Most fuel quality problems cannot be seen at the manifold, so the samples taken during delivery and the specification written into the order are the ship's main protection. This guide covers correct sampling, the ISO 8217 editions, the parameters that matter and the practical steps if a result comes back off-spec.
Why the sample matters more than the paperwork
A bunker delivery note records what the supplier says it delivered. A properly drawn, sealed and witnessed sample is the only physical evidence of what actually arrived on board. A sample taken badly, at the wrong point or without witnesses loses much of its value as evidence, whatever the laboratory later finds.
Sampling at the manifold
The IMO guidelines for fuel oil sampling, adopted as resolution MEPC.182(59), set the sampling point for the MARPOL sample at the receiving ship's inlet bunker manifold. The sample is drawn continuously throughout the delivery, using a manual continuous drip sampler or an automatic time-proportional or flow-proportional sampler.
- Check before delivery that the sampler is clean, correctly fitted and that the collection container is new.
- Keep the drip running from the start to the end of the transfer, including any top-up at the end.
- Mix the collected fuel thoroughly before dividing it into bottles, with both parties present.
- Seal each bottle with a tamper-evident seal, fitted by the supplier's representative in the presence of the ship's representative, and record every seal number on the delivery documents.
- Label each bottle with the vessel, port, date, grade, supplier, seal number and signatures.
Industry standard ISO 13739 also allows sampling at either end of the bunker hose, and some ports set their own procedures. Agree the sampling point and method before the hose is connected, and record any disagreement in a letter of protest.
Which samples to keep
- MARPOL delivered sample: at least 400 ml, kept under the ship's control until the fuel is substantially consumed and for not less than 12 months from delivery. It is for statutory verification and is released only to the authorities.
- Ship's commercial retained sample: kept on board for quality checks and any commercial follow-up.
- Supplier's retained sample: handed to the barge, with a signed receipt.
- Laboratory sample: sent immediately for testing.
The BIMCO Bunker Terms 2018, for example, call for at least five samples, two kept by the seller and three, including the MARPOL sample, kept on board. Store all samples in a cool, sheltered place outside the accommodation, away from heat and sunlight.
MARPOL Annex VI also provides for in-use and on-board samples taken from the ship's own system. Ships built before 1 April 2022 must have in-use sampling points fitted or designated by their first IAPP renewal survey on or after 1 April 2023.
ISO 8217: 2017 or 2024?
ISO 8217 sets the specifications for marine distillate and residual fuels. The seventh edition, ISO 8217:2024, was published in May 2024. Both it and the 2017 edition remain in commercial use, so the edition must be stated in the enquiry and the stem confirmation.
The main changes in the 2024 edition include:
- Four tables instead of two: distillates, residual fuels at or below 0.50% sulphur, bio-residual blends, and residual fuels above 0.50% sulphur.
- Distillate grades that allow FAME content up to 100%, with new requirements such as cetane number and oxidation stability.
- A minimum viscosity for residual fuels, and reporting of total sediment existent and accelerated alongside total sediment potential for residuals at or below 0.50% sulphur.
- A limit on organic chlorides (50 mg/kg, by EN 14077) and general requirements that now apply to every table.
The benefits of the newer edition only apply if the fuel is actually supplied against it. If the contract says 2017, the 2017 limits govern.
Key parameters and why they matter
- Viscosity: determines the heating needed for correct injection. Too low can be as much of a problem as too high.
- Density: affects purifier performance and is used to convert delivered volume into mass.
- Catalytic fines (aluminium plus silicon): hard particles from refinery processes that cause abrasive wear of pumps, injectors, rings and liners if not removed by purification.
- Water: reduces energy content and can affect combustion and corrosion.
- Sulphur: a statutory limit as well as a specification parameter. Under MARPOL, the sulphur content declared on the BDN is the binding figure, even if a commercial test differs.
- Flash point: SOLAS generally requires at least 60°C for fuel used on board, as a fire safety measure.
- Total sediment potential: an indicator of stability and the risk of sludge formation in storage.
If test results come back off-spec
An off-spec result needs a documented response. The priority is the safety of the ship and its machinery, then preserving the evidence.
- Read the report carefully. Note which parameter is outside the limit, by how much, and against which edition of ISO 8217. Ask the laboratory whether the deviation is within the test method's reproducibility.
- Check for statutory issues. A flash point below 60°C or sulphur above the applicable limit is more than a commercial matter. Inform the flag administration and class and follow their guidance, which may include debunkering. Blending on board to bring the fuel within limits is not acceptable.
- Segregate the fuel. Keep it in its own tanks, close cross-connections and do not blend it with other fuel.
- Avoid consumption where possible. If the ship has no alternative, ask the laboratory and engine maker for handling advice on heating, purification and filtration, and monitor the machinery closely.
- Notify the supplier in writing promptly, quoting the stem, BDN and seal numbers. Contracts set time limits for raising quality concerns; the BIMCO Bunker Terms 2018, for example, require notice within 30 days of delivery.
- Keep all samples sealed and untouched. Record their location and condition, and do not send the MARPOL sample anywhere unless the authorities request it.
- Document everything: engine and purifier logs, filter and purifier sludge samples, photographs, damaged parts and all correspondence. Inform owners, charterers and the P&I club as appropriate.
Prevention is cheaper
Specify the edition and grade clearly, buy from suppliers with a sound quality record, sample correctly on every delivery and, where practical, wait for laboratory results before burning new fuel. Atlas Bunkering strongly recommends an independent bunker surveyor and accredited laboratory testing for every stem, and can arrange both on request.
Questions and answers
How long must the MARPOL sample be kept?
Under the ship's control until the fuel is substantially consumed, and in any case for at least 12 months from the date of delivery.
Which ISO 8217 edition should I specify?
State an edition explicitly in every enquiry and confirmation. Many buyers now prefer ISO 8217:2024 for its wider coverage, but check what suppliers in the port can supply against, and check the engine maker's guidance.
Should I stop using new fuel until test results arrive?
Where the tank arrangement allows, it is good practice to keep new fuel segregated and unused until results are in. If that is not possible, monitor purifiers, filters and engine performance closely.
Sources
- IMO Guidelines for the sampling of fuel oil, resolution MEPC.182(59) (AMSA copy)
- IMO: Fuel oil availability and quality, MARPOL Annex VI regulation 18
- ISO 8217:2024 Specifications of marine fuels
- UK P&I Club: ISO 8217:2024, the marine fuel standard has been updated
- ExxonMobil Marine: Bunker sampling, MEPC.182(59) and ISO 13739
- Cayman Islands Shipping Registry: Guidance on off-specification fuels
This guide is general information, not legal or technical advice. Check the current rules and your engine maker's guidance for your vessel.