This standard specifies the water quality requirements for the operation of marine auxiliary boilers. It is applicable to bunker oil boilers, exhaust gas boilers and bunker oil exhaust gas combined boilers with a design pressure of not more than 2.5MPa and a medium of water and saturated steam. The standard specifies the boiler water quality indicators, especially in the chemical treatment of feed water of steam boilers, and provides detailed water quality requirements and management recommendations. This standard aims to ensure the efficient and safe operation of marine boilers and reduce corrosion and damage to equipment caused by water quality problems. It is an important reference document for the operation and maintenance of ships.