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All About Fittings

Fittings allow pipe to be installed and joined where necessary and terminated in the appropriate place. Each kind of pipe requires its own type of fitting, but all fittings share some common features.

1. Fittings are either male or female
   This refers to their orientation at the connecting point. Pipes, nipples, and male fittings insert into female fittings. In threaded fittings, male threads are on the outside and female threads are on the inside. Fittings that have one male end and one female end are called street fittings.
   
   
2. When measuring the size of fittings, male threaded fittings are measured OD, or to the outside edge, while female fittings are measured ID, or to the inside edge of the inlet.
   
   
3. Fittings are generally made in one of two standard sizes, IPS (Iron Pipe Size) or CTS (Copper Tube Size). These two standards are not compatible and require adapters to connect them. Male IPS fittings are abbreviated "MIP" and female IPS fittings are abbreviated "FIP"
   
   

Most DWV fittings are available with vent inlets if needed, but pressure fittings are not because pressure lines are not vented. All types are also available as reducing fittings.

Sometimes a situation calls for an unusual fitting that may not be available or that we do not stock, but very often multiple fittings can be combined to form an equivalent item. For example, a 45 street ell can be added to a wye fitting to simulate a tee wye.

Nipples are not really fittings but rather short lengths of pipe. We sell threaded steel nipples in lengths from "close" (close nipple threads almost join in the center) to 6", in ½" increments, and from 7" to 12" in one inch increments. We sell longer nipples as custom-cut pipe in any length.

The use of a specific fitting is often dictated by the space available to install it. Regardless of preference, plumbing contractors often have to install an alternate choice because of the room they're given.

Fittings can be grouped in one of several categories.

Fittings that extend or terminate pipe runs:

Couplings extend a run by connecting two lengths of pipe. They are available in all standard pipe sizes and nearly all varieties of pipe. They're called reducing couplings if they're connecting different sized pipe.

Adapters are similar to couplings, but they connect different types of pipe, one of which is an IPS size. Unions are three-part mechanical fittings that connect any two standard size pipe in such a way that they may be disconnected and reassembled with a pipe wrench. Unions provide the easiest method for dismantling pressure pipe.

Caps and Plugs end a run of pipe by closing it off with a watertight seal.

Fittings that change a pipe's direction:

Elbows (ells) change direction of pipe. Most common are 90o and 45o elbows, but are also available in 22 ½ and 60. They are identified by their angle but they are ordinarily referred to by number only. An ell may be female at both ends, or in the case of a street ell, may be male on one end and female on the other. Some are offered in a long-turn variety, some have side inlets; some have vent inlets.

Fittings that Connect two or more pipes:

Tees offer the most varieties of any type of fitting. Tees are fittings in the shape of a "T" where the top of the "T" is the continuous pipe run, and the vertical section is a branch connected to it. They may be reducing tees, where the branch and/or one end of the thru section is a smaller diameter than the inlet. They may have side-inlets, that make them Crows Feet Tees, which allow for a fourth pipe to join them. These may be left or right handed depending on which side the inlet enters. They may even have twin side inlets in a shotgun or owl's eye fashion.

If the branch line passes through the tee, the fitting becomes a Cross. If the side inlet passes through the fitting, it would be a four-way tee. If the cross has a side inlet, it could accommodate 5 different pipes. Tees can be used with cleanout plugs in a soil stack. Other tees in the soil stack are often sanitary tees, in which the branch line connects in a curved manner, which reduces the friction in the pipe, thus less likelihood of clogging.

Side-inlet Elbows have three-way outlets. They can be used as corner pieces for railings, fences, etc. but are also used for pipe connections on corner construction.

Wyes are similar to tees except that the branch line is angled to reduce friction that could hamper the flow, and the connection is typically at a 45-degree angle rather than a 90-degree angle. If a branch turns out at the end to be perpendicular to the through line the fitting become a tee wye.

Fittings that change pipe size:

Reducers can be couplings, tees, ells, or wyes, where one end is smaller than the other. This reduces the pipe's diameter between inlet and outlet. In the case of fittings that connect more than two pipes, one of the outlets is of a smaller diameter, (not counting side-inlets, which are always smaller). Some reduce pipe only one size; others can reduce several sizes. Both ends are female.

Bushings serve the same purpose as reducers except that they have one male and one female end. In steel pipe, they are threaded inside and out; instead of screwing directly onto pipe threads, they screw into a coupling and pipe is threaded into them. They are virtually invisible once installed. In PVC and copper they are not threaded but work the same way.

Couplings connect pipe to pipe. Couplings with stops usually have tiny ridges or "stops" on the inside to seat the pipe. When they don't, they're called "repair couplings" that can be positioned anywhere along a length of pipe to repair a leak. Both ends are female.

Flex couplings are rubber couplings used to join DWV Pipe. They can be used to connect PVC to Clay or Cast Iron above or below ground. Also used for repairs. They attach by used of steel band clamps, and are suitable for repair of damaged DWV lines or as underground adapters to connect PVC to Clay or Cast Iron pipe. They are not suitable for pressure connections.

Fitting reducers connect pipe to fittings. Fitting reducers look like couplings but they're actually bushings used primarily with copper fittings to reduce the size of a run. One end is female; the other male.

Adapters connect dissimilar types of pipe. They may have either male or female IPS threads on one end and the opposite gender on the other end to be soldered or welded onto a smaller pipe. Flex couplings can act like adapters.

Misc. Fittings:

Floor Flanges connect pipe to a wall, floor or any flat surface. Flanges are threaded onto pipe and tightened. This provides a flange rim with four screw holes, making it easy to fasten pipe to a flat surface.

• Cast Iron
• Copper
• Malleable
• Plastic

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