Analysis of fuel samples


Published: 8 March 2019

Top view of a large empty container ship and a tanker standing side by side

2018 saw a huge increase in bunker quality disputes, starting around March/April with bunkers stemmed in Houston and gradually spreading to different regions and countries.

It is also predicted that there may be issues regarding fuel quality due to blending in order to provide IMO 2020 Sulphur Cap compliant fuel.

Whilst the purpose of this article is not to discuss either the Houston bunker problems or the 2020 Sulphur cap, inevitably, if there is a dispute as to the quality of the stemmed bunkers, it will be necessary to have those bunkers tested and analysed by a laboratory. The purpose of this article is to bring into focus the need for a proper fuel testing and analysis regime to be in place.

Testing fuel samples on board is possible but there are limitations as to these findings which generally are limited to density, viscosity, pour point, water content and compatibility. Whilst on-board testing is useful to get early indications of problems, it is not sufficient to test for some of the issues we have seen in recent times, for example the presence of contaminants such as phenolic compounds. Increasingly we understand that Owners routinely send bunker samples for laboratory testing for the presence of these compounds.


Correct sampling and which samples are to be tested and analysed are just as important as the analysis itself. In most cases the relevant contract between the parties specifies which samples are to be used for analysis (and be binding) and how those samples are to be collected. For example, the BIMCO Bunker Terms 2018, stipulate at Clause 4 (a) that: -

".... a primary sample shall be drawn at a point, to be mutually agreed between the Sellers and the Buyers.... closest to the Vessel's bunker manifold and otherwise in accordance with the procedures set out in IMO Resolution MEPC.182(59) Guidelines for the Sampling of Fuel Oil for Determination of Compliance with MARPOL 73/78 Annex VI or any subsequent amendments thereto..."

In terms of quality claims, at Clause 9(b)(ii): -

"In the event that a claim is raised.... the Parties hereto shall have the quality of the Marine Fuel analysed by a mutually agreed, qualified and independent laboratory"

For time charters, the BIMCO Bunker Quality Control Clause for Time Chartering provides that: -

"(3)... during bunkering representative samples of the fuel(s) supplied shall be taken at the Vessel's bunkering manifold and sealed in the presence of competent representatives of the Charterers and the Vessel...(4)...and any dispute as to whether the bunker fuels conform to the agreed specification (s) shall be settled by analysis of the sample(s)....whose findings shall be conclusive evidence as to the conformity or otherwise with the bunker fuel specification(s)"

The MEPC.182(59) Guidelines for the Sampling of Fuel Oils are benchmark guidelines to ensure the integrity of the sampling process and sets out details such as sample location, handling and storage. In relation to the sampling method used to take samples from the manifold, as set out in the above clauses, the guideline recommends that the sample should " drawn continuously throughout the bunker delivery period".

Occasionally, it may be necessary to obtain a representative sample from the bunker tanks, although there may be question marks as to whether this is truly representative of the bunkers as stemmed due to the presence of previous bunkers or the presence of sludge in the tank, for example. Various methods of tank sampling are possible, but some are more representative than others. It is important in this regard to include on the sample bottle a label which details the method used.

In all the examples above, it is important to seal and label the bottles correctly. The MEPC.182(59) guidelines provide details of how to do this and this guide should be consulted. It is also important to ensure that a sufficient volume of sample is collected. From the collecting device it is usually recommended that five samples are collected; the MARPOL sample, supplier's sample, vessel's own retained sample, on-board analysis sample and sample for independent analysis.


A suitable testing laboratory should be agreed upon in advance and set out in the contract. For example, in the BIMCO Bunker Quality Control Clause for Time Chartering there is a provision to stipulate in the contract the agreed testing laboratory. If this has not been done then the parties should agree on a laboratory to test the agreed, binding, sample. Such a laboratory should be qualified, independent and accredited and capable of undertaking the specific tests and analysis required. It should also be noted that not all laboratories allow the testing to be witnessed and the parties will need to bear in mind if that is acceptable to them. It should also be noted that where there are samples to be tested under both a charterparty and a bunker supply contract then the same laboratory should be used for both samples in order to ensure the same methodology and processes are applied.

There should also be an agreed testing protocol as agreed between the parties' experts as this will avoid any later arguments between the parties as to method of testing. Typically, we see the following testing undertaken: -

  • ISO 8217 Table 2 testing
  • GC-MS of neat fuel by direct injection
  • Headspace GC-MS of neat fuel
  • FTIR analysis of neat fuel
  • Solid phase extraction followed by GC-MS and FTIR analysis of polar extracts

The results of the analysis will then be measured against specifications of the fuel as stipulated under the relevant charterparty or bunker supply contract i.e. typically ISO 8217 (and whichever version is agreed e.g. 2012, or 2017). The results will show whether the fuel was on specification under the ISO 8217 "Table 2" requirements, which set out limits for, amongst other things, sulphur, water and aluminium. Further gas chromatography testing, combined with mass spectrometry (GC-MS) will provide analysis of the fuel for the purposes of the remainder of Clause 5, such as indicating whether the fuel is "free of any material that renders a fuel unacceptable for use in marine applications".

In summary, there are many potential pitfalls with fuel sampling and testing. Ideally, issues around sampling and testing should be agreed upon in advance and set out in the charterparty or bunker supply contract and ahead of any issues arising. With limited samples available it's important to get it right the first time.