The initial cost of the HRT boiler is relatively low
and installing it is not too difficult. The boiler setting can
be readily changed to meet different fuel
requirementscoal, oil, wood, or gas. Tube replacement
is also a comparatively easy task since all tubes in the
HRT boiler are the same in size, length, and diameter.
The gas flows in the HRT boiler from the firebox to
the rear of the boiler. It then returns through the tubes to
the front where it is discharged to the breaching and out
The HRT boiler has a pitch of 1 to 2 inches to the rear
to allow sediment to settle toward the rear near the bottom
The fusible plug is located 2
inches above the top row of tubes. Boilers over 40 inches
in diameter require a manhole in the upperpart of the
shell. Those over 48 inches in diameter must have a
manhole in the lower, as well as in the upper, part of the
shell. Do not fail to familiarize yourself with the location
of these and other essential parts of the HRT boiler. The
knowledge you acquire will definitely help in the
performance of your duties with boilers.
Another type of fire-tube boiler is the FIREBOX
boiler that is usually used for stationary purposes. A split
section of a small firebox boiler is shown in figure 1-5.
Gases in the firebox boiler make two passes through the
tubes. Firebox boilers require no setting except possibly
an ash pit for coal fuel. As a result, they can be quickly
installed and placed in service. Gases travel from the
firebox through a group of tubes to a reversing chamber.
They return through a second set of tubes to the flue
connection on the front of the boiler and are then
discharged up the stack.
What are the two types of boilers?
What are the four types office-tube boilers?
What is the primary factor that allows the firebox
boiler to be quickly installed and placed into
BOILER FITTINGS AND ACCESSORIES
Describe the function and
operation of the different types of boiler fittings and
Now that the basic structure of a boiler has been
explained, boiler fittings (fig. 1-6) and the operation or
function of various devices, such as controls, valves, and
try cocks, must be presented. A sufficient number of
essential boiler fittings and accessories are discussed in
this section to provide a background for further study. As
a reminder, and in case you should run across some unit
Figure 1-5.Split section of a small firebox boiler.