Figure 3-2.A typical manhole for distribution system.
house the necessary valves, traps, and expansion joints.
A typical manhole is shown in figure 3-2.
The utilidors, or tunnels, of the utilidor type of
system are constructed of brick or concrete. The size
and shape of the utilidor usually depend upon the
number of distribution pipes to be accommodated and
the depth the utilidor must go into the ground.
Manholes, sometimes doors, are installed to provide
access to the utilidor (tunnel). A typical utilidor is
shown in figure 3-3. The utilidor is usually constructed
so the steam and condensate return lines can be laid
along one side of the tunnel on pipe hangers or anchors.
This is usually done with the type of hanger with rollers
that provides for free movement required by the
expansion of the pipe. The other side of the utilidor
should be a walkway that provides easy access to lines
when you are inspecting and doing maintenance.
Figure 3-3.A typical utilidor.
Aboveground steam distribution systems are
further divided into overhead and surface systems:
Overhead Distribution Systems
Overhead distribution systems are often used in
temporary installations; however, they are sometimes
used in permanent installations. The main drawback to
this type of distribution system is the high cost of
maintaining it. These overhead systems are similar in
many respects to underground distribution systems.
They require valves, traps, provision for pipe
expansion, and insulated pipes. The main difference is
that the steam distribution and condensate return piping
are supported on pipe hangers from poles, as shown in
figure 3-4, instead of being buried underground.
Surface Distribution Systems
In some cases, you will find that steam and
condensate lines are laid in a conduit along the surface
of the ground. These systems, however, are not as
common as overhead and underground systems.
Surface systems require about the same components as
the overhead and the underground systemstraps,
valves, pipe hangers to hold the pipes in place, and
provision for pipe expansion. Sometimes an expansion
loop, formed by a loop of pipe, is used instead of an
expansion joint to provide for pipe expansion.
The maintenance required for exterior distribution
systems normally consists of inspecting, repairing, and
replacing insulation, traps, valves, pipe hangers,
expansion joints, conduit, utilidors, and aluminum or
Figure 3-4.Steam and condensate lines supported by poles.