CHAPTER2
(3) Prevention
of
intercrystalline crack-
ing
or
caustic embrittlement
of
the boiler
metal.
·
( 4) Prevention
of
carryover and foaming.
The accomplishment
of
these objectives general-
ly
requires proper feed water treatment before and
after introduction
of
water into the boiler. The
selection
of
pre-treatment processes depends
upon the water source,
its
chemical charac-
teristics, amount
of
makeup water needed, plant
operating practices, etc. These treating methods
include filtering, softening, de-mineralizing,
deaerating, and pre-heating. After-treatment
in-
volves chemical treatment
of
the boiler water.
Because
of
the variables involved, no one "boiler
compound" can be considered a
"cure-all" nor
is
it advisable to experiment with homemade treat-
ing methods. Sound recommendations and their
employment should be augmented
by
a periodic
analysis
of
the feed water, boiler water, and con-
densate.
The internal
or
waterside surfaces
of
the pressure
vessel should
be
inspected with sufficient fre-
quency
to
determine the presence
of
any con-
tamination, accumulations
of
foreign matter,
of
corrosion and/or pitting.
If
these conditions are
detected, contact your Cleaver-Brooks local rep-
resentative for advice on corrective action.
It
is
recommended that a properly sized water
meter be installed in the raw water make-up line
to accurately determine the amount
of
raw water
admitted
to
the boiler (steam
or
hot water)
to
aid
the water treatment program
in
maintaining
proper waterside conditions.
The general feeling exists that a hot water boiler
does not require water treatment, but this
is
a
false
assumption.
Even
though
these units
generally operate on closed systems and
blow-
down
is
seldom practiced, the need remains to be
alert
to
system water losses and a water meter
is
recommended for water make-up lines.
750-150
THE
PRESSURE VESSEL
E.
CLEANING
Hot
Water
and
Steam Piping
Steam
and water piping systems connected to the
boiler may contain oil, grease
or
foreign matter.
These impurities must be removed
to
prevent
damage to
pressure vessel heating surfaces. On a
steam system, the condensate should be wasted
until
tests show the elimination
of
undesirable
impurities. During the period that condensate
is
wasted, attention must be given
to
the treatment
of
the raw water
used
as make-up so that an
accumulation
of
unwanted materials
or
corrosion
does not occur. For more information, contact
your local Cleaver-Brooks representative.
On
a hot water system, chemical cleaning
is
generally necessary.and the entire system should
be
drained after treatment Consult your local
Oeaver-Brooks representative for recommenda-
tions, cleaning compounds, and application
pro-
cedures.
Pressure Vessel ·
The waterside
of
the pressure vessel must be kept
clean from grease, sludge and foreign material.
Such deposits,
if
present, will not only shorten
the life
of
the pressure vessel and interfere with
efficient operation and functioning
of
control or
safety devices, but might quite possibly cause
unnecessary and expensive re-work, repairs and
down-time.
The installation and operating conditions that the
boiler will
be
subjected
to
should be considered
and cleaning
of
the waterside
of
the pressure
vessel should be provided during the course
of
initial start-up.
The pressure vessel and the steam and return
lines
or
hot water piping represent, in effect, a
closed system. Although the steam and return
(condensate) lines or the hot water piping
system
may have
been
previously cleaned,
it
is
possible
that:
(1) Cleaning has been inadequate.
CHAPTER 2·7
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