Pipes are components of a pipe network that primarily represent pipes but can be used to represent any type of conduit such as culverts, gas lines, or utility cables. They can be straight or curved, and although primarily used to represent gravity systems, they can be adapted and customized to represent pressure and other types of systems such as water networks and force mains. The standard catalog has pipe shapes that are circular, elliptical, egg-shaped, and rectangular and are made of materials that include PVC, RCP, DI, and HDPE. You can use Part Builder (discussed earlier this chapter) to create your own shapes and materials if the default shapes and dimensions can’t be adapted for your design.
Structures are the components of a pipe network that represent manholes, catch basins, inlets, joints, and any other type of junction between two pipes. The standard catalog includes inlets, outlets, junction structures with frames (such as manholes with lids or catch basins with grates), and junction structures without frames (such as simple cylinders and rectangles). Again, you can use Part Builder to create your own shapes and materials if needed.
Null structures are created automatically when two pipes are joined together without a structure; they act as a placeholder for a pipe endpoint. They have special properties, such as allowing pipe cleanup at pipe intersections. Most of the time, you’ll create a style for them that doesn’t plot or is invisible for plotting purposes.