Understanding Fittings, Angles, and Appurtenances

Pressure pipe fittings serve two purposes. The first, like structures in gravity systems, is to enable two or more pipes to connect together. For example, a tee or wye fitting provides a connection for three pipes, while a crossing fitting provides a connection for four. The second purpose of a fitting is to create a bend in the direction of the pipeline, the angle of which is typically dictated by manufacturing standards. For example, elbows are commonly available in 90-degree, 45-degree, 22.5-degree, and 11.25-degree versions. For this reason, bend angles are a big part of pressure pipe design.

In addition to bend angles, a slight amount of deflection is also allowed within connections. This deflection angle varies depending on how the pipes or fittings have been manufactured and is also part of the design. This allowable deflection also enables a series of pipes to form a curve by providing a little deflection at each joint. Therefore, pressure pipes can be laid out on a curve with the radius determined by the allowable deflection.

Another factor that can be incorporated into the design is the allowable bending radius of the pipes. Bending the pipes is another way that a system can be laid out along a curve. The allowable bending radius is a function of the size, material, and manufacturer specifications of the pipe.

Because of available fittings, allowable deflection angles, and allowable bend radius, each bend in a pressure pipe is a design in itself. As a designer, you will be required to choose the right combination of fitting, deflection angle, and bend radius to make each bend in the pipeline.

Appurtenances are another component of pressure pipe designs. The challenge with appurtenances is that they usually require consideration for human access. For example, a fire hydrant must be properly located at ground level so that firefighters or maintenance personnel can access it.

Understanding Pressure Pipe Networks