Overview
ISO 13686:2013 - Natural gas - Quality designation - defines the parameters and conventions needed to describe finally processed and, where required, blended natural gas intended for pipeline transmission and custody transfer. The standard lists the composition parameters, physical properties, units and references to measurement standards but does not set numerical quality limits. Informative annexes illustrate typical values and national methods (with emphasis on health and safety) and include guidance on interchangeability.
Key topics and technical requirements
- Scope and definitions: clear terms for natural gas, liquefied natural gas (LNG), substitute natural gas, raw gas and local distribution systems (LDS).
- Quality designation parameters: required parameters to describe gas at pipeline level, including
- gas composition (major, minor and trace components)
- gas properties - calorific value (superior/inferior), density, relative density, compression factor, Wobbe index, dew points
- trace constituents relevant to health, safety and materials compatibility
- Units, symbols and reference conditions: standardized symbols and ISO reference conditions (e.g., p = 101,325 kPa; T = 288.15 K) to ensure consistent reporting and calculations.
- Sampling and measurement: references to established measurement standards and analytical methods (gas chromatography, Karl Fischer water determination, sulfur and mercury methods) to define how parameters should be measured and reported.
- Interchangeability guidance: treated in Annex A and further illustrated in informative annexes covering methods such as AGA index, British Hydrocarbon Equivalence, Weaver and national codes (e.g., DVGW G 260, EN 437).
Practical applications and target users
ISO 13686:2013 is intended for professionals who need a consistent, international framework to describe natural gas quality:
- Gas producers and processors defining pipeline-quality specifications
- Transmission and distribution system operators (TSPs, DSOs)
- Gas measurement and custody-transfer teams
- Laboratory analysts and instrumentation suppliers (chromatography, dew point analyzers)
- Regulators, safety engineers and standards developers assessing health, safety and interchangeability issues
- Buyers, sellers and traders needing unambiguous quality designation for contracts
Using ISO 13686 helps ensure interoperable gas trade, consistent reporting of calorific value and Wobbe index, and reduced risk when blending or revaporizing LNG and substitute natural gases.
Related standards
ISO 13686 cross-references and complements several ISO standards on measurement and properties, for example:
- ISO 6974 series (gas composition by GC)
- ISO 6976 (calorific value, density, Wobbe index calculations)
- ISO 15970 / 15971 (measurement of volumetric properties, calorific value)
- ISO 13443 (standard reference conditions)
- ISO 10101 (water determination)
These related documents provide the measurement methods and calculation rules referenced by ISO 13686:2013.
