Fittings are used to change the direction of flow in a system. Almost any kind of pipe assembly is possible with the wide variety of pipe fittings made today. Plumbing codes require that different type of fittings be used in different types of plumbing systems.
The next few slides present four types of cast-iron fittings used by plumbers: bends, branches, increasers, traps.
Bends are fittings that change the direction of piping. Bend dimensions are expressed as fractions of a complete circle.
A circle contains 360 degrees. To determine the number of degrees a given bend turns, multiply the fraction by 360 degrees.
For example, a 1/8 bend turns the pipe 1/8 X 360 degrees, or 45 degrees.
Bends are available in most standard pipe sizes, the smallest being 1 ½ inches in diameter.
Long bends are similar to standard bends except for one feature: long bends consist of one leg that is longer than the other.
Long Bend Sizing
Long bends are typically sized with a two-number system. The first number indicates the diameter of the bend; the second number indicates the length of the longer leg of the fitting.
The heel inlet allows small vents or drains of smaller sizes to be connected from the right or left side of the bend. Fittings with side inlets are called either right-hand or left-hand fittings, depending on where the opening appears.
Closet bends connect the water closet to the main drainage piping. They are available with left-hand or right-hand or right-hand side openings. Closet bends have a reduction in the direction of flow.
A variety of fittings allow you to connect pipes to one another to create branches in the piping system.
Click on each type of cast-iron branch to know more:
Wyes and double wyes are fittings used to join two or three drains into one pipe. Wyes are used to make a 45-degree direction change in horizontal drain and waste pipes when connecting to the building main drain.
Double wyes perform the same function except that they have openings for two branch lines.
The sanitary tee connects pipes at right-angle intersections in branches that run from horizontal to vertical. Model building codes restrict the use of sanitary tees to sanitary drainage systems where the flow of materials is from the horizontal to the vertical runs.
Double Sanitary Tees
The double sanitary tee, also called a sanitary cross, connects two branch lines entering the system from opposite directions. This fitting allows a plumber to place the horizontal runs and vertical runs centrally.
An increaser is a fitting that connects two pipes of different diameters. It is used to increase the size of a straight-through line of pipe.
Increasers are commonly used to connect a larger pipe to the top of a vent stack. This provides for a larger-sized pipe above the heated area of a building. This process, in turn, keeps frost buildup from closing the opening in the vent stack.
Traps are fittings designed to provide a liquid seal that prevents sewer gas from escaping into a building.
Traps are installed between the drainage line and fixtures or drains.
Many traps are designed with cleanout plugs that can be removed to clean out the trap.
Common traps include P-traps and S-traps. P-traps are commonly used for sinks and lavatories. S-traps are no longer installed but are still found in older buildings.