Cleaver-Brooks CBH 40 - Periodic Inspection; Preparation for Extended Lay-Up

actual water analysis. Lowering the water in the
gage glass approximately 1/2" is often acceptable
as a guide to adequate blow, however, this should
not be interpreted as a rule since water analysis
procedures should prevail. If the glass cannot be
viewed by the party operating the valve, another
operator should watch the glass and direct the
valve operator.
Close the downstream (slow opening) valve first
and a fast as possible. Then close the valve next to
the boiler. Slightly crack the downstream valve
and then close it tightly.
Under no circumstances should a blow-off valve be
left open and the operator should never leave until
the blowdown operation is completed and valves
closed.
I. PERIODIC INSPECTION
Insurance regulations or local laws will require a
periodic inspection of the pressure vessel by an
authorized inspector. Sufficient notice is generally
given to permit removal of the boiler from service
and preparation for inspection.
When shutting down, the load should be reduced
gradually and the pressure vessel cooled at a rate
that avoids damaging temperature differential
that can cause harmful stresses. Vessels should not
normally be drained until all pressure is relieved -
again to prevent uneven contraction and tempera-
ture differentials that can cause expanded tubes to
leak. Draining the unit too quickly may cause the
baking of deposits that may be present on the
heating surfaces. Some heat, however, may be
desirable to dry out the interior of the boiler.
If the internal inspection is being made at the
request of an authorized inspector, it is well to
learn from him whether he desires to observe the
conditions prior to cleaning or flushing of water-
side surfaces.
Be certain that a supply of manhole and handhole
gaskets is available along with any other gaskets
or items needed to place the unit back into
operation after inspection.
Have available information on the boiler design,
dimensions, generating capacity, operating
pressure or temperature, time in service, defects
found previously and any repairs or modifications.
Also have available for reference records of
previous inspections.
Be prepared to perform any testing required by the
inspector including hydrostatic.
After proper cooling and draining of vessel, flush
out the waterside with a high pressure water hose.
Remove any scale or deposits from the waterside
surfaces and check for internal or external
corrosion and leakage.
Chapter 2-The Pressure Vessel
The fireside surfaces should also be thoroughly
cleaned so that metal surfaces, welds, joints, tube
ends, fittings and any previous repairs can be
readily checked.
Be sure that steam valves, system valves, (hot
water) feedwater valves, blow-off valves, all fuel
valves, valves to expansion tanks, and electrical
switches are shut off prior to opening handholes,
manhole and front or rear doors. Adequately vent
the pressure vessel prior to entry. Flashlights
rather than extension cords are recommended as a
safety factor. Cleaners should preferably work in
pairs.
Clean out the low water cut-off piping, the water
level controls and cross connecting piping. Replace
water gage glass and clean out water cocks and tri-
cocks. Also check and clean drain and blowdown
valves and piping.
Check all water and steam piping and valves for
leaks, wear, corrosion and other damage. Replace
or repair as required.
J. PREPARATION FOR EXTENDED
lAY-UP
Many boilers used for heating or seasonal loads or
for stand-by service may have extended periods of
non-use. Special attention must be given to these
so that neither waterside nor fireside surfaces are
allowed to deteriorate from corrosion.
There are two methods of storage - wet or dry.
Your water consultant or feedwater treating com-
pany can recommend the better method depending
upon circumstances in the particular installation.
Whichever method is used, common sense dictates
a periodic recheck of fireside and waterside con-
ditions during lay-up to allow variations from the
above methods for special area or job-site con-
ditions.
Swing open boiler head at stack end of unit to
prevent flow of warm, moist air through boiler
tubes.
Although pollution control regulations may con-
tinue to limit the permissable sulphur content of
fuel oils, care must be taken to avoid corrosion
problems that sulphur can cause, especially in a
boiler that is seasonally shut down. Dormant
periods, and even frequent shutdowns, expose the
fireside surfaces to condensation below the dew
point during cooling. This moisture and any
sulphur residue can form an acid solution. Under
certain conditions, and especially in areas with
high humidity, the corrosive effect of the acid will
be serious enough to eat through or severely
damage boiler tubes or other metal heating sur-
faces during the time that a boiler is out of service.
This condition does not generally occur during nor-
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