of Pipe Fittings
What are pipe fittings?
Pipe fittings basically include the range of components that are used
to connect pipe ends for in-line, multi-port, offset and mounting
configurations. Pipe fitting cross sections are mostly, but not always,
circular in shape to match with the pipe section with which they are
connected. Pipes can be metallic or plastic and pipe fittings vary
depending on the type of pipe used.
Pipe fittings are used for various purposes. They can be used to extend
or terminate pipe runs, change a pipe's direction, to connect two or
more pipes and to change the pipe size.
Pipe fittings are used with equal importance in pressurized
applications and non-pressure applications like drain, waste, and vent
(DWV) systems. Pipe fitting also finds application in plumbing, HVAC
(High Voltage Alternating Current), manufacturing, etc. Pipes are
primarily meant for transporting various solids and fluids, and hence,
pipes and pipe fittings are constructed from a wide range of materials.
In fact, the materials used for making pipe fittings depend much on
- Size is the most important parameter that should be
considered while buying pipe fittings. There are various options
available for size of pipe fittings like:
The selection for size should be considered only for fittings
that match with the pipe type adhering to the specific ANSI schedule
number. However, there are many pipe fittings that does not possess
an ANSI number.
- Standard English sizes: These sizes range from 1/8
to greater than 36 .
- Metric sizes: Popular metric sizes range from less
than 10 mm to greater than 1000 mm.
- Schedule: The "schedule numbers" are
assigned by the American National Standards Institute (ANSI) in
order to classify the thickness of walls for use with different
pressure. ANSI schedule numbers include all pipe and fitting
sizes from NPS 1/8 through NPS 36, which are classified as
Standard (STD), Extra Strong (XS) and Double Extra Strong (XXS)
and all wall thicknesses by ANSI schedule number.
- Shape of fittings is another important parameter the
buyer's should consider while selecting pipe fittings. The popular
shapes available for pipe fittings include oval, round, square and
rectangular. However, the round or circular shape is the most
- Material: The type of material used for making pipe
fittings is also very important. Construction and material
specifications of pipe fittings are application-dependent.
Optimization of component selection largely requires consultation of
the users with the fitting suppliers. Actually a wide range of
materials are used for making pipe fittings. The buyer's are often
confused judging the right material for fittings. The most common
materials used include aluminum, carbon or graphite, ABS
(Acrylonitrile Butadiene Styrene), CPVC (Chlorinated Polyvinyl
Chloride), brass, bronze, ceramic or ceramic lined, polyvinyl
chloride (PVC), stainless steel, carbon and alloy steel, concrete,
EPDM, clay or vitrified clay, fiberglass or composite, fluororesin
(PFA), glass or glass lined, rubber or elastomer, gray or cast iron,
ductile iron, lead, neoprene, nylon or polyamide, polyethylene (PE),
polypropylene (PP), PTFE or PTFE lined, titanium, and zirconium.
- Pipe Fitting End: Buyers are often confused while
selecting pipe fitting ends. Proper selection for pipe fitting end
is very essential for proper flow of the material. The ends of pipe
fittings are built slightly larger than in such a manner so that the
connections can easily fit in without narrowing the inner diameter
(ID) of the pipe. This keeps flow consistent. The most common
fitting ends available are:
- Male pipe thread
- Female pipe thread
- Plain end bell or socket
- Flare or flange
- Male straight thread
- Female straight thread
- Compression fitting
- Pipe clamp end
- Barb or rib
- Connector types: While selecting pipe fittings, the buyer
should make sure that a fitting can have two different connector
types -- threaded or slip, male or female. One end of the fitting
might be male threaded and the other female threaded. Metal pipes
are usually threaded, while plastic pipe can be threaded or slip
fit. Generally, threaded pipes screw together to connect, while slip
fit pipes make use of sleeves that slip into one another. Pipe
fittings are kept in place by male and female connectors like:
- Male threaded: In this case, threads are exterior and
are designed to screw into the inside of a larger diameter pipe
end with internal threading.
- Female threaded: Here the threads are interior,
designed to receive male threaded pipe fittings.
- Male slip fit: In this case, there are no threads,
and the fittings are designed to slip into a female sleeve,
slightly larger in size.
- Female slip fit: There are no threads, and are made
to receive a narrower male slip fit.
- Features: Fittings enable pipe to be installed and joined
where necessary and terminated in the appropriate place. A buyer
should also consider the features of pipe fittings before selecting
them. Each kind of pipe has its own specification and requires its
own type of fitting, but all fittings share some common features
- Pipe fittings are either male or female, which is related to
the proper positioning at the connecting points.
- Pipes, nipples and male fittings usually insert into female
fittings. In threaded fittings, male threads are on the outside
and female threads are on the inside. Fittings that have one
male end and one female end are called street fittings.
- While measuring the size of fittings, male threaded fittings
are measured OD or to the outside edge, while female fittings
are measured ID, or to the inside edge of the inlet.
- The two standard sizes for pipe fittings are IPS (Iron Pipe
Size) or CTS (Copper Tube Size). These two standards are
incompatible and connected by means of adapters. Male IPS
fittings are referred as "MIP" and female IPS fittings
are referred as "FIP".
- Pipe fittings should also be chosen on the basis of the inner and
outer diameter of the pipe so that they easily fit the pipe. Pipe
fittings can also be plated, lined, insulated and underground rated
and therefore selecting the right one is very important.