Overview
ISO 19636:2019 - Ships and marine technology - General requirements for inclinometers used for the determination of trim and list of LNG carriers - specifies general requirements for the accuracy, installation, calibration and verification of trim and list inclinometers used on LNG carriers. The standard focuses on instruments used to correct cargo tank level measurements for ship inclination, and on ensuring reliable input to custody transfer measurement systems (CTMS).
Key Topics
- Scope and purpose: Requirements target inclinometers used for determining trim and list for on-board cargo level measurement and custody transfer applications.
- Accuracy and uncertainty: Defines inherent error assessment (Factory Acceptance Test, FAT), reference standard uncertainty for Site Acceptance Test (SAT), and integrated overall accuracy for shipboard operation.
- Installation & alignment: Guidance on mounting location, levelling (adjustable base plate with screws), correct X/Y axis alignment relative to longitudinal/transverse axes, and considerations for dry dock, floating dock or moored conditions.
- Design requirements:
- Typical ranges (example): list axis ~ −5° to +5°, trim axis ~ −2° to +2°; LNG carriers typically operate within ±1° list and ±3 m trim.
- Outputs: analogue 4–20 mA and digital (fieldbus/serial) communication options.
- Protection box requirements for non-hazardous and hazardous zones, including intrinsic safety isolators and metal containment.
- Security & sealing: Measures to prevent unauthorized adjustment; physical sealing of protection box required for custody transfer use until scheduled calibration.
- Verification & certification: Visual inspection, verification test procedures, sealing, and issuance of certificates following FAT/SAT and verification testing.
- Safety: Conformance to electrical and hazardous-area standards (e.g., IEC 60079-0) and to classification society rules.
Applications
- Ship operators and owners of LNG carriers: ensure accurate cargo level measurements and regulatory compliance during custody transfer.
- Equipment manufacturers and system integrators: design inclinometers and protection enclosures that meet ISO 19636:2019 requirements.
- Marine surveyors and classification societies: perform FAT/SAT, alignment verification, sealing and certification.
- Terminal operators and contractual stakeholders: rely on standardized inclinometer performance for accurate custody transfer documentation in CTMS.
Related Standards
- IEC 60079-0 (Explosive atmospheres - Equipment - General requirements) - referenced for hazardous-area equipment.
- Guidance and industry practice from IMO, ICS, OCIMF, GIIGNL, SIGTTO - recommended for safety and operational context.
Keywords: ISO 19636:2019, inclinometer, LNG carriers, trim and list, custody transfer, calibration, installation, verification, 4–20 mA, fieldbus.