Short Term Boiler Layup Procedure Typically, a short term boiler layup is considered any duration less than 30 days. This covers a lot of the short term plant shutdowns for various repair, maintenance, or other associated tasks. Short term layups can also be due to external reasons, separate from the boiler room, which result in the elimination of any boiler operation for a limited time. A wet boiler layup is often used for short term shutdowns to minimize water waste but a dry boiler layup would be required if freezing temperatures are expected. Semi-Short Term Boiler Layup Procedure Semi-short term boiler layups are a category where the length of the layup is unknown but may last beyond the short term layup timeframe and up to 60 days. While a dry boiler layup is preferred, a wet boiler layup may be used depending on the exact circumstances. Long Term Boiler Layup Procedure Long term boiler layups are the layups that last more than 30 days and are often associated with yearly seasonal shutdowns or indefinite plant shutdowns. A dry boiler lay-up is the best plan for these longer shutdowns to ensure the boiler does not experience any corrosion.