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The nitrogen purging method for boilers can be carried out as a wet method without draining water, or as a dry method on an empty boiler. Due to the fact that nitrogen is very inert and non-corrosive, filling a boiler with nitrogen at a certain pressure can prevent oxygen from entering. For boilers with more complex structures, water can accumulate in certain areas and is difficult to remove completely; therefore, dry maintenance is not suitable, and nitrogen filling can be used instead. The method is as follows: Before shutting down the boiler, connect the nitrogen-filled pipelines; when the pressure in the boiler drops to around 0.15 Mpa, use nitrogen cylinders to supply nitrogen to areas such as the boiler drum and economizer through temporary pipelines. The specific requirements are as follows: (1) The purity of nitrogen must be over 99% ； (2) When filling the empty boiler with nitrogen, the nitrogen pressure inside the boiler should be above 0.15 Mpa ； Before filling the boiler with nitrogen using a wet method, it is advisable to add an appropriate amount of hydrazine to the boiler, and adjust the pH of the boiler water to above 10 using ammonia water ； (3) During nitrogen filling, all valves in the boiler’s steam and water system should be closed to ensure that the boiler remains airtight ； If there is a leak, it must be eliminated immediately to prevent excessive consumption of nitrogen due to the leak and to ensure that the nitrogen pressure can be maintained.