Boilers used for steam and energy production, or operations such as washing, are sometimes taken offline for inspection and maintenance, or kept for backup use. Another common time for boilers to be out of service is during shipment or while in storage at a new plant still under construction.
In each of these cases, proper boiler lay-up and preservation is critical to ensuring a good startup experience. Without adequate protection, corrosion can begin speedily and result in many unpleasant surprises for the person who comes to restart the system. Lay-up of previously used boilers can be especially difficult because it is hard to completely drain the water from a system and keep it moisture-free. This increases the chance that some form of corrosion will appear on interior metal boiler surfaces before the boiler is put back into use.