Dry Lay-Up A dry lay-up is intended for a long term shutdown or where the possibility of freezing is present. It is achieved by draining the idle boiler of all water and sealing it in a dry state. This process does not require constant monitoring of the water. Wet Lay-Up A wet lay-up is intended for short term dormancy when there is no risk of experiencing freezing temperatures. Nitrogen Lay-Up A nitrogen lay-up is an additional step that can be implemented in either a wet or dry lay-up to add a nitrogen blanket to prevent oxygen from entering the boiler.