There are two primary ways to care for an out-of-service boiler. These are usually chosen on the basis of whether freezing temperatures will exist while the boiler is stored and whether the boiler may be needed for service on short notice. The boiler can be stored dry or wet. In either case, it should be thoroughly cleaned before storage.

Dry Storage

The cleaned boiler should be thoroughly dried. Any moisture will cause corrosion on long standing. All lines to the boiler that could carry moisture back to the boiler must be blocked off. Remember, even air can carry moisture.

Moisture absorbing material may be placed on trays inside the shell at the rate of 2 lbs. of quick lime or 10 lbs. Of silica gel for each 1,000 gal. of capacity. Periodic inspections of the effectiveness of these materials are recommended during extended storage.

Wet Storage

The cleaned boiler should be closed and filled to overflowing using chemically conditioned water (condensate is purer than feedwater for this purpose). Caustic soda is often used for this treatment at a concentration of 450 ppm with an oxygen scavenger such as sodium sulfite at 200 PPM. Water pressure greater than atmospheric should be maintained during storage.