25 May 2005
Quicklime or Silica Gel Layup Method. This procedure is recommended
for storage over 150 days or for less than 150 days when the boiler room and
atmosphere is quite humid and not well ventilated. The recommended procedure
consists of eight basic steps:
1. Take the boiler out of service and drain completely while still warm. Make
sure that water walls and gauge columns are not overlooked.
2. Lock and tag out the boiler in accordance with written procedures.
3. Break the feedwater and steam connections to the boiler and blank off
connections if other boilers in the plant are operating.
4. The boiler may be opened and the water-contacted inside surface washed
to remove all loose scale and sediment by flushing thoroughly with high-
5. Use a stiff brush to clean all internal surfaces that can be reached.
5. Start a very light fire in the furnace to dry out the boiler water-contacted
surfaces. Maintain this fire for at least 2 hours or until inspection shows no
moisture on internal sections of the boiler.
6. Place quicklime (not hydrated lime) or new, unused silica gel in one or
more metal or fiber trays in the boiler. Place the trays on wood blocks so
air can circulate under them. The amount of lime or silica gel required is
about 22 kilograms (50 pounds) per 0.36 kilogram of steam per second
(3000 pounds per hour) boiler capacity.
7. Seal the boiler to prevent any moist air from entering the boiler.
8. Open and inspect the boiler every 2 months. Replace any moist quicklime
or silica gel with new material.
9. Carefully reseal immediately after the inspection and after the addition of
Wet Layup of Boilers
. This method means that the boiler
completely full of treated water. This method is easier to check and the boiler can be put
back in service more quickly. This method should not be used if the boiler is subject to
Wet Layup without Draining (Operational Boilers)
. This method
most commonly when a boiler is to be shut down for 4 to 30 calendar days. Often the
boiler must be maintained in a standby condition. Corrosion will most likely occur in the
boiler unless both the water level in the steam drum and the chemicals in the boiler are