Significance and Use 5.1 Insoluble material may form in oils that are subjected to oxidizing conditions. 5.2 Significant formation of oil insolubles or metal corrosion products, or both, during this test may indicate that the oil will form insolubles or corrode metals, or both, resulting in varnish formation during field service. The level of varnish formation in service will be dependent on many factors (turbine design, reservoir temperature, duty-cycle, for example. peaking, cycling, or base-load duty, maintenance, and so forth) and a direct correlation between results in this test and field varnish formation are yet to be established. 5.3 Oxidation condition at 120 °C under accelerated oxidation environment of Test Method D4310 and measurement of sludge and RPVOT value could reflect a practical oil quality in actual turbine operations. Results from this test should be used together with other key lubricant performance indicators (including other established oxidation and corrosion tests) to indicate suitability for service.Scope 1.1 This test method is used to evaluate the sludging tendencies of steam and gas turbine lubricants during the oxidation process in the presence of oxygen and metal catalyst (copper and iron) at an elevated temperature. This test method may be used to evaluate industrial oils (for example, circulating oils and so forth). 1.2 This test method is a modification of Test Method D4310 where the sludging and corrosion tendencies of the same kinds of oils are determined after 1000 h at 95 °C in the presence of water. Water is omitted in this modification. 1.3 The values stated in SI units are to be regarded as standard. 1.3.1 Exception—The values in parentheses in some of the figures are provided for information only for those using old equipment based on non-SI units. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.5 WARNING—Mercury has been designated by many regulatory agencies as a hazardous substance that can cause serious medical issues. Mercury, or its vapor, has been demonstrated to be hazardous to health and corrosive to materials. Use Caution when handling mercury and mercury-containing products. See the applicable product Safety Data Sheet (SDS) for additional information. The potential exists that selling mercury or mercury-containing products, or both, is prohibited by local or national law. Users must determine legality of sales in their location. 1.6 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.
