Types of Pipe Fittings Used in Plumbing Systems

Pipe fittings are used to connect pipes of same size or different sizes; they regulate or divert the flow of liquid in it. There are various types of pipe fittings used in plumbing system serving its purpose.

The material of the fittings should be compatible to the pipe material, nature of liquid flowing, pressure and temperature both inside and outside of the pipe; generally they are available in brass or copper. The different types of pipe fittings used are explained below.

Types of Pipes Fittings used in Plumbing System

1. Elbow (45 Deg and 90 Deg)

An elbow is generally used to change the direction of flow of liquid between two pipes. If the two pipes are of different diameters then the elbow is called as a reducer.

Elbows are available in two angles, 90 degree elbow and 45 degree elbow. Elbows are usually threaded to the pipes (female threads*) or else they are welded.

Elbows 90 degree and 45 degree

2. reducer

As already mentioned reducers are used to connect two pipes of varying diameters, their main purpose is to regulate the flow (slowdown in most cases). The reducers can be of two types

  • Concentric reducer: It is a cone shaped reducer; in this type of reducers there is a risk of air accumulation which in turn will increase the pressure on the pipe.
  • Eccentric reducer: It is a reducer with one side parallel; since only one side is curved the risk of air accumulation is eliminated in this type of fittings.

3. Coupling

Couplings also connect two pipes in a straight line. The two pipes connected by a coupling should be of same diameter. They are soldered, welded or glued to the pipe ends to be connected.

Couplings are used when a long plumbing line is to be laid and one pipe length is not sufficient, but mainly couplings are used when leakages occur in the pipeline. They are of two type compression coupling and slip coupling.

4. Union

Union is a fitting that serves similar purpose of that of a coupling, only difference is that the couplings are fixed and cannot be removed after installation, but unions are usually threaded to the pipes and can be removed if necessary. In some unions one end is male threaded** and one end is female threaded*

Coupling and Union

5. Tee

A tee fitting is used to connect three pipes either of same or different diameters. They serve the purpose of distributing the flow from one pipe to two other pipes in different directions usually. Sometimes flow from two pipes is combined to flow in the third pipe. In other words tee serves for one inlet with two outlets or two inlets with one outlet. Tee fittings are available in perpendicular or inclined directions.

Inclined and Perpendicular TEE

6. Cross

A cross fitting is used to connect four pipelines together. Since the number of pipes connected is more this joint will be subjected to more stress thus cross fittings are to be made strong and durable to resist them. They are usually used in fire sprinkling systems when large amount of water is required in all directions since it can serve three outlets with one inlet.

Brass Cros Fitting

7. Plug & Cap

A plug and a cap are used to stop the flow in the pipe that is to close the pipe during repair works. They both serve the same purpose but the difference is in their structure, the plug is provided with male threads** while the cap is provided with female threads*.

Plug and Cap

8. Adapters

When the ends of the pipes are not suitable to insert any pipe fittings or it is not desirably flat then adapters are used to make the ends flat. Adapters can be male threaded or female threaded in one end based on the purpose. The other end of the adapter is plain so it is welded or glued to the pipe ends.


9. Nipple

This is a type of pipe fitting which is used to connect two other pipe fittings in place. It usually contains male threads throughout its length.

10. Barb

Brabs are fittings used when a flexible hose is the connected to the pipe line.

Nipple & Brab

11. olets

If the pipe dimensions are not suitable enough to use any pipe fittings (e.g. if the diameter of the pipe is too large when compared to the fittings diameter available) then we use olets to insert the pipe fitting properly. There are many types of olets available some are shown below


**male thread: if the threads in a fitting are given on the outer surface it is called male threaded.

*female thread: if the threads in a fitting are given in the inner surface it is called female threaded.