Marine Fuel Glossary

Bunkering has its own commercial vocabulary. These are the terms that appear most often in enquiries, nominations, delivery notes and claims.

Ordering and delivery

• Stem — a confirmed bunker order for a specified grade, quantity, port and delivery window.
• Nomination — the buyer's instruction confirming the vessel, quantity and delivery date to the supplier.
• Ex-wharf — delivery at a berth or pipeline rather than by barge.
• Ex-pipe — delivery through a shore pipeline connection.
• BDN — bunker delivery note, the document evidencing what was delivered, when and to which vessel.
• MFM — mass flow meter, a metering system that records delivered mass directly and reduces quantity disputes.
• Pumping rate — the rate at which fuel is transferred, a common source of delay and demurrage exposure.

Grades and specification

• VLSFO — very low sulphur fuel oil, commonly 0.50% sulphur maximum.
• ULSFO — ultra low sulphur fuel oil, commonly 0.10% sulphur maximum, used in emission control areas.
• HSFO — high sulphur fuel oil, used by vessels with exhaust gas cleaning systems.
• MGO / MDO — marine gas oil and marine diesel oil, distillate grades.
• ISO 8217 — the international specification standard for marine fuels.
• Cat fines — aluminium and silicon catalyst particles that cause engine wear if not removed.
• Viscosity — resistance to flow, which determines heating and handling requirements.
• Flash point — the temperature at which vapour ignites; a safety-critical minimum.

Compliance and environment

• IMO 2020 — the global 0.50% sulphur cap on marine fuel introduced in January 2020.
• ECA / SECA — emission control areas with stricter sulphur limits.
• Scrubber — exhaust gas cleaning system permitting continued HSFO use.
• Biofuel blend — a marine fuel containing a biogenic component, often described as B24 or B30 by blend share.
• EEXI / CII — vessel efficiency and carbon intensity measures that affect operating profiles and fuel demand.

Commercial and claims

• Off-spec — delivered fuel failing the agreed specification.
• Quality claim — a claim raised on the basis of representative sample analysis.
• Quantity dispute — a disagreement over delivered volume or mass.
• Retained sample — the sealed sample kept as evidence for any later claim.
• Credit line — the financing limit that determines what a buyer can lift and from whom.