Marine Fuel Analysis — ISO 8217 / MARPOL Annex VI

What Is Marine Fuel?

Marine fuel analysis is the measurement of specification parameters for the distillate (DM) and residual (RM) fuel classes defined in ISO 8217. Kinematic viscosity, density, sulfur, flash point, pour point, carbon residue, ash, water, total sediment, aluminium+silicon (catalyst fines), and CCAI calculation fall within this scope.

Purpose of Marine Fuel

The purpose is to verify that the fuel can be safely burned in the ship's engine and complies with the MARPOL Annex VI sulfur limits. Non-conforming bunker fuel leads to engine damage and sanctions in port state control.

Which Products Is Marine Fuel Applied To?

Residual bunker fuels (RMG, RMK)
Distillate marine fuels (DMA, DMB)
Very low sulfur fuel oils (VLSFO)
Ultra low sulfur fuel oils (ULSFO)
Marine gas oil (MGO)

In Which Sectors Is Marine Fuel Used?

Oil & GasPetrokimyaEnergyMaritimeMaritime Transport

Standards Related to Marine Fuel

ISO 8217 (specifications of marine fuels)
ISO 3675 / ISO 12185 (density)
ISO 3104 (kinematic viscosity)
ISO 8754 / ISO 14596 (sulfur)
ISO 10307-2 (total sediment after ageing)
IP 501 / IP 470 (metal content)
ISO 3733 (water content)

Marine Fuel Conditions

Sampling: MARPOL bunker sample is taken during delivery and sealed
viscosity temperature: 50 °C for residual fuels, 40 °C for distillates
sulfur limit: The general MARPOL limit and the emission control area (ECA) limit are different
Tortu: Post-aging residue indicates risk of incompatibility and sedimentation

Equipment for Marine Fuel

Kinematic viscosity bath
XRF or UV fluorescence sulfur analyser
Total sediment filtration setup
ICP-OES (metal content)
Carbon residue and ash furnaces
Flash point and pour point apparatus

Sample Requirements for Marine Fuel

Sampling determines the validity of the result in fuel analysis: ISO 3170 (manual) and ISO 3171 (automatic in-line) define the sampling rules. The sample must be taken into a clean container of a suitable material, filled with no air gap, and kept cold for volatile products.
The MARPOL sample must be sealed, labelled and accompanied by a delivery note
Residual fuel samples are homogenised by heating before analysis
The sampling point (delivery line) and date must be recorded
A compatibility test must be requested when different fuels are mixed

Duration of Marine Fuel

The standard bunker analysis package takes a few working days. Compatibility and stability tests require additional time; a fast-track package can be arranged separately for urgent bunker decisions.

Marine Fuel Procedure

1The sealed sample is received and its identity verified.
2Residual samples are homogenised by heating.
3Density and viscosity are measured; CCAI is calculated.
4Sulfur, water, ash and carbon residue are determined.
5Total sediment and metal content are analysed.
6Results are compared against the ISO 8217 limits.

Marine Fuel Acceptance Criteria

ISO 8217 defines parameter limits for each fuel class. On the sulfur side, the MARPOL Annex VI general limit and the stricter limit in emission control areas apply separately. Acceptance criteria come from the relevant product specification and vary by season, market and grade. Specification versions are updated; The current limit values to be applied to your product are confirmed in the specification text at the bidding stage.

Evaluation of Results

Catalyst fines (aluminium+silicon) are a critical parameter in residual fuels: abrasive particles rapidly wear the fuel pump and injectors, and the efficiency of the onboard purification system becomes decisive. Mixing different bunkers can cause precipitation due to incompatibility; a compatibility test must be performed before mixing.

Marine Fuel Report

Sample description, seal number and delivery information
Fuel class and applied specification
Method, result and limit for each parameter
CCAI calculation
Comparison of the sulfur result against the MARPOL limits

Accreditation

EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.

Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.

Scope and authorisations

Related Regulations

MARPOL Annex VI (prevention of air pollution from ships)
(EU) 2016/802 Sulphur Content of Liquid Fuels Directive

Petroleum, Fuel and Oil Analysis — What Does This Testing Field Cover?

The section below describes the field that the Marine Fuel test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.

Petroleum, fuel and oil analysis determines whether a fluid meets its specification and how it behaves in use. Standards in this field consist largely of ASTM and EN publications, with a separate method defined for each parameter.

What distinguishes this family is that product specifications are written as PARAMETER LISTS. Specifications such as EN 590 (diesel), EN 228 (petrol), EN 14214 (biodiesel) and ISO 8217 (marine fuels) state for each parameter both the limit and the method by which that limit is to be measured. If the method changes the result may change too; the specification therefore binds the method as well, and the use of an "equivalent method" is possible only where the specification allows it.

On the fuel side, parameters describe three different properties of the product. Physical properties (density, viscosity, distillation curve, pour point, cloud point) determine pumpability and cold weather behaviour. Combustion properties (cetane number, octane number, calorific value) indicate performance in the engine. Contaminant and stability parameters (sulphur, water, sediment, oxidation stability, copper strip corrosion) affect both emissions and storage life.

Oil analysis is carried out for two different purposes and the two must not be confused. Analysis of NEW oil verifies the conformity of the product to its specification: viscosity index, additive content, flash point. Analysis of USED oil, by contrast, is done to read the condition of the machine — elemental analysis shows wear metals (iron, copper, chromium, aluminium), water and fuel contamination point to leaks, and oxidation and acid number determine the remaining life of the oil.

Used oil analysis is therefore a PREDICTIVE MAINTENANCE tool. The trend of samples taken at regular intervals is followed; it is the trend rather than a single result that is meaningful. Iron levels climbing over the course of months allow intervention before a failure occurs.

Marine fuels are the most active sub-body of the field. The global tightening of sulphur limits has brought new blended fuels onto the market; for these fuels stability, compatibility (whether two fuels form deposits when mixed) and catalytic fines content have become critical parameters.

Sampling is part of the result in this family too. A sample taken from the bottom of a tank shows different water and sediment content from one taken from the upper level; in commercial deliveries the sampling point and method are set by contract.

Method groups in this field

Physical properties
Density (oscillating U-tube and hydrometer), kinematic viscosity, distillation, pour and cloud point, flash point.
Combustion properties
Cetane number and cetane index, research and motor octane number, calorific value.
Sulphur and elements
Sulphur by UV fluorescence and XRF; elemental analysis and additive content by ICP.
Stability and corrosion
Oxidation stability, copper strip corrosion, water and sediment, filter blocking tendency.
Composition analysis
Boiling range distribution by gas chromatography, hydrocarbon types (FIA), benzene and aromatics content, fatty acid methyl ester content.
Used oil
Wear metals, contamination (water, fuel, soot), oxidation, acid and base number, change in viscosity.

Commonly confused in this field

The specification binds the method as well; a result measured by a different method may not be accepted for specification conformity.
A single result on used oil is not meaningful; the decision is made on the trend.
The sampling point determines the result; the tank bottom and the upper level show different water and sediment.
The cetane index is a calculated value and is not the same thing as a measured cetane number.
Fuels blended with biodiesel behave differently in terms of storage life and microbial growth; classical diesel parameters are not sufficient.
Mixing marine fuels from different sources can cause deposits; compatibility is assessed separately.

Which decisions these results support

Conformity of a fuel lot to specification and commercial delivery
Predictive maintenance decisions based on used oil analysis
Determining parameters for customs and tax classification
Quality verification after storage, blending and transport
Compliance with sulphur limits under emissions legislation

Related Tests

Frequently Asked Questions About Marine Fuel

Can we mix fuels taken at different ports?

It is a risky practice. When two incompatible residual fuels mix, asphaltene precipitation occurs and tanks and separators clog. A compatibility test must be performed before mixing.

We use VLSFO — what additional risks are there?

Low-sulfur blends are made from different components; stability, cold-flow and lubricity behaviour can differ from conventional fuels. Pour point and total sediment should be particularly monitored in these fuels.