Significance and Use
5.1 This guide provides information addressing the conditions that lead to turbine oil microbial contamination and biodeterioration, the general characteristics of and strategies for controlling microbial contamination. It compliments and amplifies information provided in Practices D4378 and D6224 on condition monitoring of lubricating oils.
5.2 This guide focuses on microbial contamination in turbine oils and power generation turbine oil systems. Uncontrolled microbial contamination in turbine oils and lubrication systems remains a largely unrecognized but potentially costly problem in power generation systems.
5.2.1 Examples of turbine oil and system biodeterioration include, but are not limited to:
5.2.1.1 Filter plugging,
5.2.1.2 Oil line and orifice fouling,
5.2.1.3 Increased oil acidity,
5.2.1.4 Increased oil corrosivity,
5.2.1.5 Oil additive depletion,
5.2.1.6 Water emulsification,
5.2.1.7 Lubricity loss, and
5.2.1.8 Decreased oxidative stability and increased sludge generation.
5.3 This guide introduces the fundamental concepts of turbine oil microbiology and biodeterioration control.
5.4 This guide provides personnel who are responsible for turbine oil system stewardship with the background necessary to make informed decisions regarding the possible economic or safety, or both, impact of microbial contamination in their products or systems.
Scope
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.
1.2.1 Steam turbines, and to a greater extent hydro turbines, are continuously exposed to water ingression. Diligence is needed to ensure seals and bearings are in good condition to prevent water ingression or conditions that are conducive to biodeterioration. However, due to the risk of the accumulation of condensation, all equipment can become susceptible when shut down for extended periods.
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.
