1.1 This guide provides personnel who have a limited microbiological background with an understanding of the symptoms, occurrence, and consequences of chronic microbial contamination. The guide also suggests means for detection and control of microbial contamination in turbine oils and turbine oil systems. This guide applies primarily to turbine lubricants (see Specifications D4293 and D4304) and turbine oil systems. However, the principles discussed herein also apply generally to lubricating oils with viscosities <100 mm²/s (for example, see Specification D6158).

1.2 This guide focuses on turbine system and turbine oil microbiology. Despite considerable differences in turbine systems (for example, gas and steam driven turbines; power generation and propulsion; etc.) as ecosystems for microbial communities – with the exception of temperature – these differences are largely irrelevant. Ambient temperatures are typically similar. Recirculating turbine oil temperatures are commonly >40 °C. However, generally speaking, all systems in which accumulations of free water can develop, share properties that are considered in this guide.

1.3 This guide complements Energy Institute’s Guidelines on detecting, controlling, and mitigating microbial growth in oils and fuels used at power generation facilities (2.2). The Energy Institute’s guidance document provides greater detail than the overview provided in this guide.

1.4 Microbial contamination in turbine oil systems shares common features with microbial contamination in fuel systems (See Guide D6469). However, there are also relevant differences. Although the chemistry of the fluids is different, this Guide draws heavily on D6469 but highlights unique aspects of turbine oil and turbine oil system biodeterioration and microbial contamination.

1.5 This guide is not a compilation of all of the concepts and terminology used by microbiologists. It provides basic explanations of microbial contamination and biodeterioration in turbine oils and turbine oil systems.

1.6 The values in SI units are to be regarded as the standard.

1.7 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.

1.8 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.