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I. Short-term shutdown pressure maintenance Applicable to boilers that are shut down for short-term maintenance or used as backup boilers in production, with a maintenance period generally within one week. 1. After shutting down the furnace, drain all the water from it, remove any scale or slag inside, and then add qualified softened water again. 2. Heat regularly using a low flame, or use the steam from an adjacent boiler to heat the water in the boiler; the temperature of the water in the boiler should be maintained at around the ambient temperature plus 10°C in summer, and it should be ensured that the water does not freeze in winter. All drain valves, sewage valves, and water release valves should be closed to prevent leaks. 3. Supply water to the boiler regularly to maintain the pressure inside it at 0.05 MPa to 0.1 MPa, thereby preventing air from entering the boiler drum. II. Wet maintenance for prolonged shutdowns: Wet maintenance is generally suitable for shutdowns of up to one month. 1. After shutting down the furnace, drain all the water within the specified time, and remove scale, slag, and soot completely. 2. Close all manholes, access holes, valves, etc., to completely isolate it from the operating boiler. 3. Prepare an alkaline protection solution using qualified softened water; add 8 kg to 10 kg of sodium hydroxide (Na(OH)) per ton of boiler water, or 20 kg of sodium carbonate (Na2CO3), or 20 kg of sodium phosphate (Na2P03). 4. Use a dedicated pump to inject the prepared alkaline maintenance solution into the boiler. 5. Once all the protective solution has been poured in, open the water supply valve to fill the boiler with qualified softened water until water starts to overflow from the air valve. Then close the air valve and the water supply valve, and start the dedicated pump to circulate the solution and ensure even mixing. 6. Throughout the maintenance period, the furnace should be heated regularly using a low flame to keep the outside of the heated surfaces dry. The pumps should be operated periodically to ensure uniform concentration of the solution throughout the system. Additionally, samples of the solution should be taken regularly for analysis, and chemicals should be added as needed to maintain the pH level between 10 and 12, thus ensuring the alkalinity of the boiler water. 7. Appropriate anti-freezing measures should be taken in winter. III. Dry maintenance during prolonged shutdowns: Heating water boilers that are shut down for more than a month, especially those that are not in use during the summer. Dry maintenance is more suitable. 1. After shutting down the furnace, drain all the water from it, and remove the scale, slag, and soot accumulated on the heating surfaces. 2. Close the valves on the boiler’s water supply pipe, feed pipe, and drain pipe, or seal them with partitions to completely isolate it from other operating boilers. 3. Open the manholes and access holes to allow the boiler to dry naturally; if the boiler is damp, use a low heat to dry the boiler body, furnace walls, and flues. 4. Select an appropriate amount of desiccant. Common desiccants include anhydrous calcium chloride (CaCl2) and quicklime (CaO2). CaCl2 should be used at a rate of 2 kg per cubic meter of water, and particles with a size of around 15 mm are recommended ； Quicklime should be added in an amount of 3 kg per cubic meter of water, and lumps with a size of 10 mm to 30 mm are recommended. 5. After the boiler is dried, place trays containing desiccants inside the furnace and drum to absorb moisture; it is required that the desiccants do not come into direct contact with the boiler’s heating surfaces. 6. The desiccant in the boiler should be checked regularly once a week within the first month to determine whether there is any corrosion on the heated surfaces; any defective desiccant should be replaced promptly. After one month, checks should be carried out every two weeks.