Overview
ISO 6583:2024 - "Methanol as a fuel for marine applications - General requirements and specifications" defines quality, sampling and testing requirements for methanol supplied at the point of custody transfer for use as a marine fuel (diesel engines, fuel cells and other marine uses). The standard covers methanol from all forms of production and may also be applied to similar land-based uses. It was developed with input from shipowners, engine and fuel-cell designers, fuel suppliers, testing laboratories and classification societies.
Key topics and technical requirements
- Scope and sampling
- Specifies properties at the point of custody transfer.
- Sampling best practice: glass sample bottles with UV‑resistant caps; minimise exposure to atmospheric moisture.
- Methanol grades
- Three grades: Marine Methanol Grade A (MMA), Grade B (MMB) and Grade C (MMC) with progressively wider tolerances.
- Core characteristics and limits (when tested by the referenced methods)
- Appearance: homogeneous, clear, free of suspended matter (IMPCA 003).
- Density at 15 °C: typical pure methanol ≈ 796.1 kg/m3; Table limits - min 795.0 kg/m3 (all grades); max 797.0 kg/m3 (MMA/MMB), 798.0 kg/m3 (MMC) (ISO 12185).
- Methanol mass fraction (dry basis): MMA/MMB ≥ 99.85%; MMC ≥ 99.70% (IMPCA 001).
- Impurities (dry basis): MMA/MMB ≤ 0.15%; MMC ≤ 0.30% (IMPCA 001).
- Ethanol: max 50 mg/kg (MMA/MMB), 150 mg/kg (MMC).
- Acetone: max 30 mg/kg (all grades).
- Total sulfur: max 0.5 mg/kg (MMA/MMB), 10 mg/kg (MMC) (ASTM D5453).
- Water: max 0.100% mass (MMA/MMB), 0.500% (MMC) (ASTM E1064).
- Distillation range (IBP–DP): max 1.0 °C for MMA/MMB; report IBP and DP (ASTM D1078). Distillation helps identify cross‑contamination.
- Chloride: max 0.5 mg/kg (IMPCA 002); Acidity (as acetic acid): max 30 mg/kg (ASTM D1613).
- Lubricity and particle count: to be agreed between buyer and seller (IP PM FK, IP PM FI); recommended in MMA for stricter machinery protection.
- Testing and dispute resolution
- Lists normative test methods (IMPCA, ISO, ASTM, IP). ISO 4259-2 applies for interpretation of precision where available.
Applications and users
- Practical uses: marine diesel engines, marine fuel cells, auxiliary systems and similar land‑based installations.
- Primary users: shipowners/operators, fuel suppliers, methanol producers, engine/fuel‑cell manufacturers, classification societies, fuel testing labs and regulators.
- Benefits: consistent fuel quality, reduced engine damage risk, simplified contractual specifications and international trade.
Related standards and notes
- Key referenced methods: IMPCA 001/002/003, ISO 12185, ASTM E1064, ASTM D1078, ASTM D5453, ASTM D1613, IP PM FK, IP PM FI.
- Safety note: methanol has a low flash point (~11 °C) - follow safety data sheets and applicable regulations.
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