In a typical installation, the closet flange is mounted on top of the floor with the hub fused around the drain pipe. A wax ring is used to seal the gap between the flange and the bottom of the toilet. The toilet is bolted to the flange, not to the floor.