Plumbing: Pipes and Pipe Fittings

The type and size of pipe you can use in your home is regulated by plumbing codes. Before undertaking any plumbing job, check your local codes to determine whether you need a permit and to find out what restrictions exist on pipe types and sizes. Generally, water-supply pipes may be approved plastic, copper, galvanized steel or brass. Drain waste vent (DWV) pipes may be approved cast iron, copper, plastic or steel.

Fittings join sections of pipe. A large variety of fittings exist for connecting pipes of different types or diameters, for making curves with rigid pipe or for joining sections of pipe in straight runs or branches. If you can't find a single fitting to make a particular connection, try a combination of two or more.

Fittings are often available in two styles -- standard and flush wall. Standard fittings are used for water-supply pipes. Flush-wall fittings are needed for drainage pipes -- they have smooth inside joints that offer no obstruction to the flow of waste.

Rigid pipes are always referred to by their inside diameter (i.d.). However, the nominal size of a pipe sometimes bears little relation to its actual size. A pipe that's labeled 1/4 in. may actually be slightly larger or smaller than that. If you are buying pipe to connect to an existing line, measure the pipe's actual inside and outside diameters and , if possible, take a fitting or a piece of pipe with you to the plumbing supply store.

Always pick up valves or caps for the pipes you're working with so you can seal the system if you can't complete the project


Copper Pipe Fittings (shown on right)

No-stop coupling. Used to join copper pipe when there's no space to drop pipe into hub. Most useful for repairing damaged copper pipe.

Street elbow. Differs from standard elbow by having one hub-less joint to allow tighter turns.

45-degree elbow. Allows a gradual turn in rigid pipe systems, with 22.5° curves.

Male adapter. Transitions from soldered or cemented joints to threaded joints. Female adapters also available.

Cast drop-ear elbow. Ears allow firm support of pipe, and its female threads accept shower arm or other threaded fittings.

Cast-copper tee. Designed to provide easy installation of washer supply shutoff valves. Has female threads to accept valve.

PVC Pipe Fittings

Vent elbow. A tight- turning 90° elbow to be used only with venting system. In drains, it would interfere with using augers (snakes).

Sanitary tee. Used for 90° connection in drain line, usually to join vent, fixture drain and main drain.

Wye. Connects horizontal branch line to horizontal drain line at 45° angle.

Steel Pipe Fittings

Reducer coupling. Joins pipe of different sizes. Available for threaded, soldered, cemented and compression-type joints.

Pipe cap. Used to seal stub-outs or out-of service pipes. Plugs with male threads also available.

Dielectric and Other Unions

When joining pipes made of different materials, particularly copper and galvanized steel, use dielectric couplings to prevent deterioration. Other types of unions include (continue ...)...


Recommended Products

More | go to top of page

If you need supplies, tools or equipment for your DIY project, we recommend these trusted online merchants...

...they will deliver even the big stuff right to your door -- all at very reasonable prices.

Want to learn more about plumbing? Visit our plumbing library.

If you need plumbing supplies, browse through the products on these pages:

Got a wet basement? Visit our site dedicated to Basement Waterproofing. Save on all Faucets!

CPVC transition union compensates for thermal expansion between CPVC and copper or steel piping.


Flare-end connector fittings help make the transition from threaded-steel pipe to flexible, corrugated gas line.

Transition couplings with neoprene rubber sleeves and metal jackets make the transition from ABS pipe to PVC, from plastic to steel, and with other dissimilar materials. Always check label for approved uses.

Last modified: Friday, 2016-03-18 7:47 PST