How to Choose Pipe Fittings?

Plumbing is all about pipes and fittings. Pipes establish the runs that bring or take water, with fittings controlling and manipulating the flow. Pipes are simple enough: they're straight, and come in different sizes. Pick the right material and length, and you're pretty much good to go. Fittings - for a plumber - are much the same. But for the average homeowner, there are a lot of fittings. Some can be perplexing, others downright intimidating once materials and sizing are considered. The sizing we'll explore in another article; for now, you can learn a little bit about the most common fittings found in your home's plumbing. Never again will you need to ask for "the thingy with the two ends that connects the two pipes at an angle"!

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Different Fitting Types

Adapters

Adapters are used to extend runs, or to simply change the connection type at the end of a pipe. This allows dissimilar pipes to be connected, without the need for a more involved setup.

Adapters are available in most all standard materials: ABS, brass, copper, CPVC, malleable (galvanized and black), PVC, and stainless steel.

Bushings

Bushings are used to join pipes of different sizes, usually by reducing a larger fitting down to a smaller pipe. Bushings are usually - not always - threaded both inside and out, and take up very little space compared to a coupling or union, which accomplish the same goal.

Offered in: ABS, brass, chrome-plated brass, copper, CPVC, malleable (galvanized and black), PVC, and stainless steel.

Note: Some fitting types, like bushings, have limitations placed on their use (or are not allowed at all) by some plumbing codes. Remember to check local plumbing codes prior to purchasing.

Caps & Plugs

Caps are, surprisingly enough, used to cap a pipe end. Plugs do pretty much the same thing, but usually fit inside the fitting, and are threaded to allow for future use of the pipe. Caps can be threaded, glued, or soldered onto pipe (depending on its material).

Both are available in: ABS, brass, chrome-plated brass, copper, CPVC, malleable (galvanized and black), PVC, and stainless steel.

Couplings

A coupling is used to extend the run of a pipe, or change pipe sizes (in the case of a reducing coupling, also sometimes called a "bell" reducer due to its shape). Available with female threads, or unthreaded for either plastic gluing (solvent welding) or copper soldering, these are among the most-used of fittings.

Offered in: ABS, brass, chrome-plated brass, copper, CPVC, malleable (galvanized and black), PVC, and stainless steel.

Elbows

If you need to change the direction of flow, elbows are likely your best bet. Produced primarily in 90 and 45 degree angles (unique sizes like 22.5 and 60 are also available), elbows can be threaded or sweated, and are one of the most crucial fittings used in plumbing. Street elbows feature male and female threaded ends to easily connect differing pipes or fittings. Some unique elbows also feature a side outlet, making it act more like a tee with a bend.

Available in: ABS, brass, chrome-plated brass, copper, CPVC, malleable (galvanized and black), PVC, and stainless steel.

Flanges

Flanges are used to connect pipes. Pipe is threaded or welded to the flanges, which are then sealed together (usually with bolts). Flange connections are used extensively in industrial applications handling high pressures. They can also be found connecting residential pump systems. "Closet" (or toilet) flanges are found in the home mounting the toilet to the floor and drain beneath.

Offered in: brass, copper, malleable (galvanized and black), and PVC (for closet/toilet flanges).

Nipples

Nipples are a short stub of pipe, male-threaded at each end, that are used to connect straight pipe runs. Close nipples are threaded from each end along their whole length for particularly tight connections.

Available in: brass, chrome-plated brass, copper, malleable (galvanized and black), PVC, and stainless steel.

Tees

When more than one branch is required of a water supply, tees are the way to go. Essentially a long coupling with an outlet on the side, these fittings feature their outlets at 90° from the inlet, and are sized according to their "run" (the horizontal, or straight-through dimension of the fitting), and the side outlet (the "top" of the fitting, 90 degrees off the run). When the run of a tee is smaller than the side outlet, it's often referred to as a "bull head" fitting.

Tees are offered in ABS, brass, chrome-plated brass, copper, CPVC, malleable (galvanized and black), PVC, and stainless steel.

Crosses

"Cross" fittings are 4-way fittings that are essentially the combination of two tees. Many opt to use two tees instead.

Crosses are available in brass, malleable (galvanized and black), and PVC.

Saddle Tees

These fittings are used to quickly add a tee to an existing length of pipe, without having to cut and re-solder what's there. Most often, this takes place with irrigation systems to add a new sprinkler line. Also referred to as snap-tees, saddles are glued to the pipe, and after setting, the new hole is drilled.

Saddle tees are offered only in PVC.

Unions

Unions are an alternative to couplings, when the latter are impractical or inconvenient. Whereas couplings (when not soldered) need to have pipe threaded into them, unions rely upon their own nut to create a seal between the pipe ends. This makes them the perfect choice for connecting two fixed pipes (that are unable to be threaded into a regular coupling), and make future repairs that much easier. Dielectric unions are used to join pipes of different metals by providing a barrier against galvanic corrosion. For all their benefits, unions do have drawbacks: they are not to be used with natural and LP gas.

They are available in in brass, chrome-plated brass, copper, CPVC, malleable (galvanized and black) PVC, and stainless steel.

Wyes

Wyes are primarily drainage fittings, and feature a 45° branch line designed to keep flow smooth. While sanitary tees are used with vertical drain connections, they can cause problems when used flat on a horizontal connection: those situations call for a wye.

These are available in brass, ABS, and PVC.

Common Fitting Materials

ABS

Acrylonitrile Butadiene Styrene, a black plastic used in drainage, sewer, waste and vents. ABS pipe/fittings as well as PVC have replaced much of the cast iron, lead, and steel pipes formerly used for DWV. Important to note is that no solvent cement (or primer) can totally "glue" (solvent weld) ABS to PVC plastic.

Brass

Made with a mixture of metal alloys: mostly copper and zinc, as well as small amounts of lead, tin, manganese, nickel, aluminum or iron. Brass fittings used for potable water usually have approximately 62-65% copper, 30-35% zinc and very small percentages of tin and lead. Brass works particularly well in hot water applications, and is highly resistant to corrosion.

Copper

Reddish-brown, non-ferrous metal widely used for household plumbing pipes. Copper is a relatively soft and often thin material, making threading difficult. As a result, most copper fittings are not threaded, and must be soldered to copper pipe.

CPVC

Chlorinated Polyvinyl Chloride is a plastic product designed for drinking water at temperatures up to 180 degrees (where code permits), and can generally withstand higher temperatures than standard PVC. The CPVC fittings we offer will not glue on PVC schedule 40 pipe.

For more information, please visit Submersible Pump.

Malleable (Galvanized or Black)

Made from steel. Black iron is mostly used in gas and oil applications, and is often coated with black paint or lacquer. Galvanized fittings are coated with zinc to protect against rust and corrosion. Galvanized piping was widely used for home plumbing in the past, but no longer, due to leak issues over time. Galvanized fittings today are most often used for non-potable outdoor applications, and to repair existing galvanized systems.

PVC

A rigid, generally white plastic pipe. Used for waste and vent systems as well as cold water (underground) supplies outside of the house as well as used for sprinkler and irrigation pipes, sewers, drains, wastes and venting pipes and fittings. PVC in the plumbing business is generally white (Sch 40) but sometimes comes in other colors (in our industry gray is the second most popular, and is typically used for Sch 80 PVC). Another color you may see more frequently as water conservation efforts grow is purple, which is used to differentiate reclaimed or grey water systems from potable drinking water systems.

Stainless Steel

A combination of iron alloys and chromium, stainless steel is durable and offers excellent rust and corrosion resistance. Stainless steel comes in many types, with 304 and 316 being the most used in plumbing. Both are rated to pressures of 150 psi, with type 316 steel providing greater protection against chemical corrosion.

I doubt there&#;s a DIY plumber out there who hasn&#;t experienced the frustration making multiple trips to the hardware store to complete a repair. I know I have.

Putting together a network of pipes of different diameters and materials can be like assembling a puzzle. Sometimes you don&#;t know exactly which fitting to buy until you reach the part of the puzzle where you need it.

Plumbing fittings vary by size, purpose and material. You often must tie together pipes of different materials with transition fittings. The materials in common use today &#; copper, PVC and CPVC, PEX, ABS, galvanized steel and cast iron &#; can mostly all be connected to each other with appropriate fittings.

With all the different pipe sizes and materials out there, things can get confusing. Fittings for water lines are different than those for drain and waste lines. It&#;s no wonder professional plumbers don&#;t go anywhere without a truck full of fittings. It&#;s their magic cupboard, letting them complete installations and repairs much more efficiently than amateurs like me.

Water Line Fittings

PEX is quickly becoming the material of choice for water lines. But PVC, CPVC and copper are still in common use, as is galvanized steel outdoors.

Three reasons for PEX&#;s popularity are its flexibility (it can bend around corners), durability and ease of assembly. You simply push PEX pipes and fittings together rather than gluing (PVC and CPVC), soldering (copper) or screwing them (galvanized steel).

Here are the fittings you&#;re most likely to need when assembling or repairing water lines:

• Coupler: Joins two lengths of pipe in a straight line. Whenever you cut a pipe during a repair, you&#;ll need a coupler to put it back together.
• Bend: For changing pipe direction. The most common bend angles are 90 degrees (aka elbows) and 45 degrees. Bends are typically made of the same material as the pipe except for PEX bends, which are brass or hard plastic.
• Tee: Shaped like the letter &#;T&#; with two parallel ports and a perpendicular one. It&#;s used for adding a branch line. When the branch line is a different size than the main one, you can make the connection with a reducing tee.
• Reducing adapter: Another way to join pipes of different diameters. It may be shaped like a bell (common for copper and galvanized pipes) or fit inside the larger pipe (more common for plastic). The first type is a bell adapter, and the second a reducing bushing.
• Union: A type of coupler you can take apart. Its large threaded nut holds together the two halves of the connected pipe. You can use one in place of a coupler in any situation where you temporarily disassemble the pipes.
• Threaded adapter: To join a pipe with a glue or solder slip joint to one with threads, you&#;ll need a threaded adapter. It can have male or female threads. Threaded adapters join plastic pipes to each other, or copper to itself or to brass.
• Compression fitting: This lets you join plastic or copper pipes without glue or solder. Most feature a ring that fits around the pipe and a nut that tightens onto the fitting, wedging the ring into the gap between the pipe and fitting. Compression fittings allow for easy pipe repair. Most modern faucet and toilet shutoff valves have compression fittings.

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Waste and Drain Fittings

Cast iron was a common material for drain pipes in the first part of the 20th century. They&#;re usually connected with couplers that feature rubber gaskets surrounded by stainless steel sheathing.

These days, most drains are made with PVC or ABS plastic. Plastic drain fittings are usually glued, but the ones you might need to remove temporarily, like cleanout plugs, are threaded.

Here are the most common drain fittings. The list doesn&#;t include couplers and ordinary bends, because they&#;re similar to the ones used for water pipes and serve the same purposes.

• Long-sweep elbow: Makes a 90-degree bend in a longer arc than an ordinary elbow to allow water to flow more smoothly. It&#;s used for connecting vertical drain lines to horizontal ones.
• Straight tee: Performs the same function as tees for water lines, but are seldom used for drain lines. They&#;re mostly for vents, tying horizontal pipes to vertical stacks.
• Sanitary tee: Aka a santee, this has a sweep on its perpendicular port to promote water flow in the direction of the sweep. Use it to connect a horizontal waste line to a vertical one, but not a vertical one to a horizontal one. That&#;s the job of the next fitting.
• Wye: Shaped like the letter &#;Y,&#; a wye does the same job as a sanitary tee, but with less chance of backflow. This is the fitting you need to connect the vertical drain from your sink or toilet to the sewer. You can also use it to connect a horizontal waste pipe to a vertical one.
• Double wye: As you might expect, this has two inlet ports instead of just one. It&#;s commonly used for connecting a double-basin sink to a single P-trap.

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Transition Fittings

Whether you&#;re connecting PVC or CPVC pipes to copper, cast iron pipes to ABS or galvanized pipes to copper, you&#;ll need a transition fitting. In some cases, you can do it by taking two threaded adapters of different materials and screwing them together. But it&#;s often easier to use an adapter specifically made to couple them, assuming you can find one.

• Plastic-to-copper slip adapter: This fitting has male copper threads on one end and a PVC or CPVC slip joint on the other. After soldering a female thread adapter to the copper pipe, you screw in the adapter and glue the plastic pipe to the slip joint.
• Dielectric union: Used for mating copper or brass to galvanized steel, its insulating washer keeps the pipes electrostatically separated to prevent corrosion. Dielectric unions are commonly used when installing water heaters.
• Cast iron to plastic coupling: These are widely known as Fernco couplings after the company that makes most of them. They consist of a rubber cylinder surrounded by a stainless steel sheath and two or more threaded pipe clamps tightened with a screwdriver.

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