Overview
ISO 8310:2012 - Refrigerated hydrocarbon and non‑petroleum based liquefied gaseous fuels - specifies general requirements for automatic tank thermometers (ATTs) used on board marine carriers and floating storage (FPSO/FSO). The standard covers ATTs that typically use platinum resistance thermometers (PRTs) and an indicating device for custody transfer measurement of liquefied natural gas (LNG), liquefied petroleum gas (LPG) and other refrigerated liquefied gases. It defines essential design, safety, calibration and verification procedures to ensure accurate temperature measurement (ITS‑90 referenced) for volumetric and mass calculations.
Key Topics and Requirements
- Scope and purpose: Requirements for ATTs used in custody transfer and integration into custody transfer measurement systems (CTMS).
- Temperature sensors: PRTs (three‑ or four‑wire) per IEC 60751 are preferred; manufacturers must calibrate each PRT and declare nominal resistance and constants. Routine production tests include insulation resistance, sheath integrity, dimensional and tolerance acceptance.
- Indicating devices: High‑impedance analogue inputs to minimize measurement error; consideration of electronic transmission and display.
- Installation & mounting: Minimum of three PRTs per tank (IGC Code requirement); placement and number depend on tank size/height. Provisions against pump vortexing, spray, sloshing and thermal contraction are required.
- Safety & environmental design: Gastight construction for gas‑dangerous zones, electrical area classification compliance, chemical compatibility with cargo, mechanical rigidity and low‑temperature tolerance.
- Calibration & verification: Factory calibration, post‑installation verification, and periodic accuracy checks are mandated; records of ATT calibration must be maintained.
- Performance aspects: Dynamic response, measurable temperature range, data processing and reporting, compensation for cargo temperature variation, sealing/security, redundancy and data communication.
- Type approval: Design and installation subject to approval by a national metrology institute (NMI) or classification society.
Applications - who uses it and why
- Shipowners and operators of LNG/LPG carriers, FPSOs and FSOs implementing reliable custody transfer measurement.
- Instrument manufacturers and suppliers designing and producing ATTs, PRTs and indicating devices.
- Classification societies, national metrology institutes and surveyors responsible for type approval, installation acceptance and verification.
- Terminal operators and trading parties relying on temperature accuracy for volumetric and energy/mass reconciliation during cargo transfers.
Related Standards
- IEC 60751 - Industrial platinum resistance thermometers and platinum temperature sensors (normative reference).
- IGC Code - requirements for ships carrying liquefied gases in bulk (installation and safety context).
- IACS Unified Requirements E10 - electrical considerations for equipment in hazardous zones.
ISO 8310:2012 is essential for ensuring accurate, safe and verifiable temperature measurement in refrigerated liquefied gas marine operations, supporting fair custody transfer and regulatory compliance.
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