inspected thoroughly. When re-installed, these
controls must be given an operational test.
3.8 WATER GAUGE GLASSES
3.8-1 INSTALLATION
Check with the maintenance supervisor and
engineering for the proper glass to be used.
Compare the box and the glass label or marking
to assure that the gauge glass ratings or
temperature and pressure are suitable for use on
the boiler. Use new gaskets when replacing
glass. The gaskets used should be the same
type as those originally supplied with the
boiler. Make certain that the gauge glass valves
are properly aligned.
All bolts and nuts must be free-running and
well lubricated, preferably with graphite type
lubricant. Washers under nuts and bolt heads
are desirable. DO NOT tighten while
equipment is in operation.
3.8-2 MAINTENANCE
Inspect the gauge glass regularly for any signs
of clouding or scratching. In new processes, the
gauge glass should be inspected daily until the
need for replacement becomes apparent. This
will help establish the routine inspection cycle.
The gauge glass should be blown down daily so
as to remove accumulated sediment from the
valves.
3.8-3 INSPECTION
To examine for scratches, shine a bright
concentrated light at about a 45
0
angle.
Anything which glistens brightly should be
inspected closely. Any scratches which glistens
and will catch a fingernail, or crescent-shaped
or star shaped mark is cause for replacement.
This is because scratches, corrosion, chips and
surface damage weaken the glass. If inner
surface appears cloudy or roughened, and will
not respond to cleaning procedures, this is
evidence of chemical attack. If severe, this is
cause for replacement.
3.8-4
REPLACEMENT OF GLASS
Any glass that has been removed from its
mounting in process boilers, regardless of the
reason for removal, should be discarded and
replaced with a new glass and gaskets. Used
glasses may contain hidden damage and
represent a safety hazard. Be sure that the
replacement glass is suitable for service
conditions. Protective shields to keep cold air,
water, or falling objects from glass must be
replaced.
3.9 IDLE BOILER CARE AND LAY-UP
3.9-1 GENERAL
Corrosion damage to boiler is often the result
of improper lay-up during non-operating
periods. Substantial damage can occur in only a
few days in proper precautions are not taken.
This damage is irreversible and will reduce
boiler reliability, increase maintenance costs
and eventually shorten the life of the boiler.
Idle boilers are vulnerable to attack when air
contacts untreated wet metal surfaces. To
prevent corrosion, the boiler metal must be
protected by either keeping the surfaces
completely dry or excluding air from the boiler.
Air exclusion is accomplished either by
keeping the boiler completely full of water
(short term lay-up) or filling the boiler with
nitrogen gas (long-term lay-up). The nitrogen
gas prevents air infiltration and does not react
with the metal.
In addition to the corrosion damage that occurs,
the metal particles that are released will form