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Form 2055
16
Revision Date 5/1/2015
3 . 8 . 2 M A I N T E N A N C E
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 I N S P E C T I O N
To examine for scratches, shine a bright concentrated light at about a 45 Deg angle. Anything
that glistens brightly should be inspected closely. Any scratch 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 R E P L A C E M E N T O F G L A S S
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 G E N E R A L
Corrosion damage to boilers is often the result of improper lay-up during non-operating periods.
Substantial damage can occur in only a few days if 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 by either 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 an
insulating scale on the boiler when it is returned to service. These corrosion products will
accumulate on critical heat transfer areas of the boiler, increasing the potential for localized
corrosion and overheating.