ISO 8068:2024

Overview - ISO 8068:2024 (Lubricants for Turbines)

ISO 8068:2024 specifies minimum requirements and test methods for lubricating oils used in most power-generation turbines. It covers steam turbines, gas turbines, single-shaft combined-cycle turbines with common lubrication systems, and hydraulic turbines (but not wind turbines, which are covered by ISO 12925-1). The standard is intended to be used in conjunction with ISO 6743‑5 (family T classification) and defines categories for mineral, synthetic and fire‑resistant turbine oils delivered for service.

Key technical topics and requirements

• Scope of lubricants: mineral oils (API groups I–III and GTL group III+), synthetic oils (polyalphaolefins - API IV, esters - API V), environmentally acceptable synthetics for hydraulic turbines, and phosphate‑ester fire‑resistant fluids.
• Functional properties and test focus:
  • Viscosity classification and absence of viscosity index improvers.
  • Oxidation/ageing stability (TOST and related methods).
  • Water content and demulsibility/steam demulsibility (important for steam and combined-cycle grades).
  • Filterability: procedures for wet and dry filterability (ISO 13357 series).
  • Foaming, air release and water separability (relevant to turbine lubrication reliability).
  • Environmental criteria for THCH/THCE grades: biodegradability and aquatic toxicity (tests such as ISO 9439, ISO 14593, ISO 6341, ISO 14669 referenced).
  • Compatibility and material effects, e.g., rubber swelling/corrosion testing (ISO 1817, ISO 2160).
• The standard references a broad suite of normative test methods (ISO and some ASTM/EN methods) rather than listing absolute performance numbers in the narrative; specific limits are given in the standard’s specification tables (Tables 4–12).

Practical applications - who uses ISO 8068:2024

• Lubricant manufacturers: to formulate and certify turbine oils for specific turbine categories and environmental classes.
• Turbine OEMs and operators: to select oils that meet durability, thermal stability and compatibility needs for steam, gas and combined‑cycle plants.
• Power plant engineers & maintenance teams: for procurement specs, oil testing, condition monitoring and reliability planning.
• Testing laboratories and certification bodies: to perform the referenced test methods and verify compliance.
• Regulatory and environmental managers: to ensure hydraulic‑turbine lubricants meet biodegradability and aquatic toxicity expectations.

Related standards

• ISO 6743‑5 (family T classification) - intended companion document
• ISO 12925‑1 - wind turbine lubricants (outside ISO 8068’s scope)
• Key test standards cited: ISO 3104, ISO 760, ISO 13357‑1/2, ISO 4263‑1/3, ISO 9439, ISO 14593, ASTM D2272, EN 14832/14833

Practical takeaway: Use ISO 8068:2024 to define, test and specify turbine oils that meet modern performance, reliability and environmental requirements across steam, gas, combined‑cycle and hydraulic power applications.