ISO 4261:2013

Overview

ISO 4261:2013 - Petroleum products - Fuels (class F) specifies quality and acceptability requirements for gas turbine fuels used in industrial, public utility and marine applications (non-aviation). The standard defines fuel properties at the time and place of custody transfer, gives methods for sampling and testing, and provides guidance on calculating lower calorific value and on trace metal limits for fuel entering turbine combustion chambers. It is intended for turbine manufacturers, fuel suppliers, purchasers and operators.

Key topics and technical requirements

• Fuel categories and properties: Defines fuel categories (distillates, residuals, low- and medium-flash fuels) and limits for core properties such as:
  • Flash point (e.g., inland 38 °C; higher limits for marine use)
  • Kinematic viscosity (minimum ~1.3 mm2/s at 40 °C; higher maxima depending on category)
  • Density at 15 °C
  • Distillation characteristics (90% recovered limits for some categories)
  • Carbon residue, ash, water, sediment and copper corrosion
  • Sulfur content (category-dependent limits)
  • Calculated net specific energy (lower calorific value) - method provided in Annex A
• Sampling and test methods: Sampling per ISO 3170 / ISO 3171 or equivalent; test methods referenced throughout (e.g., ISO 2719, ISO 3104, ISO 3405, ISO 3675, ISO 3733, ISO 6245). Precision and interpretation follow ISO 4259.
• Trace metals and contamination: Annex B gives guideline limits and analytical considerations for trace metals (vanadium, sodium, potassium, calcium, lead) that affect high-temperature corrosion and turbine life. These limits apply to fuel entering combustion chambers and may require additional handling, purification or quality control.
• Additives and low-temperature operability: Additives are permitted if they do not cause the fuel to exceed specification limits. Low-temperature operability limits must conform to local requirements and be agreed when invoked.

Applications and who uses it

• Developing fuel supply contracts and specifications for power plants, industrial turbines and marine gas turbines.
• Setting quality-control procedures at loading, storage and point-of-use to avoid contamination and corrosive trace metals.
• Guiding turbine manufacturers in defining acceptable fuel characteristics and advising end-users on fuel handling/treatment.
• Supporting fuel testing laboratories and procurement teams in verifying compliance with fuel quality requirements.

Related standards

• ISO 3977 - Gas turbine procurement and operation guidance
• ISO 8217 - Marine fuels specifications
• ISO 10370, ISO 2719, ISO 3104, ISO 3405, ISO 3170/3171, ISO 8754, ISO 2160, ISO 4259 - referenced test and sampling methods

ISO 4261:2013 is a practical reference for ensuring reliable gas turbine performance, reduced corrosion risk and consistent fuel quality across industrial and marine operations.