What Is a Sink Flange?

Lori Kilchermann
Lori Kilchermann
A sink flange is used to attach a drain pipe to a sink.
A sink flange is used to attach a drain pipe to a sink.

A sink flange is a device used to connect a sink with a drain pipe. Typically made with a threaded design, a sink flange is attached to the sink prior to the drain pipe connecting to the flange. Both gaskets and plumber's putty are used to prevent leaks from a sink flange when it is installed. Flanges are made of metal, plastic blends and polymers and are offered in a variety of colors.

In order for a sink to properly dispose of water and any other materials that might be found in the sink basin, a sink flange is used to attach the drain pipe to the sink. The sink flange is commonly a two-piece design, including the actual flange with a collar. The collar is threaded onto the bottom of the flange and tightened against the sink in order to properly secure the sink. For most sink flange installations, silicone sealer is not used, but a small piece of plumber's putty is rolled into a cylindrical shape and placed around the sink's drain opening. The flange is pushed into the drain opening and nestled into the putty until the excess putty is pushed out around the flange.

Once settled into the putty, a gasket is placed up and over the bottom of the flange and the connecting ring is slid up and onto the bottom of the flange and tightened. The ring is tightened until snug and the excess putty that had squeezed out from around the flange lip is wiped clean from the inside of the sink. The drain pipe connection is then fastened to the bottom of the flange, and the system is tested for leaks by running water. The sink is also plugged and allowed to sit filled with water to check for leaks around the flange.

Early flanges were available in chrome-plated steel or brass fittings only, however, flanges are now manufactured in several colors to match sink colors and granite counter top colors. Commonly manufactured from plastic and cast resin, colored flanges blend into the sink and lend a unique appearance to an often-overlooked area. Some flanges are offered in black, white and off-white, colors which are intended to complement the color of the sink involved in the installation of the flange. Another feature common to nearly all sink flange designs is the inclusion of a stopper or a screened basket with the purchase of a flange.

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    • A sink flange is used to attach a drain pipe to a sink.
      By: djtaylor
      A sink flange is used to attach a drain pipe to a sink.