Overview
ISO 18132-1:2011 - "Refrigerated hydrocarbon and non‑petroleum based liquefied gaseous fuels - General requirements for automatic tank gauges - Part 1" - defines general principles for the accuracy, installation, calibration and verification of automatic tank gauges (ATGs) used for custody transfer measurement of liquefied natural gas (LNG) on board marine carriers and floating storage. The standard covers fully or partially refrigerated LNG (near atmospheric pressure) and specifies technical requirements for data collection, transmission and reception. Detailed technical requirements and accuracy limitations for specific ATG types are provided in the annexes.
Key topics and technical requirements
- Scope & definitions: ATG, ATG system, CTMS (custody transfer measurement system), radar‑type, capacitance‑type, float‑type ATGs.
- Safety & compliance: Conformance with electrical area classification (e.g., IEC 60079‑0), classification society rules and national regulations; emphasis on safe handling of cryogenic/hazardous environments.
- Design requirements:
- Mechanical rigidity, gastight tank penetrations, chemical compatibility with LNG, low‑temperature tolerance.
- Provisions for routine maintenance, self‑diagnostics and verification with tanks in service.
- Dynamic response to track levels during filling/emptying; minimum measurable level; data filtering/averaging; redundancy and sealing/security.
- Installation: Siting, protection of tank surfaces, and prevention of measurement interference (vortex/boiling effects).
- Accuracy & calibration:
- Calibration reference methods and readout resolution.
- Recertification procedures, maximum permissible error and calibration frequency (see annexes for specifics).
- Data handling: Requirements for reliable data collection, transmission and reception as part of an ATG or CTMS.
- Annexes: Normative guidance for radar, capacitance and float ATGs plus informative annexes on accuracy limitations and uncertainty.
Practical applications and users
ISO 18132-1 is essential for organizations involved in LNG custody transfer and on‑board measurement, including:
- LNG carrier and floating storage (FSO/FPSO) operators
- Naval architects and shipyards specifying ATG installations
- Measurement & instrumentation manufacturers (ATG, CTMS)
- Classification societies, regulatory bodies and inspection agencies
- Third‑party verifiers and calibration laboratories
Use cases include design and acceptance of on‑board ATG systems, procurement specifications, type approval, commissioning, periodic calibration/recertification and dispute resolution during LNG trading.
Related standards
- IEC 60079‑0 (electrical apparatus in explosive atmospheres) - referenced for electrical area classification
- IACS Unified Requirements (e.g., E10) - for type approval and environmental considerations
- ISO 18132 series: Part 2 (shore tanks) and Part 3 (LPG/chemical gases) for related measurement contexts
Keywords: ISO 18132-1, ATG, automatic tank gauge, LNG custody transfer, calibration, verification, radar-type ATG, capacitance ATG, float ATG, CTMS.