If you’ve never had to make repairs to your plumbing, you may not realize just how many different types of plumbing fittings exist. Fittings are plumbing pieces that connect two pieces of pipe.
Identifying these fittings by sight can help you if you ever have to make repairs or inform a repair specialist about your problem. Plumbing fittings come in a wide range of types, including different materials, abilities, and shapes. First, we’re going to look at some of the most common types of plumbing fittings.
We’ll also look at the different types of materials that plumbing fittings can come in. And we’ll explain when each type of fitting serves as the best choice, such as for certain pressure, temperature, or angle of operation.
Common Plumbing Fittings
There are multiple types of plumbing fittings. Understanding the design, features, and uses of the different plumbing fittings can help you know what types to use initially or if you have to replace the pieces.
Adaptor
Adaptors are essential for connecting pipes of different sizes or to join a female line with a male (or vice versa).
These fittings are both male – threads on the outside – and female – threaded on the inside on each end. This design allows them to connect to any pipe. So you can get adaptors in three types – female, male, or straight-threaded.
Fittings without a threaded end require welding or soldering to ensure the piece creates a secure hold with the pipe. Adaptors can handle high pressure, are leak-free, and make a smooth transition between tubing and piping systems.
Adaptors’ available materials include rubber, polymer, and metals like brass, copper, cast iron, aluminum, and steel.
Elbow
Elbow fittings are curved so that they can change the direction of the flow. You can find elbows at a 90 or 45-degree angle. To mount them, they come threaded or require sweating.
The elbow fitting ends can be threaded, butt welded, or socketed. To connect piping that is two different sizes, you can use a reducing elbow.
You can find elbows in materials like brass or chrome-plated brass, copper, ABS, CPVC, PVC, or stainless steel.
Coupling
A coupling is similar to a union, except you can’t detach two pipes connected with this fitting without causing damage.
You can use a coupling to connect pipes that are the same size. Or you can use a specific coupling fitting – a bell reducer – to attach two lines of different sizes.
Couplings come with unthreaded or female threaded ends. If you’re using unthreaded fittings, you’ll need to use a plastic solvent weld or copper solder to secure them in place.
Two other types of couplings to know about are compression – uses rubber seals or gaskets on the ends to prevent leaking of the connection between the two pipes – or slip – a fitting used to repair a damaged piece of pipe.
You can also get couplings in multiple types of materials, like chrome-plated brass, brass, ABS, PVC, stainless steel, or CPVC (chlorinated polyvinyl chloride).
Union 
Union fittings have three different sections – one male end, the other end female, with a nut in the middle. This design is handy for sections of connecting pipes that might have to be detached at some point.
Disconnecting the pipes will not cause any deformation or damage, making union fittings an excellent choice for planned replacements or in places that will receive frequent maintenance. You often see these in municipal and industrial settings, such as for wastewater systems or process piping.
You can get pipe unions in a large selection of materials, including cast iron, brass, nickel, rubber, plastic, or bronze.
Nipple
Pipe nipples are one of the most commonly used plumbing fittings. They serve a severe and crucial purpose in your home’s plumbing systems – it connects two pipes of straight pipe run together and connects appliances with the piping.
Nipples are easy to identify due to having a male adapter on both ends of the piece – threaded outside with a smooth inside that inserts into a female part.
And you have a pick from five different types:
- Hexagon – a hexagonal center with threaded ends; comes in various threads, lengths, and materials
- Weld – high resistance to vibrations and pressure surges make these nipples the best choice for connecting tube fittings
- Barrel – short and tubular with external taper threaded ends and an unthreaded middle
- Swage – transitions fluid between pipes of different sizes
- Close – aka running nipple due to both ends threaded throughout
You can get nipples in multiple materials, including aluminum, copper, brass, carbon steel, stainless steel, or PVC. But pay attention to the nipple’s diameter, material, and thickness to make sure you get the right size.
Reducer
The sole purpose of a reducer is to reduce flow. You have a pick of two types of reducers –
Concentric reducers join pipes on the same axis when a pipe diameter changes. These look like a cone. Eccentric reducers are best when the downstream line is smaller than the upstream pipe.
You can get reducers in limited types of materials, including stainless steel, carbon steel, or alloy.
Double Tapped Bushing
Double tapped bushings are a type of nipple with threading on the interior and outside of one end. The name is due to the center hole threaded (tapped) on the top and bottom. Most double-tapped bushings are female.
These bushing types also work as a type of reducer, although they do not have the same flexibility as a regular reducer.
Combo Tee
Combo tees have a central branch that gradually curves. This design makes this fitting perfect for drains, as the smooth slight curve reduces the possibility of clogs.
The curve is also easier for a plumbing snake tool to go through, removing any clog or blocks. Combo tees are also typically PVC.
Diverter Tee
Diverter tees are typically for pressurized hydronic heating units. The design allows portions of the airflow to divert from the primary line to a side branch that goes to a heat exchanger.
Even if the side branch gets shut off, airflow continues through the main stem.
The downside of diverter tees is that they can be challenging to install. There are directional markers, and it’s crucial to follow these. Installing a diverter tee backward will result in improper functioning.
You can find diverter tees in the same materials as other tees, including ABS, PVC, copper, brass, chrome-plated brass, or stainless steel.
Cross
A cross fitting is a four-way connector with one inlet and three outlets in a two tee design. You can get these with female threaded or solvent-welded socket ends.
Many people prefer to use tees over cross fittings because these pieces can cause stress on the pipes when the temperature changes. Because of this, crosses are more likely to be for plumbing situations when there’s no concern about thermal expansion, like sprinkler systems.
You can get cross fittings in materials like brass, malleable, PVC, steel, or stainless steel.
Cap
Caps create a liquid or gas-tight seal over the end of open pipes. You can attach these covers using a solvent-welded socket or by female threads.
And they come in a wide range of shapes, including rectangular, square, round, or shaped like a U or I. Some types of caps will have a handgrip.
You can also get caps in various materials like CPVC, PVC, ABS, copper, malleable, brass or chrome-plated brass, or stainless steel.
Plug
A plug has a similar function to a cap, except these pieces go inside the open pipe rather than fitting over it. In addition, most plugs have a threaded end, allowing them to be easy to remove in the future.
And also, like caps, plugs come in many similar materials, including copper, stainless steel, brass, or ABS.
Barb
Barb fittings are also easy to identify due to their unique shape. These fittings feature a male thread on one end with a ridged, tapered cone on the opposite end.
This design is so that once it goes inside a rubber hose, the fitting grips the insides of the wall, creating a secure connection. The hose will expand as the barb pushes inside. As the hose returns to a standard size, it seals around the barb.
Because it can be complicated to break this seal once it forms, barb fittings are commonly used for low-pressure air, fluid, and gas control applications. If using a barb fitting for water connections, you’ll need to use brass for hot water and plastic barbs for cold water.
Criteria for picking the proper barb fitting include the hose’s (or tube’s) inner diameter, how hard the hose material is – which can affect whether you’ll want to pick single or multi-barb – and material compatibility.
Valve
Valves control the flow of liquid or gas, turning it on or off as needed. Most valves fall into an application categorization.
- Isolation: temporarily disconnects a pipe system part to leave the pipe fully closed or open – lasts for years before needing replacement
- Throttling: controls fluid pressure, withstanding stress and wear (although it will fail eventually) – installing a throttling valve with an isolation valve gives a backup if the throttle fails.
- Non-return: lets fluids flow one way while preventing reverse flow, making them used commonly in drainage and sewage systems – also called check valves
Valves are typically a type of metal, including cast steel, cast iron, bronze, stainless steel, or carbon steel for high temperature and high pressure.
Wyes
Wyes are plumbing fitting in the Y shape, connecting to 45-degree branches, typically for drainage.
This angling of the branch reduces friction and turbulence when connecting vertical pipes to horizontal drainage pipes.
You can find wye fittings in materials like ABS, brass, or PVC.
Flanges
Flanges are round in shape and serve the purpose of connecting pipes. The connecting lines can attach by threading or welding them to the flange middle and sealing them. There are also holes on the outside of the flange to add bolts.
This design makes flanges excellent for industrial settings and residential pumps due to containing heavy pressure.
All toilets that mount to the floor should use a PVC flange – aka closet flange. Flanges can also come in other materials like brass, malleable, or copper.
Bushings
Bushings resemble small screws and are primarily for connecting different sized pipes, mainly for reducing a large fitting to fit smaller lines.
You can find bushings with threads on the inside and outside (male and female), but you can also find them with one or the other.
Because bushings are smaller than couplings or unions, these fittings are often used in similar places. You can find bushings in brass (or chrome-plated brass), malleable, copper, PVC, CPVC, or ABS.
Mechanical Sleeve
Mechanical sleeves connect two pipes using a device (usually a screw), making them simple to install. Most sleeves are rubber and insert inside a stainless steel clamp that compresses the rubber for a tight seal.
Because of the design, mechanical sleeves have some flexibility, making them useful in difficult places where you may not be able to use other fittings and rigid pipes.
Cleanout
Cleanout fittings have parts that you can remove to gain access to the drains without having to remove the plumbing fixtures.
The removable parts allow you to place an auger – a type of drill – into the cleanout to clear clogs in the drain.
You do have to be sure the cleanout is installed somewhere accessible. Also, augers aren’t very long, making it challenging to clean out longer pipe pieces.
In large plumbing systems, there are often multiple cleanouts at regular intervals. And almost all cleanouts are PVC material.
Common Materials Used To Make Fittings
As you can see from the different types of plumbing fittings, most options come in various materials. Let’s look at some of the most common material types used for plumbing fixtures.
ABS
ABS – acrylonitrile butadiene styrene – is a type of black plastic. This material is primarily for waste, sewer, drainage, and vents.
ABS – and PVC – has replaced the majority of lead, steel, and cast-iron pipes. However, it is essential to remember that no primer or cement can solvent weld (glue) ABS to PVC (plastic).
Brass
Brass fittings are commonly for potable water due to their performance in hot water. In addition, this material is more resistant to corrosion (rusting).
This material consists of a combination of metal alloys – mostly zinc and copper. But there are also small portions of tin, lead, nickel, iron, manganese, or aluminum. The brass must contain 65% copper and 30% to 35% zinc and low traces of lead and tin to be safe for potable water.
Copper
Copper is another metal used mainly for household pipes for plumbing. This material is quite soft and thin, which can make it flexible.
But this feature can also make copper harder to thread. Due to this difficulty, copper is more often soldered.
CPVC
CPVC – Chlorinated Polyvinyl Chloride – is a type of plastic that allows for safe drinking water up to 180 degrees temperature (if code permits).
CPVC can survive higher temperatures than regular PVC.
Malleable
Malleable is black or galvanized steel. This black iron fitting is more often for oil and gas purposes. The surface is typically coated with lacquer or black paint.
Galvanized steel fittings have a coating of zinc that prevents corrosion and rust. These fittings were used in the past for home plumbing, but due to the development of leaks, other materials are now used instead.
Nowadays, galvanized fittings are more primarily used for outdoor systems and non-potable situations. However, it may also be used to repair existing galvanized systems.
PVC 
PVC is a white plastic pipe best used for underground cold water systems and vent or waste systems. It’s also excellent to use for irrigation and sprinkler pipes, wastes and vent pipes and fittings, sewers, and drains.
Most PVC fittings in the plumbing industry are white. But gray is also a popular choice. Purple is starting to grow more popular to differentiate gray or reclaimed water systems from drinking potable water systems.
Stainless Steel
Stainless steel consists of a mixture of chromium and iron alloys. This steel is highly resistant to corrosion and rust.
You can get stainless steel in multiple gauges – 304 or 316 are the most common types used for plumbing. Both types have a rating of 150 psi, although 316 gives more protection against corrosion from chemicals.
Cast-Iron
Cast-iron fittings are used for storm and sanitary drains, vents, and waste pipes due to the material’s imperviousness to abrasions.
Cast-iron is also resistant to chemicals and high temperatures, making it an excellent material for transporting gases but not so well for water.
Connecting Fittings
Plumbing fittings serve the purpose of connecting two or more pieces of piping. Just as there are different fittings, there are also multiple types of ends connecting the fittings to the pipes. These different end types each have a unique way to connect.
Threaded
Threaded fittings connect by twisting the pieces to form a tight fit. Then, the threads align by pairing a male thread and a female thread.
The female fitting has threads on the inside that match up with a male fitting’s external threads.
Push To Connect
Push-to-connect fittings are the perfect choice for DIY projects, as they’re easy to install without the use of specialized tools. Rings and metal teeth make these fittings create an excellent connection for pipes made of PVC, copper, or PEX.
Slip
Slip fittings have smooth walls that slip onto plastic pipes. Due to the smooth nature, you have to use a primer followed by a quick-drying cement solvent to keep the pieces together.
Compression
Compression fittings feature a threaded body, a sleeve – ferrule – and a nut that creates a compression – a squeezing force – that pushes the pipe pieces together to create a tight joint.
Flare
Flare fittings feature a cone-shaped fitting and a flare nut that connects to the pipe after it’s been “flared” using a specialized tool. These fittings are excellent for gas and high water pressure applications.
Crimp
Once the fitting inserts inside the pipe, a specialized tool squeezes – or crimps – the metal ring that goes around the pipe.
Clamp
A clamp can tighten around the piece after placing a fitting into the pipe, holding the fitting together.
Types Of Plumbing Fittings FAQ
Below are a few frequently asked questions people have about different types of plumbing fittings.
What Are the Piping System Types?
There are three piping system types – stormwater drainage, potable water, and sanitary drainage.
How Do You Know Which Fitting You Need?
To figure out the type of fitting you need, consider what kind of piping or tubing you’re using to ensure you get material compatibility. And pick the suitable material for the fitting’s pressure and temperature condition.
Where Do You Buy Plumbing Fittings?
You can buy plumbing fittings at any home improvement or plumbing store. You can also order them online.
Conclusion
This guide covered the multiple types of plumbing fittings that are used in residential and commercial settings. Identifying the different fitting types can help you make repairs easier by knowing what fittings you need. Fittings come in different shapes, materials, and capabilities. Which style is best for your needs will vary by job.
