reduce heat transfer from the furnace to the
water. A good part of the nontransferred heat is,
as you know, retained by the fireside or
waterside deposit. However, some of the heat
not properly carried away by the water and
not absorbed by the deposits remains with the
combustion gases. Therefore, [he temperature of
the stack gas rises.
When working in the watersides of a
boiler, you should take all possible precautions
to keep tools, nuts, bolts, cigarette lighters, and
other small objects from sliding down into the
tubes. Some required precautions are as follows:
1. Remove all small objects from your
pockets before entering the boiler.
2. Keep an inventory of all the tools and
equipment you take into the boiler. Ensure that
you remove each item and check it off the
inventory before closing up the boiler.
3. Do NOT set tools or other articles
down in places where you are likely to forget
them. For example, you must not leave tools on
top of the steam separators or in other places
that are easy to reach but hard to see.
4. When an article is lost in the boiler
watersides, you must NOT close up or operate
the boiler until the article has been located and
removed. Even a very small article can interfere
with boiler circulation and cause tube ruptures.
Additional precautions for waterside work
include the following:
1. Close, wire, and tag all steam, water,
and air valves that could possibly admit fluid to
the boiler. Disconnect (or otherwise render
inoperative) the remote operating valves as
2. Be sure that adequate ventilation is
provided before entering the waterside of a
3. Be sure that all portable extension lights
are of the watertight globe type, with the
globe encased in a rubberized, metal cage. Be
sure all lights are grounded and wires are not
broken. Examine the wires from end to end to
be sure that the insulation is not broken or
cracked, exposing the bare wire.
4. Station a person outside the drum whose
ONLY duty is to act as tender and to assist
personnel working in the drum.
Boiling out is a special waterside cleaning
technique. There are two approved methods
for boiling out boilersthe sodium metasilicate
pentahydrate method and the trisodium phosphate
method. The method used depends upon the
purpose of the boiling out. The sodium
metasilicate pentahydrate method is used to
remove rust-preventive compounds and other
preservatives; consequently, this method is used
for boiling out (1) newly erected boilers, (2)
reactivated boilers, and (3) boilers that have had
major tube renewals. The trisodium phosphate
method is used when you are boiling out for
the removal of oil and for scale softening in
preparation for mechanical cleaning.
LAYING UP IDLE BOILERS
Many operators faithfully and carefully
follow all the procedures and regulations
concerning boiler water treatment only to find
that the watersides, nevertheless, experience
corrosion and pitting. It should come as no great
surprise that the fault is not with the treatment
methods, but rather the manner in which the
boiler is permitted to stand idle. After the
pressure drops within an idle boiler, air gradually
seeps into the boiler, carrying oxygen with it.
The air also contains carbon dioxide that
combines with the boiler water to form
carbonic acid, which, in turn, lowers the
residual causticity of the boiler water. Gradual in-
leakage of feedwater can dilute and lower the
causticity of the boiler water even further. In
addition, condensation within the boiler, on both
waterside and firesides, can produce water
droplets that are saturated with oxygen and
contain no causticity. Conditions within the
boiler are now ideal for active and rapid corrosion.
The need for protecting boilers that are left idle
for any length of time should be obvious.