MARPOL Annex VI Fuel Oil Sampling: 12-Step BDN Checklist

Updated 29 September 2026 · marpol-annex-vi, bunkering, marine-engineering, compliance

A MARPOL Annex VI fuel oil sampling and bunker delivery note checklist for engineers comes down to four jobs. MARPOL Annex VI is the international rule set that governs fuel oil quality and sulphur limits for ships. First, you draw the sample continuously at your own inlet manifold — the pipe connection where fuel enters your ship during delivery. Second, you check every field on the BDN, the bunker delivery note that is your paper record of what fuel you received, before anyone signs it. Third, you seal and label the sample with the supplier present. Then you keep both the sample and the BDN on board for as long as the rules require.

Most guides stop there. The hard part of bunkering is different: the barge that won't sample at your manifold, the BDN that turns up late with the wrong density, and the seal number — the unique code stamped on the sample bottle and its label to prove no one has tampered with it — that doesn't match the bottle. This guide covers the rules quickly. Then it spends most of its length on those arguments, because that is where a fuel quality dispute is won or lost, and a dispute over bad fuel can be expensive and slow to resolve without good records.

The 12-step MARPOL Annex VI sampling checklist

This is the working sequence, split into before, during and after delivery. Your company's bunkering procedure and the charter party come first wherever they are stricter.

Before the hose is connected

1. Check the stem against the ship's records. Confirm grade, quantity, sulphur limit, density, delivery port and supplier identity before the barge is alongside, so any mismatch on paper shows up before fuel moves.
2. Check the blank BDN form. Make sure the supplier's template has every Appendix V field, because a missing field is easier to raise now than after delivery.
3. Prepare the sampling kit at your manifold. Fit clean containers and a sampler at the receiving manifold that can drip continuously for the whole delivery, and check the containers and seals for damage.
4. Agree the samples in advance. Settle how many samples will be taken, how they will be sealed and who gets which before pumping starts. West P&I's bunker quality disputes bulletin, checked September 2026, describes five samples as typical practice, but your charter party or company may set a different number.

During delivery

5. Open the drip at the start and keep it running to the end. A sample taken only at the beginning or the end is not representative, and that is the first thing a lab or a lawyer will question.
6. Keep a sampling log as you go. Write down the sampling point, date, port, ship name and IMO number, and the seal numbers you plan to use, so the label is filled in from records rather than from memory.
7. Watch the collected volume. Check that the drip rate will give enough fuel for every sub-sample at IMO's 400 ml minimum from MEPC.1/Circ.875/Add.1 (checked September 2026).
8. Take soundings and meter readings by your ship's procedure. No single mandatory measurement method or tolerance appears in the sources reviewed for this checklist, so follow the method your company has approved and record every reading.

After delivery

9. Check the BDN against what actually arrived. Compare quantity, density, sulphur and product name with your soundings and the stem, and make sure the supplier's representative has signed the conformity declaration.
10. Seal and sign the sample together. The supplier's representative and the master or responsible officer sign after bunkering is complete, with both present at the moment of sealing.
11. Match every seal number. The number on the bottle, on the label, in your sampling log and on the BDN or sample receipt must be identical.
12. File the records. Keep the BDN and the MARPOL sample for the periods set out in regulation 18, and keep sounding sheets, meter tickets, sampling logs, protest letters and lab reports for as long as your company or the dispute process requires.

MARPOL Annex VI fuel oil sampling: what the rules require

The rules ask for one representative sample. It must be drawn continuously through the whole delivery, at the receiving ship's inlet bunker manifold — the pipe connection where fuel enters your ship. That sample is then sealed, signed and kept under the ship's control. These rules are set by the International Maritime Organization (IMO), the United Nations agency that regulates shipping, through its Marine Environment Protection Committee (MEPC). IMO resolution MEPC.182(59), read on 29 September 2026, puts the sampling point at the receiving ship's inlet manifold. It says the drip runs from the start of the delivery to the end.

The custody rules — who signs the sample and for how long it must be kept — come from regulation 18 of Annex VI. Regulation 18, checked in September 2026, says the sample is sealed and signed by the supplier's representative and by the master or the officer in charge of bunkering, once the delivery is complete. The same regulation says the ship keeps the sample until the fuel is substantially consumed, and for no less than 12 months from delivery. It also says the BDN — the bunker delivery note, the paper receipt for the fuel — stays on board, readily available for inspection, for three years after delivery.

Volume matters more than people expect. A sub-sample is one of the smaller bottles split off from the main sample so each party involved — the ship, the supplier, a shore laboratory — gets its own sealed portion. IMO guidance MEPC.1/Circ.875/Add.1, checked September 2026, says each sub-sample is typically 500 to 750 ml, and in any case at least 400 ml. If the drip is set too slow, the bottle comes up short. A short sample can't be split properly between everyone who needs one, and that shortfall becomes an argument later.

Keep one distinction clear. IMO's index of Annex VI guidelines, checked September 2026, lists the 2020 Guidelines for on-board sampling of fuel oil as applying to regulations 14 and 18. Those guidelines deal with designated sampling points — fixed locations on board set aside for testing fuel that is already in use or carried for use, not the fitting used for an incoming delivery. That is a separate job from the delivery sample taken at the manifold during bunkering. A port state inspector may ask about either one, so know where both points are on your ship.

Samples, records and how long each is kept

The table below sets out what each item is and where the retention rule comes from. The MARPOL figures are from the regulation 18 text and the multi-sample practice is from West P&I's bunker quality disputes bulletin, both checked September 2026.

The bunker delivery note checklist, field by field

A BDN is complete when it carries every field in Annex VI Appendix V and the supplier has signed the conformity declaration. The rule applies to ships covered by regulations 5 and 6 of Annex VI, which is almost every ship an engineer reading this will join.

West P&I's loss prevention bulletin, checked September 2026, lists the fields to check line by line:

1. Receiving vessel name and IMO number, spelled exactly as on your certificates.
2. Port of delivery, which should match your port call and the stem.
3. Delivery commencement date, meaning the date bunkering started and not the date the paper was printed.
4. Supplier name, address and telephone number, so the right company can be reached in a dispute.
5. Product name, which should match the grade you ordered.
6. Quantity in metric tonnes, which you reconcile against your own soundings.
7. Density at 15°C, which feeds straight into your quantity and consumption figures.
8. Sulphur content by mass to two decimal places, which you compare against the limit for where you'll burn the fuel.
9. The supplier's signed declaration that the fuel conforms to the relevant Annex VI requirements.

Flashpoint information is the item most likely to be missing from older BDN templates. An industry summary of the IMO requirements, dated October 2025, says the BDN must state the flashpoint value in °C, or carry a statement that it has been measured at or above 70°C. It is unknown whether that reflects a new amendment or a restatement of an existing rule; check your flag's current circular before treating a BDN without it as defective.

The density figure deserves a second look. It is the number you'll use when you work out consumption and remaining on board, and a wrong density distorts every figure afterwards without setting off any alarm — the error only surfaces later, when the numbers stop adding up. The guide on how to calculate main engine SFOC and daily fuel consumption shows how far a density error travels through the daily numbers.

When the supplier pushes back: an escalation workflow

When the supplier won't cooperate, record what happened in writing, issue a letter of protest, inform the company and the charterer, and sign only for what you witnessed. No IMO document reviewed for this checklist sets out a single escalation procedure for these cases, so what follows is a sensible order of work that your company's safety management system can adjust.

The supplier refuses to sample at your manifold

The barge crew may argue that their sampling point is the standard one. They have some grounds: an ExxonMobil Marine document, checked September 2026, says ISO 13739 and ExxonMobil recommend that sampling may be carried out at either end of the bunker hose. MARPOL guidance still names the receiving ship's inlet manifold for the representative sample.

The practical answer is to keep your own continuous drip running at your manifold whatever they do at their end. Write the refusal on the sampling log, raise a letter of protest and tell the company before the paperwork is signed. Gard, the P&I club, has published guidance urging crews to take their own bunker samples because they are a vital piece of evidence, and a manifold sample you drew yourself is exactly that.

The supplier refuses to sign the sample or the declaration

An unsigned sample is weaker evidence, and an unsigned conformity declaration leaves the BDN incomplete. Ask once, in writing, for the signature. If the answer is still no, record the refusal with the time and the name of the person who refused, seal your sample with your own signature, and issue a protest that states which document is unsigned. Don't sign anything that says the sampling was witnessed jointly when it wasn't.

The BDN is late, incomplete or wrong

A BDN that arrives hours after the barge has cast off is a common irritation, and it is still a document you are required to hold. Compare it with your sampling log and soundings as soon as it arrives. If a field is missing or a figure is wrong (a density that doesn't match the stem, a sulphur value above your limit, the wrong commencement date), protest in writing, attach your own figures, and ask for a corrected BDN. Keep the original and the correction together in the file.

The seal number does not match

A seal mismatch breaks the chain of custody, and the time to catch it is while the supplier's representative is still on board. If the bottle carries one number and the label or receipt carries another, correct it in front of both parties and have both initial the correction. If it is found only after the barge has left, log the discrepancy, photograph the bottle and label, and tell the company straight away. The sample may still be useful, but its value as evidence is now open to challenge.

When to stop bunkering

The chief engineer and the master decide this, within the company's procedure. Paperwork faults are normally dealt with through protests and corrections. A wrong product, or a declared sulphur figure above the limit for where the fuel will be burned, is a different problem, and the company should hear about it before more fuel goes into your tanks. Any safety issue on the hose or manifold stops the transfer whatever the paperwork says.

Limits of any fuel oil sampling checklist

A checklist makes your records defensible, but it cannot settle every question. Five limits are worth knowing before you rely on it.

1. It cannot resolve the sampling point argument. The MARPOL manifold requirement and the hose-end practice described in the ExxonMobil document can both appear at the same delivery, and only your company and flag can tell you which prevails in a commercial dispute.
2. The number of samples varies. West P&I describes five as typical, and your charter party may ask for more or fewer.
3. Supporting records have no single retention rule. Regulation 18 covers the BDN and the MARPOL sample, and the rest depends on company and contract terms.
4. Flag and port rules differ. An engineering circular from India's Directorate General of Shipping, for example, adds checks on sample container and seal condition and on sub-sample container cleanliness that the core MARPOL text does not spell out.
5. Paperwork tells you nothing about the fuel itself. A perfect BDN and a perfect seal only prove what was delivered and declared, and the lab report tells you what you are about to burn. The fuel oil purifier troubleshooting checklist for marine engineers covers what to watch when a new stem starts behaving badly in the separators.

Who this checklist is not for

This checklist is written for ship's engineers receiving fuel. It is not a quantity survey procedure for independent bunker surveyors, and it is not a supplier's delivery procedure. It doesn't replace your company's bunkering procedure or your flag's circulars either: where either one is stricter, it wins. If your ship trades under a flag with extra sampling rules, add those to steps 3 and 10 before you print this.

Keeping bunker records digital without weakening them

Photographs and scans are useful backups to the signed originals, but they don't replace them. The sealed bottle and the ink-signed BDN are what a port state inspector or a P&I club will ask for. Photographing the seal, the label and each page of the BDN at the manifold gives you a timestamped record if the paper is later disputed or damaged.

A few habits help here. Photograph the seal number next to the label before the bottle leaves your hand. Scan the BDN the moment it arrives and file it under the delivery date. Keep your sounding and density calculations in an app that works offline. The best apps for marine engineers roundup covers scanners and note apps that behave on a ship's patchy connection, and the digital tools every chief engineer should know list shows how to organise records so the next chief can find them. For the quantity side, the offline calculator apps for fuel, units and power review looks at which calculators keep working once you are out of coverage.

FAQ

Where must the MARPOL fuel oil sample be taken?

IMO resolution MEPC.182(59), checked September 2026, places it at the receiving ship's inlet bunker manifold, drawn continuously throughout the delivery. Some suppliers point to ISO 13739 practice, which ExxonMobil describes as allowing either end of the hose. Keep your own manifold drip running in every case.

How long must the BDN and the MARPOL sample be kept on board?

The regulation 18 text checked in September 2026 says the BDN stays on board for three years after delivery. The sealed sample stays under the ship's control until the fuel is substantially consumed, and for no less than 12 months from delivery. Your company may ask for longer.

How much fuel should each sub-sample contain?

IMO guidance MEPC.1/Circ.875/Add.1, checked September 2026, gives 500 to 750 ml as typical per sub-sample and at least 400 ml in any case. Set the drip rate at the start so the total collected covers every sub-sample you agreed to take.

What should I do if the barge refuses to sign the sample label?

Ask in writing, then record the refusal with the time and the person's name. Seal the sample with your own signature and issue a letter of protest naming the unsigned document. Tell your company before the barge leaves if you can.

Is the MARPOL delivery sample the same as the in-use fuel sample?

No, they are separate samples. The delivery sample is drawn at the bunker manifold during bunkering. IMO's index, checked September 2026, links the 2020 Guidelines for on-board sampling to regulations 14 and 18, and those guidelines deal with designated sampling points for fuel in use or carried for use on board.

Verdict

The rules for MARPOL Annex VI sampling fit on one page. The work that protects your ship is the discipline around them: a continuous drip at your own manifold, a BDN checked field by field before signing, seal numbers that match everywhere, and a written protest whenever the supplier refuses something. Get those right and a fuel dispute is settled by your documents.

Related reading

• How to calculate main engine SFOC and daily fuel consumption onboard
• Fuel oil purifier troubleshooting checklist for marine engineers
• Digital tools every chief engineer should know

How this checklist was checked

This checklist covers the tools and paperwork used during bunkering. Every rule in it was checked against the IMO documents named in the text, and against the P&I and industry guidance named alongside them, on 29 September 2026. The claims list attached to this article shows which statements are the regulator's own wording and which come from third-party industry sources, so each one can be re-verified independently rather than taken on trust. Rules and industry practice change, so recheck the figures against the current IMO circular before relying on them for a specific delivery. Before your next delivery, compare this MARPOL Annex VI fuel oil sampling and bunker delivery note checklist with your company's bunkering procedure and your flag's latest circulars.