This standard specifies the classification, technical requirements, test methods and inspection rules of marine medium- and low-pressure piston air compressors. It is applicable to motor-driven medium- and low-pressure air compressors with rated exhaust pressures of 3.0 MPa, 1.0 MPa and 0.7 MPa. The standard also covers the requirements for marking, Encasement, transportation and storage. Marine air compressors driven by diesel engines and marine air compressors with Miscellaneous rated exhaust pressures not greater than 4.0 MPa can be implemented by reference. The standard refers to relevant standards for materials and test methods, ensuring the standardization and conformity of the design, production and acceptance of equipment.