CHA.PTER2
The above procedure
may
be
omitted
in
the
case
of a unit previously used or known
to
be
internal-
ly
clean. However, consideration must
be
given
to the possibility
of
contaminating materials
entering
the
boiler from
the
system.
On
a steam system, the condensate should be
wasted until tests show
the
elimination
of
un-
desirable impurities. During
the
period that con-
densate
is
wasted, attention must
be
given to the
treatment
of
the raw water used
as
make-up so
than
an
accumulation
of
unwanted materials or
corrosion does not occur.
On
a hot water
system.,
chemical cleaning
is
generally necessary and
the
entire system should
be
drained after treatment. Consult your Qeaver-
Brooks local representative for recommenda-
tions, cleaning compounds, and application
procedures.
G.
WASHING
OUT
1.
Hot Water Boiler
In
theory,
a·
hot water system
and
boiler that have
been
initially cleaned, filled with
raw
water (and
that water treated), and with
no
make-up water
added, will require
no
further cleaning or treat-
ment.
However, since
the
system (new or old)
may
allow entrance
of
air
and
unnoticed or un-
detected leakage
of
water, introductions
of
raw
water make-up or air
may
lead
to
pitting, cor-
rosion
and
fonnation
of
sludge, sediment, scale,
etc., on the pressure vessel
watexside.
If
the
operator
is
absolutely certain that the sys-
tem
is
tight, then
an
annual waterside inspection
may
be
sufficient.
If there
is
any
doubt, then
the
pressure vessel
watexside
should
be
inspected
no
later than three
months after initially placing
the
boiler into
operation
and
periodically thereafter
as
indicated
by
conditions observed during inspections.
THE
PRESSURE VESSEL
2.
Steam Boiler
No
later
than
three months after initially placing
the
boiler into operation and starting service, and
thereafter
as
conditions warrant, the pressure
vessel should
be drained after being properly
cooled
to
near ambient temperature, handhole
covers removed, and waterside surfaces
in-
spected for corrosion, pitting, or formation of
deposits.
Flushing
of
Pressure Vessel
Interior
Upon
completion
of
inspection, the pressure ves-
sel
interior should be flushed out
as
required with
a high pressure hose.
If
deposits are not fully
removed
by
flushing,
this
may
require immediate
consultation with your Cleaver-Brooks local
rep-
resentative
and
in
extreme cases,
it
may
be
neces-
sary
to
resort
to
acid cleaning. Professional
advice
is
recommended if acid cleaning
is
re-
quired.
These inspections will indicate
the
effectiveness
of
the
feedwater treatment. The effectiveness
of
treatment,
the
water conditions,
and
the
amount
of fresh water make-up required are
all
factors
to
be
considered
in
esta~lishing
the
frequency
of
pressure vessel washouts. Contact your Cleaver·
Brooks local representative for more infonna-
tion.
H.
SLOWDOWN
STEAM
BOILER
Boiler water blowdown
is
the
removal
of
some
of
the
concentrated water from
the
pressure ves-
sel
and
its replacement with feedwater
so
that a
lowering
of
the
concentration
of
solids
in
the
boiler water occurs.
Solids are brought
in
by
the
feedwater even
though
this
water
is
treated prior
to
use
through
external
processes that are designed.
to
remove
unwanted substances that contribute
to
scale
and
deposit formations. However, none of these
are
in
themselves capable
of
removing
all
substances
and
regardless
of
their efficiency, some solids
will
be
present
in
the
boiler feedwater.
750-150
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