ASTM D 4304:2025

1.1 This specification covers mineral and synthetic (API group I, II, III, or IV) oils used in steam and gas turbine lubrication systems where the performance requirements demand highly refined mineral or synthetic base oils compounded with rust and oxidation inhibitors plus selected additives as needed to control foam, wear, demulsibility, and so forth. This standard may also be applied to "combined cycle" turbine systems, where a single lubricant circulating system is used to supply oil to a steam and gas turbine configured in tandem either on a single or separate shaft for enhanced energy efficiency. 1.2 This specification is intended to define the properties of mineral and synthetic oil-based turbine lubricating oils that are functionally interchangeable with existing oils of this type, are compatible with most existing machinery components, and with appropriate field maintenance, will maintain their functional characteristics. 1.3 This specification is intended to define only new lubricating oil before it is installed in the machinery. 1.4 This specification is intended to be used as a guide. It is possible that oils that do not meet this specification may perform satisfactorily in some turbines. 1.5 This specification does not include API Group V fluids. For polyol ester fluids used to lubricate land-based gas turbines, the user is referred to the current version of military specification MIL-PRF-23699 for fluid performance requirements. For phosphate ester fluids used as turbine lubricants or steam turbine electro-hydraulic control (EHC) fluids, the user is referred to the current version of Specification D4293 for fluid performance requirements. 1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

75.100