rings in the two outer grooves of the coupling are
compressed to seal the joint tightly. The T-shaped
center ring forms a seal between the pipe ends to
eliminate jogs and pockets and to provide for
uninterrupted flow. In this type of joint, you have a
tight and flexible connection.
A joint like the one shown in the figure can be
assembled entirely by hand. After making sure the
rings in the grooves of the coupling are in correct
position, use the following two-step procedure, shown
in figure 3-64, to make the connection.
1. Apply a thorough coating of lubricant to the
male end of the pipe, all the way around (view A, fig.
3-64). If a special lubricant supplied by the manu-
facturer is not available, prepare a jellylike soap
2. Pull or push the pipe together, as shown in view
B of figure 3-64, and the joint is complete.
Ductile Iron Pipe
Ductile iron is cast iron in which the carbon is
reformed by magnesium inoculation. This results in
exceptional strength characteristics without otherwise
Figure 3-64.Steps in assembling a cement-asbestos pipe
changing the basic nature of the cast iron. Because of
this treatment, ductile iron has exceptional strength
with good machinability, high impact, corrosion
resistance, and great beam strength. For these reasons,
ductile iron pipe is ideal for transportation of water.
When laying this pipe, you should ensure that both
the bell and plain ends are clean. This is to prevent
leaking joints. Sand, dirt, excess coating, ice, and other
foreign material should be removed carefully from the
plain end and the interior of the bell. This ensures
proper seating of the gasket and correct entry of the
plain end into the bell socket. The direction of the bells
is not related to the direction of water flow within the
The mechanical joint for ductile iron pipe has
four parts: a flange cast integrally with the bell of the
pipe; a rubber gasket fitting a recess in the socket; a
gland, or follower ring, to compress the gasket; and
bolts and nuts for tightening the joint. The assembly
of the joint is simple and requires only a wrench to
tighten the nuts.
If the pipe must be cut, it may be cut with an
abrasive wheel, a rotary wheel cutter, a guillotine pipe
saw, a milling wheel saw, or an oxyacetylene torch. Of
these cutting tools, the abrasive wheel saw is used most
often for out-of-trench cuts; while the oxyacetylene
torch method is used in trench cuts. Cut ends and rough
edges should be ground smooth. For push-on type
connections, the cut end should be beveled slightly.
Because of the high-impact strength of ductile
iron, you only need to remove rocks and boulders 8
inches or greater in diameter from the material to be
used as backfill.
An extremely dry mix of cement, sand, gravel,
and water with or without additives is used and cast
in steel forms to manufacture concrete pipe.
Concrete pipe can be reinforced with welded wire
fabric or rebar. It is normally a flared bell-and-
spigot-type pipe, similar to cast-iron soil pipe, but in
larger sizes, 10 inches and above. The bell and spigot
have a smooth configuration.
FITTINGS. The fittings are the same as cast-
iron and vitrified clay pipe, using a flared bell-and-
spigot joint, or a smooth bell and spigot. This joint is
called the slip joint.
CUTTING.A portable concrete saw is used to
cut concrete pipe reinforced with steel. When cutting