Overview
ISO/TS 11366:2011 - "Petroleum and related products - Guidance for in-servicing of lubricating oils for steam, gas and combined-cycle turbines" provides practical guidance for in-service monitoring, sampling and testing of mineral turbine lubricants. It applies to oils classified in ISO 6743-5 and specified in ISO 8068, and is aimed at helping power equipment operators and lubricant specialists evaluate oil condition, understand deterioration mechanisms and implement corrective actions to maximize service life.
Key topics
- Scope and applicability: Mineral turbine oils and control fluids for steam, gas and combined‑cycle turbines (including single‑shaft combined cycles and systems with separate circuits).
- Factors affecting service life: oil system design, condition at start‑up, original oil quality, operating temperature, contamination and purification provisions, and oil make‑up rates.
- Deterioration mechanisms: oxidation, viscosity change, sludge and deposits, particulate contamination, water ingress, rust/corrosion (including copper protection), foaming and air‑release loss, and increasing acidity.
- Recommended tests & interpretation:
- Physical and sensory: appearance, colour, odour
- Chemical: total acid number (TAN), remaining oxidation stability
- Physical properties: kinematic viscosity, flash point
- Contamination & wear: particle counting, sludge/deposits
- Water management: water content, water separability, demulsibility
- System performance: foaming characteristics, air‑release, rust prevention
- Sampling guidance: sampling point selection, sampling lines and containers, sample marking and handling (references ISO 3170, ISO 3722, ISO 4021).
- New oil & in‑service examination: recommended tests on new oil deliveries and routine testing frequency and procedures for oils in service.
- Action thresholds: advice on corrective actions when characteristics reach condemning limits (to preserve turbine reliability).
Applications
ISO/TS 11366 is used by:
- Power plant maintenance and reliability engineers for turbine lubrication programs
- Lubricant analysts and oil laboratories to develop meaningful sampling and testing schedules
- Condition monitoring teams to interpret oil test data (TAN, viscosity, particle counts, water separability, oxidation stability)
- Asset managers implementing oil life‑extension and contamination control strategies
Practical benefits include earlier detection of oil degradation, reduced unplanned downtime, optimized oil change intervals, and extended component service life.
Related standards
- ISO 8068 - Specification for turbine lubricating oils (family T)
- ISO 6743-5 - Lubricant classification (referred lubricant categories)
- ISO 3170, ISO 3722, ISO 4021 - Sampling and sampling‑container methods
- Derived from IEC 60962 (technical basis)
Keywords: ISO/TS 11366, turbine oil, lubricating oils, oil sampling, oil testing, oxidation stability, water separability, viscosity, total acid number, turbine maintenance, in-service monitoring.