Chapter 4 Fittings

ObjectivesAfter completing this chapter, the student should be able to:identify and describe common types of fittings in a residential plumbing installation.understand that certain fitting materials and designs can only be used for specific systems.understand that some fitting materials can be used in all residential systems.relate fitting design selection to plumbing codes.order fittings based on installation requirements, size, and materials.

The most common offsets used in the plumbing industry are 90, 45, and 22-1/2. A 22-1/2 fitting is designed for a drainage waste and vent (DWV) system.90 and 45 fittings are used for most piping systems. Flexible tubing allows offsets to be created without fittings.Reference to the degree of a fitting is common when ordering fittings for most systems.When DWV cast iron fittings are ordered, the ordering process involves the percent of a circle a fitting represents.Degree of Fittings

Degree of Fittings

Fittings are offered with two basic connection types: fittings receiving pipe and fittings that are inserted into a hub.A fitting design known as a street fitting has one end that receives pipe and one end that is the same connection type as the pipe. Various Fitting Designs

Various Fitting DesignsNot all material types or fitting designs are offered in a street-fitting design.Some piping systems such as No-hub cast iron (NHCI) are not offered with a hub, and are therefore not considered a street design. Pressure-type plastic piping products that utilize a solvent weld (glue) joint have a deeper socket than a plastic DWV fitting.

Various Fitting Designs

Similarities of all offset fittings are the change of direction they achieve. A 90 fitting that is installed to create a perpendicular change in direction in a piping systemPressure systems, such as water and gas, use a short design pattern, and DWV use a longer radius design pattern. Offsets

Offsets

A fitting having three connections used for pressure systems is known as a tee. A tee is ordered stating the largest size side first and also stating the size of the run before the size of the branch. If all three sides are the same size, order the tee using the one size. When both sides of the run are the same size, order the tee using the single run size and the branch size. Tees

Tees

Common Tee Sizes and How to Order

A coupling is also known as a sleeve and connects two equal-sized pipe ends to form one continuous pipe. Except for SVCI (service weight cast iron) pipe, every piping system uses a coupling to connect two pipe ends. A coupling is not offered in a street design. Couplings

Couplings

A fitting designed to connect two different pipe sizes together is called a reducer.A reducing coupling and the fitting reducer are two different design styles.A fitting reducer is a street fitting, and the largest side is the street side, which inserts into a socket of another fitting to reduce a pipe size. A reducing tee is commonly created by inserting a fitting reducer into side 2 or side 3 of a tee.Reducers

Reducers

A bushing is a fitting design for connecting two different pipe sizes.Similar to a fitting reducer, except more compact.A bushing inserts into a fitting hub and receives a pipe end or street fitting. Not all types of piping systems use bushings.They are more common for threaded and plastic systems.Bushings

Bushings

It has external threads on one end and a socket connection on the other end.The threaded portion can connect to any material type compatible with National Pipe Thread (NPT) standards. A male adapter is manufactured to Iron Pipe Size (IPS) standards. Small sizes of copper male adapters are offered with a street end. Flexible tubing systems use male adapters that insert the unthreaded portion into the tubing, leaving the threaded portion exposed to screw into the desired location. Male Adapter

Male Adapter

It has internal threads on one end and a socket on the other end.A female adapter is the opposite of a male adapter relating to its threaded portion. The threaded portion can receive any material type that has external tapered threads compatible with National Pipe Thread (NPT) standards. A female adapter is manufactured to Iron Pipe Size (IPS) standards. Female Adapter

Female Adapter

It is a fitting designed to provide access directly within a piping system.Most codes dictate that unions remain accessible.Most gas codes dictate that a union cannot be installed in a ceiling. Various designs are available to connect similar and dissimilar materials. DWV systems utilize them for portions of a system that require sewage pumps. Unions

Unions

Water that is safe for human consumption is free from impurities and is known as potable water. No pipe, fitting, or product installed in a potable water system can consist of more than 8% lead.Flux and solder used to solder potable water systems cannot contain more than 2% lead. Some states, such as California require potable water systems to be 100% lead free.Water Distribution

Water Distribution Materials

Pipe TypeFitting Type(s)Connection TypePEXBrassCrimpedCPVCCPVCSolvent weldedCopperCopper and brassSolderedPolyethyleneNylon, brass, and galvanizedClampedGalvanizedGalvanizedThreadedBrassBrassThreaded

PEX is one of the most popular products installed for water distribution systems.The fittings have a unique ribbed pattern on the exterior to provide adequate holding capabilities once the fitting is installed. Two connection methods are used:The crimping method utilizes a fitting that is inserted into the tubing and is secured with a crimp ring.The expanding method utilizes a PEX ring that slides over the tubing, and an expander tool that is inserted into the tubing. PEX

PEX

The connection of the fittings and pipe are solvent welded (glued) with specially designed glue. CPVC glue cannot be used to solvent weld other types of plastics. Solvent-welded joints typically require 24 hours to cure before the system can be pressurized. CPVC

CPVC

Water distribution systems use three different grades of copper tube.The fittings for all three are the same.Copper DWV fittings have a greater radius and a shallow socket.Copper fittings are joined to copper tube with one of two welding processes: Soldering BrazingLess common processCopper

Copper

All PE fittings have a unique ribbed design, which is only compatible with PE. The fitting is inserted into the tubing and secured with a stainless steel hose clamp. Polyethylene

Polyethylene

Galvanized materials often produce rust when exposed to certain water qualities.That makes them a poor choice for water distribution systems.For this reason, brass materials are more widely used. Galvanized is commonly used to cap or plug pipe ends and to test piping systems because it is less expensive than brass.Brass fittings are used where poor water quality is present and galvanized materials will corrode.Brass fittings are available with chrome plating.Used when installed in finished locations.Galvanized and Brass

Galvanized and Brass

PVC used for water distribution is limited to installation on the exterior of a residential building.Typically terminates at a maximum of 5-0 inside the house.The flow radius of fittings are more compact than DWV, and the socket of a fitting is deeper.PVC adapters are only offered with plastic threads. PVC female adapters should not be screwed over metal male adapters.Prevents cracking or splitting of the PVC adapter.PVC

PVC

Drainage Waste and VentsDrainage waste and vent represents the combined drainage and vent systems. Many codes vary on the installation of a drainage system and vent system, but the material types can be the same for both systems. Fittings in the installation of a DWV system are designed to allow wastewater and sewage to flow with little resistance out of a drainage system by gravity.

DWV Fitting Materials

MaterialAbbreviationResidential UseDWV Polyvinyl ChlorideDWV PVCExtensively throughout USADWV Acrylonitrile Butadiene StyreneDWV ABSSome states in USANo-hub Cast IronNHCIVertical stacks for noise controlService Weight Cast IronSVCIRarelyGalvanizedGalv.RarelyDWV CopperType DWVRarely

WyeA wye has three connections and is named based on its similarity to the letter Y.The side outlet connection is known as a branch.The 45 branch creates a direction of flow to eliminate disturbance of wastewater within a DWV piping system.

Wye

ComboCombo is a trade name for a three-sided fitting that creates a long radius 90 branch (side inlet) that is perpendicular to the run.Manufactured to eliminate having to create a single fitting by combining a wye and 45.A cast iron 45 fitting is also known as a 1/8th bend, and a combo is commonly known as a combo wye and 1/8th bend. A combo is used extensively in the drainage system with the branch and run in the vertical or horizontal positions.

Combo

Sanitary TeeA sanitary tee is a compact fitting with three connections used in drainage and vent systems.The side connection known as the branch creates a standard radius that is a 90 angle from the run. The branch has a direction of flow to direct wastewater and sewage through a drainage system.Its use is strictly regulated by code pertaining to the installation positioning based on the flow direction.

Sanitary Tee

Sanitary CrossA sanitary cross has four connections with two as branches and has the same flow pattern as a sanitary tee.It is used to connect fixtures that are located side by side and back to back. Most codes limit the type of fixtures that can connect into the two branches, and a sanitary cross is regulated the same as a sanitary tee.

Twin ElbowA twin elbow has the same flow pattern as a sanitary tee, sanitary cross, and a standard 90 elbow.It is called a double 1/4 bend when ordering cast iron materials. Its name is derived from being two 90 fittings uniquely manufactured to connect back-to-back fixtures in a confined space.

Twin Elbow

Test TeeCannot receive discharge from the drain. Used to provide access for cleaning and is often referred to as the cleanout tee.A test tee has three connections.

Test Tee

CleanoutA cleanout is installed throughout a DWV system to provide access into the piping system for clearing obstructions.A cleanout is a female adapter and a threaded plug used together to create a single fitting. The plug is often called a cleanout cover. Codes dictate the installation locations and sizing of cleanouts. Plastic types are offered in a street-type design.

Cleanout

Closet BendIt is specifically used as the last fitting of a drainage system serving a toilet. The closet bend is a reducing 90 fitting. The 4 side of the closet bend can only be installed vertically with the 3 piping installed horizontally. A street version of this style is offered in plastic materials with the 4 size as the street side of the fitting and the 3 side having a hub.

Closet Bend

Heel Inlet 90A heel inlet 90 is a specialty DWV fitting and is referred to as a heel outlet fitting by a plumber.It can only be used in specific locations and is a DWV 90 with a branch located at the heel of the bend. The standard radius design is only offered as a 4 2, 3 2, and 3 1-1/2 size in plastic and 3 2 in no-hub cast iron. A long sweep version is available in plastic materials, but the sizing is limited to 3 2 and 3 1-1/2.

Heal Inlet 90

Closet FlangeA toilet is also known as a water closet, and the flange that connects the toilet to the drainage system is called a closet flange.PVC, ABS, and cast iron are materials commonly used to manufacture closet flanges. Most flanges have slots that allow adjustment of the closet bolts and also have fixed slot locations that do not allow adjustment of the closet bolts. A wax seal prevents harmful sewer gases from entering occupied areas and seals the connection between the toilet and the closet flange.

Closet Flange

P-TrapEvery fixture must be served with a protective water seal to prevent harmful sewer gas from entering an occupied space. A p-trap gets its name from its appearance, which resembles the letter P, and is installed receiving the outlet flow of water from a fixture.P-traps are available in a variety of styles, which include one-piece and two-piece designs.

P-Trap

Trap AdaptorA slip-joint p-trap is tubular size and has a smaller outside diameter as the connecting DWV pipe. The fitting for connecting tubular sizes to DWV pipe sizes is known as a trap adapter; also referred to as a desanco. A trap adapter is typically installed at the fixture installation phase of a project. Cast iron, copper, and galvanized piping systems use a brass trap adapter.

Trap Adapter

PVCOne of the most widely used products for DWV installation. PVC fittings are made from the same materials as the pipe.All DWV fittings are identified on the side as DWV PVC designs.

ABSABS is black and easily distinguished from white PVC.ABS fitting designs and code regulations are the same as those for PVC.Connections must be made with approved adapters.Most codes require the use of glue specifically designed for ABS.

Cast IronCast iron fittings are more expensive and take longer to install.DWV fittings must comply with all the same code regulations as for other DWV material types.Generally used in commercial, as opposed to residential, plumbing.

Corrugated Stainless Steel Tubing FittingsUsed for gas distribution systems.Uses unique self-flaring fittings not compatible and not interchangeable with other tubing.Traditional fitting designs, such as male adapters, couplings, and tees are used with CSST.

CSST Fitting Connection

SummaryMost fittings are manufactured with the same material as the connecting pipe.Brass fittings can be interchangeable with numerous piping materials.Threaded fittings can be used to connect different material types.Plumbing codes dictate that solvent-welded fittings can only be used with compatible pipe.

SummaryPEX fittings are specifically designed for the type of PEX connections utilized.Cast iron fittings are specifically designed for either NH or SV pipe.Dissimilar metal connections can cause corrosion and must be protected against electrolysis.DWV fittings have a flow pattern and plumbing codes dictate their use.DWV fittings are not designed for use with pressure piping systems.

SummaryWater piping fittings have more compact design than DWV fittings.Black steel fittings cannot be installed in a potable water system.A male adapter has external threads and a female adapter has internal threads.A street fitting design has one end that is the same outside diameter as the connecting pipe.A fitting socket is also known as the hub.