At some point in time you may wish take your boiler off line and store it for an extended period of time. Be very cautious. Boilers that sit idle will corrode leaving you with a quite a mess when you want to place the boiler back in service.
Here are two ways you can store your boiler.

The first is wet storage, which is generally better for shorter periods of time. In fact, we would recommend wet storage for anybody that needs a boiler for emergency stand-by. A word of caution, make sure the temperatures in your boiler room do not dip below freezing.

For wet storage we recommend the following steps:

1. Inspect the boiler and clean it if needed

2. Fill the boiler with deaerated feedwater to the normal levels

3. Contact your water treatment company for the chemicals needed to condition the water

4. An alternative would be using a nitrogen blanket throughout the entire boiler. Make sure the vents are closed and that the nitrogen pressure is greater than atmospheric pressure.

The dry storage method is preferred for boilers that will be out of service for an extended period of time or where the temperatures can go below freezing.

1. Again, inspect and clean your boiler

2. Drain all the water and make sure that the boiler is completely dried. Remember, any moisture left on boiler surfaces will eventually corrode

3. Next make sure that moisture cannot enter the boiler. Close off any steam lines, feed lines and any points of entry for air

4. Then place moisture absorbent material, such as quicklime or silica gel inside the boiler. This should be placed on trays inside the boiler. We suggest 2 pounds of quicklime or 5 pounds of silica gel per 30 cubic feet of boiler volume.

5. Close up all manways and handholes

6. Next place a sign on the boiler so that nobody makes the mistake of firing it without removing the absorbent material. This sign might read as follows:

Attention - moisture absorbent material has been placed in the water side and furnace of this boiler. This material must be removed before water is placed in the boiler and before the boiler is fired.

7. Finally, inspect the boiler every two or three months and replace the absorbent materials with new or regenerated materials.

Reference :
Website http://www.mckenziecorp.com/boiler_tip_3.htm

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