ISO 11982:2025 PDF

Overview - ISO 11982:2025 (LNG as marine fuel - On‑board measurement)

ISO 11982:2025 specifies requirements and guidance for quantifying liquefied natural gas (LNG) as a marine fuel on board LNG bunkering ships. It covers measurement during ship-to-ship (STS) transfers to LNG‑fuelled ships, STS transfers between bunkering ships, and transfers to/from shore tanks - irrespective of tank type. The standard also applies to biomethane and synthetic methane. Key goals include accurate volume, mass and energy determination and providing a consistent basis for custody transfer and bunker delivery documentation.

Key technical topics and requirements

• On‑board measurement approaches
  • Static measurement: use of tank capacity tables, liquid level/ullage measurement, temperature and pressure monitoring.
  • Dynamic measurement: flowmeter-based systems and performance/calibration requirements for custody transfer.
• Custody Transfer Measurement System (CTMS): processing inputs from ATG, thermometers, pressure gauges and generating custody transfer data on board.
• On‑board sampling and analysis: provisions for taking representative liquid and vapour samples and for online/ laboratory analysis of composition.
• Calculation methods: procedures for converting measured data into volumetric, mass and energy quantities, including liquid and vapour energy, and methods to calculate Wobbe index and methane number.
• Corrections and influences: treatment of tank trim and list, vapour pressure effects, temperature/pressure corrections and handling of unsupported components.
• Annexes: practical data processing (CTMS), calculation examples, bunker delivery note parameters and guidance for comingled LNG.

Practical applications and who uses this standard

ISO 11982:2025 is intended for organizations and professionals involved in LNG bunkering and marine fuel supply, including:

• LNG bunkering ship operators and crew responsible for on‑board measurement and reporting.
• Bunker suppliers and traders preparing bunker delivery notes (BDN) and performing custody transfer.
• Shipowners/operators of LNG‑fuelled vessels verifying received quantities and fuel quality.
• Port authorities, surveyors and regulators overseeing bunkering operations and compliance.
• Equipment manufacturers (ATG, flowmeters, CTMS, analytical systems) designing products to meet measurement requirements.
• Metrology and testing laboratories performing composition and calorific analyses.

Related standards

Normative and referenced documents cited in ISO 11982:2025 include:

• ISO 6976:2016 - gas calorific value, density and Wobbe index calculation
• ISO 23306:2020 - specification of LNG as marine fuel
• Other ISO documents referenced for terminology and equipment (e.g., ATG, tank tables, custody transfer definitions)

By standardizing on‑board measurement, ISO 11982:2025 helps ensure reliable, auditable LNG bunkering transactions and supports safe, transparent adoption of LNG (and renewable methane variants) as marine fuel.