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COLUMBIA BOILER COMPANY, REV 2-17
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Boiler Lay-Up
When a boiler is taken out of service,the unit should be cooled until the water is below the
atmospheric boiling point or to a temperature suitable for site specific requirements. The
boiler may then be drained and flushed out and an inspection should be made to deter-
mine what repair work, if any, is necessary and what cleaning should be done. A decision
should then be made to employ dry or wet storage.
Whenever a package boiler is taken out of service for any purpose, it should be internally
cleaned when put back into service or placed in wet or dry storage. Loose material in the
form of dirt, trash, mill scale, or deposits should be removed by washing or other mechan-
ical methods.
Dry Storage
Dry storage is a procedure preferable for boilers out of service for extended periods of
time or in locations where freezing temperatures may be expected during storage.
The cleaned boiler should be thoroughly dried, since any moisture left on the metal surface
would cause corrosion to occur on long standing. Precautions should be taken to preclude
entry of moisture in any form, into the water side of the unit.
To prevent moisture attack during dry storage, moisture absorbing material such as quick-
lime at the rate of 2 pounds or silica gel at the rate of 10 pounds for 1000 gallon capacity,
may be placed on trays inside the boiler to absorb moisture from the air. The hand holes
should be closed and all connections on the boiler be tightly blanked. The effectiveness of
the materials for such purposes and need for their renewal may be determined through
regular internal boiler inspections.
Wet Storage
Wet Storage is preferable when boilers are to be paced in storage condition for short peri-
ods of time, typically less than a year. The procedure should not be employed for boilers
in locations where freezing temperatures may be expected during standby.
The cleaned boiler should be filled to the top using condensate or feed water, either of
which should be conditioned chemically to minimize corrosion during standby and closed.
Prescribed concentrations of caustic soda and of scavenger such as sodium sulfite may be
employed. Concentrations of approximately 450 parts per million (ppm) of caustic soda
and 200 ppm of sodium sulfite may be used for this purpose.
You should consult your boil-
er water treatment company for the specific requirements at your site.
Water pressure
greater than that of the atmosphere should be maintained within the boiler during the stor-
age period.
The percentage of soda and sulfite noted above is greater than recommended
for operation of the unit. It will be necessary to completely drain the unit prior
to placing it on-line and to treat the water during operation according to the
recommendation of the boiler water treatment company employed.
NOTICE