CHAPTER7
Rear Door
The
rear
door
seals
the chamber into which
com·
bustion gases flow after exiting the third pass and
from which the gases are exhausted through the
vent opening.
The
rear
door
is insulated
with
a cerawool
material
which
is
stabilized
with
a
ceramic
rigidizer.
When the
door
is
open for annual inspection,
reapply the rigidizer to maintain a durable
sur-
face.
Q.
OPENING AND CLOSING
DOORS
Opening Front
or
Rear Door
!WARNING
Before loosening the
door
bolts,
tighten the
nut
on
the
davit arm
stud
to
support
the
door
and
avoid
the
possibility
of
serious
personal Injury
or
death.
This will prevent sagging and facilitate opening
of
the door.
CAUTION
Do
not
open
a
boiler
when
the
boiler
is
hot.
Rapid
cooling
by
exposure
to
ambient
air
temperature
may
cause damage
to
the
refractory
or
to
the
boiler
itself.
After opening either door, support the open door
with blocks
or
a
jack
and check the gaskets and
sealing surfaces.
If
the door gaskets are hard
or
brittle, they should
be
replaced. The sealing sur-
CHAPTER 7-20
INSPECI10N AND MAINTENANCE
faces
of
the
door
and tube sheet should be clean.
Make
sure that all gasket retaining fasteners are
in
place.
Closing and Sealing Doors
Coat the
door
gasket with an oil and graphite
mixture.,
Swing
the
door
to
the closed position
and
run all
of
the retaining bolts in until snug.
Tighten the bolts evenly, starting at the top center
and alternating between the top and bottom bolts
until both are tighL
Do
not overtighten. Tighten
alternate bolts until all are secure and the door
is
gas tighL
CAUTION
After
closing
the
door,
loosen
the
nut
on
the
davit
arm
stud
to
release
tension
on
the
davit
arm. Failure
to
do
so
may
result
In damage
to
the
boiler
due
to
thermal
stresses
during
boiler
operation.
After the boiler
is
back in operation, retighten the
door bolts
to compensate for compression
of
the
gasket
or
movement
of
the door.
R.
LUBRICATION
Electric Motors
Manufacturers
of
electric motors vary in their
specifications for lubrication and care
of
motor
bearings, and their recommendations should
be
followed.
Ball bearing equipped motors are pre-lubricated.
The
length
of
time a bearing can run without
having grease added will depend upon many
factors.
The
rating
of
the motor, type
of
motor
enclosure,
duty,
atmospheric
conditions,
humidity, and ambient temperatures are but a few
of
the factors involved.
750-150
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