Fitting shapes: elbows, tees, couplings

Entry in Fittings and valves · Updated October 29, 2026 · Written by the Know Your Pipes editors from the sources listed under References

The types of pipe fittings in a house come down to a few shapes: elbows turn a run, tees and wyes branch it, couplings and unions join it, reducers change size, and caps and plugs close it.^[1][2] Each shape is made in every pipe material and joining method, from soldered copper to solvent-welded plastic to threaded steel.

Pipe makers say changes of direction should be made with fittings rather than by heating and bending rigid plastic pipe, which can damage it.^[3] Fittings are named by shape, size and end type, and the same shape can differ between pressure (supply) and drainage patterns. A catalog entry such as a 1/2 in 90° elbow, socket by socket, gives all three facts at once: size, shape and the joining method on each end.^[2]

1 Elbows and bends

An elbow, or ell, turns a run by a set angle. Pressure fittings are commonly made as 90° and 45° elbows, including a "street" elbow with one spigot end that fits directly into another fitting's socket.^[2] Drain fittings use the older "bend" names, which describe the fraction of a full circle the fitting turns.^[1]

Drain bends also come in short sweep and long sweep patterns, and pressure lines use special elbows such as the drop-ear elbow.^[1][2]

2 Tees, wyes and crosses

A tee has three openings (socket by socket by socket in plastic), and a cross has four.^[2] Drain systems use patterned branch fittings instead: the sanitary tee, the wye and the combination wye and eighth bend, along with tees and wyes that carry extra side inlets.^[1] Which of these is allowed in which direction of flow is set by the plumbing code; see sanitary tee and wye. Reducing tees have a branch smaller than the run.^[2]

3 Couplings, unions and reducers

A coupling joins two pipe ends of the same size; a reducing coupling joins two sizes.^[2] A reducer bushing has a spigot outside that fits into a larger fitting's socket and a smaller socket inside.^[2] A union has three separate parts and lets a line be taken apart later for repair or replacement without cutting; it should not be used to pull misaligned piping together.^[3] A dielectric union adds insulation between dissimilar metals.

4 Ends, caps, plugs and adapters

Spec sheets list a fitting's ends with short codes. One maker uses S for socket, SPG for spigot, MPT for male pipe thread and FPT for female pipe thread, so a plastic male adapter is "S x MPT" and a female adapter "S x FPT".^[2] A cap fits over the end of a pipe (socket end); a plug threads into a fitting (male thread end).^[2] Adapters and transition fittings change joining method or material, as covered under threaded pipe joints and solvent-weld joints.

Drainage-pattern fittings are made for gravity flow and are not for pressure use.^[3] Sizes follow the pipe's nominal size, not its measured diameter. Supply houses group fittings by material and shape; PlumbingSupplyAndMore's fittings category (PlumbingSupplyAndMore has the same owners as this reference) is one example of that layout.