Plastic pipe fittings have become very popular these days for water
supply and drain lines. The low cost, good durability and easy
installation has made plastic pipes most popular.
Fittings meant for plastic pipes and for connecting plastic to metal
pipes are available in various options like threaded, compression and
solvent weldable types. The diameter and specification of plastic pipe
fittings also vary depending on their application. For example, fittings
with smaller diameters are used for pressure connections and they are
slightly heavier and have deeper throats.
Threaded plastic fittings thread almost like metal fittings. When both
hot and cold water are to be carried, it is advised to install special
transition fittings in order to prevent leaks caused by the different
expansion rates of plastic and metals. In fact, plastic pipe fittings
are available for almost every kind of application.
Types of Plastic Used:
- Buyer's should always check that plastic pipe fittings are
rated by the American Society for Testing and Materials (ASTM).
- Pipe fittings designed for water supply pipes should carry
the National Sanitation Foundation's approval certifying that
the fittings are suitable for carrying drinking or potable
- The size and steel of the fittings should also be checked so
that they fit the right kind of pipe.
- The type of plastic used for making fittings should be
confirmed so that they fit a particular application.
Various grades of plastic are used for making pipe fittings. Popular
plastic types used are:
- PVC and CPVC: PVC or poly-vinyl-chloride is the most
popular material used for making plastic pipe fittings. These
fittings are rigid and are connected by thread or solvent weld
(glue) connections. PVC pipes come in different pressure ratings and
fittings should be chosen accordingly. Standard PVC pipes and
fittings are used only for cold water supply and drain line.
- Another variety of PVC called CPVC is ideal for use with hot
water supply lines.
- ABS: (Acrylonitrile butadiene styrene) is another variety
of plastic widely used for making plastic pipe fittings. ABS can be
easily recognized by its black color and rigidity. ABS fittings are
usually used for drainage lines and are more economical than PVC
- Polyethylene: Also known as PE, polyethylene pipe is
mostly preferred for hot and cold water supply lines. Polyethylene
is generally black or gray in color and is semi-flexible. These
pipes are often connected using barb-fittings with clamp rings.
However, these fittings can also be heat-fused using an appropriate
tool. Polyethylene is mostly used for supply line for lawn sprinkler
system, underground loops in geothermal heating, etc.
- Nylon: Nylon is highly resistant to chemical reactions.
Because of this fact, nylon is the most popular choice for making
pipes used in water lines, and other pipe lines that carry flammable
fluids and solvents.