A threaded coupler is a device designed for joining various types of threaded parts to one another. While there are several different types of couplers an individual can choose from, most couplers are designed for specific applications. For example, some couplers are designed to join threaded rods together, while others are only intended for joining lengths of pipe. The primary difference between couplers for rods and those meant for pipes is what is known as the thread pitch. Pipe threads are slightly different than those found on nuts and bolts, so a threaded pipe coupler cannot replace a rod coupler, and vice versa.
The primary purpose of a threaded coupler is to connect two sections of pipe, rod, or tube together using threads. Normally, couplers have what are known as internal threads. It may be easier to understand this idea when thinking about the cap on some types of milk jug or other plastic beverage bottles as examples of basic threaded couplers. The threads inside the cap are internal, and the threads on the jug are external. Similarly, a short length of pipe with internal threads at both ends may serve as a coupler.
Depending on the intended application, a threaded coupler can possess two internal or two external threads, or an internal thread on one end and external on the other. For example, some threaded rod couplers are designed to add a designated length to a threaded rod. In this case, one end is internally threaded, to allow an individual to screw a length of rod onto one end while external threads exist at the other end.
Another common use for some types of threaded couplers is to make adaptations from one size to another. This type of coupler is common in plumbing applications. For instance, some plumbing connections or fixtures require different sizes than the existing pipe sizes leading into the connection. Instead of replacing part of the system, a threaded coupler can be used to connect a smaller pipe to a larger one.
Threaded couplers are usually constructed from several different types of metal, although some are made from polyvinyl chloride (PVC) and specifically designed for use with that type of plumbing application. Additionally, threaded couplers are available in almost any size one would need. A threaded coupler is the fastest method for joining two lengths of pipes, as long as pipes have at least one threaded end. These joining pieces are an ideal solution for most threaded connections.