Answer
The latest marine fuel specification standard is ISO 8217:2024, 7th Edition, published in May 2024. It replaced ISO 8217:2017. The full title now explicitly covers fuels from petroleum, synthetic and renewable sources, reflecting the increasing use of VLSFO and biofuels.
ISO 8217:2017 | ISO 8217:2024 |
|---|---|
Mainly conventional petroleum marine fuels | Covers petroleum, synthetic, renewable and recycled-source hydrocarbons |
2 main specification tables | 4 specification tables |
No dedicated VLSFO table | Dedicated table for ≤0.50% sulphur residual fuel/VLSFO |
Limited FAME content | Dedicated biofuel/bio-residual grades; FAME up to 100% permitted in specified grades |
No dedicated bio-residual category | New RF bio-residual fuel grades |
Only specified maximum viscosity; caused operational issues with thin/paraffinic VLSFOs. | Enforces minimum viscosity limits across residual fuel categories (e.g., min 120 mm2/s for 380 grades) to prevent injection failure for VLSFO |
13 categories: 7 distillate + 6 residual | 21 categories/grades in the new structure |
Net Heat of Combustion was optional/not standardized for bio-blends. | Mandatory reporting of Net Heat of Combustion and Cetane Number/Oxidation Stability for bio-grades. |
General advisory clauses regarding harmful substances. | Strictly caps Organic Chlorides (max 50 mg/kg total organic halogen as chlorine) and mandates fuels be free of inorganic acids. |
1. Distillate & Bio-Distillate Marine Fuels (Table 1)
Covers 100% petroleum distillates (DM) and bio-distillates/blends (DF) containing up to 100% FAME:
- Pure Distillates (DM): DMX, DMA, DMZ, DMB.
- Bio-Distillates (DF): DFA, DFZ, DFB (plus 100% FAME grades).
2. Residual Fuels with Sulfur ≤0.50% m/m (Table 2)
Specifies Very Low Sulfur Fuel Oils (VLSFO) and Ultra-Low Sulfur Fuel Oils (ULSFO):
- Grades: RMA 20, RME 180, RMG 180, RMG 380 (with strict lower/upper viscosity bounds).
3. Bio-Residual Marine Fuels (Table 3)
Specifies residual fuel oil blended with bio-components (FAME or renewable hydrocarbons):
- Grades: RF 20, RF 80, RF 180, RF 380, RF 500 (categorized by percentage of bio-content and kinematic viscosity).
4. Residual Fuels with Sulfur >0.50% m/m (Table 4)
Specifies High Sulfur Fuel Oils (HSFO) intended for vessels equipped with operational Exhaust Gas Cleaning Systems (EGCS / Scrubbers):
- Grades: RMA 10, RMB 30, RMD 80, RMG 180/380/500/700, RMK 380/500/700.
So, 7 distillate + 4 low-sulphur residual + 5 bio-residual + 5 high-sulphur residual = 21 fuel categories/grades.
Important technical changes to remember
The most exam-relevant changes are:
- Biofuels are now properly incorporated. FAME-containing distillates and residual biofuel blends are included, with provisions extending up to 100% renewable content in applicable grades.
- VLSFO gets its own specification table. This is important because VLSFO became widespread after the IMO 2020 global 0.50% sulphur limit.
- Minimum viscosity is introduced for VLSFO grades. For example, a nominal 380 cSt low-sulphur grade has a minimum viscosity requirement, helping prevent unexpectedly thin fuels and associated purifier/fuel-system problems.
- Stability requirements are strengthened. TSP—Total Sediment Potential—is particularly relevant for VLSFO stability assessment.
- For DF/bio-distillate grades, FAME content, net heat of combustion, cetane number and oxidation stability receive additional attention.
- The standard now expressly addresses potentially harmful components, including provisions concerning organic chlorides, and reinforces that fuel must not jeopardize machinery, personnel or vessel safety.