To work on plumbing lines, whether for drinking water or wastewater, you need to know the types of pipe fittings available to you.
Let’s face it, in addition to piping, you also need fittings (also known as connectors) to join them together. And that’s what we’re going to learn about in this article.
What is a Pipe Fitting?
A pipe fitting is nothing more than a connector. The fitting connects two or more pipes to each other. They come in many different materials, such as copper, to cast iron, steel, brass, and plastic.
A fitting is necessary whenever piping branches off, changes diameter, joins another type, or in the case of rigid pipe, whenever the direction changes. The shapes of fittings are common to all piping. The only difference is the way they are joined (connected).
PRO TIP: In most cases, when joining pipes with a fitting, the fitting and the pipe are made of the same materials. But this isn’t always the case. For example, a special precaution must be taken when joining copper pipes to steel. Wrap the threads of the copper fitting with plastic joint tape to prevent an electrochemical reaction that occurs between dissimilar metals, which can either erode the joint or cause the metals to permanently fuse.
4 Main Types of Pipe Fittings
There are many types of fittings for every kind of plumbing job. But they all four into one of these common categories of pipe fittings:
1. Branches and Turns
An “elbow” takes rigid piping around a curve. Various angles are available up to 90 degrees. A “T” provides a connector for a new branch at its base. And a “Y” fitting is a variation of the T; it’s usually found in drainage and vent lines to allow pipes from individual fixtures to be joined to one main stack.
2. Fittings for In-line Joints
When two pipes must be connected together in a strain run, a coupling (or sleeve) splices them. A nipple threaded on both ends extends a coupling for steel pipes. Ready-made nipples come in graduated sizes up to 12 inches long. A reducer attaches a length of small-diameter pipe to a larger one. Ts, Ys, and elbows are available with a reducer.
3. Transition Fittings
To connect one type of pipe material to another, a special fitting is needed to fasten both materials firmly and prevent the electrolytic action that can cause corrosion or fusion. This fitting is called a transition or dielectric fitting (or union). For example:
- The copper-steel fitting has one threaded end (to fit steel piping) and one smooth end to solder to copper pipe.
- The plastic-steel fitting has one threaded steel nut and a plastic insert to which a length of plastic pipe is glued. Because the plastic is electrically inert, the two materials don’t need to be separated.
- The plastic-copper fitting is similar but with a copper sweat fitting.
- Transition fittings are also available to join copper, steel, and plastic drain pipe to cast-iron pipe.
4. Drainage Fittings
The trap, one fitting used only in a drainage system, keeps a barrier of water in its U-turn to seal out odors from sewers.
All drainage fittings, whether threaded or not, have recessed joint surfaces. This is so that, when a pipe is inserted, the inner surface of both pipe and fitting is flush. This eliminates any possibility of waste material snagging in the joint and causing a blockage.
Since drain lines depend on gravity to pull waste through the system, the outlets of drainage pipe fittings angle downward.
Final Thoughts on Types of Pipe Fittings
There are so many types of pipe fittings that you could write a short book about them. Hopefully, this article will at least give you a better understanding of how they are categorized and used.
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- How to use compression fittings on copper pipes
- Here’s how to remove an old threaded pipe
- How to install a new threaded steel pipe
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- Here’s the quickest temporary fix for a pinhole leak
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- How to cut galvanized steel pipe
- Do hanging pipes need to be supported?
- How to prevent burst pipes (and make your pipes last longer)
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