World Bunkering > News > Summer 2009 > Protecting against chemical contamination

Andrew Shaw

Chemical contamination in bunker fuels; what is it? Why does it occur? What are the damaging chemicals and effects on the ships’ engines? What are the common testing techniques used by laboratories? And what protection can the ship operators expect?

You may have recently seen an increase in the number of news items talking about chemically adulterated fuel. It has been well debated and discussed but looking forward, how does the industry detect and protect against chemical contaminants in bunker fuel? There have been many cases of fuels containing chemical contaminants which have caused anything from an “inconvenience” to a “catastrophic failure”. In all cases a common feature has been the fact that the ship in question has suffered damage but a test report to ISO8217 parameters has indicated the results to be “on specification”.

Today the common reference for both buyer and seller is the international bunker fuel standard ISO8217:2005 which covers various characteristics of the commodity in question. It is of course perfectly feasible that a ship operator may request any number of additional tests to be done to further protect the engine, but these more investigative tests often incur more time and cost. Is it a realistic option to be spending increasing amounts on testing when the fuel is in say, 85% of cases perfectly “fit for purpose”? Well, it may be worth it when the damage caused by fuels that are not fit for purpose due to chemical contamination can run into millions of dollars.

The shipowner is currently protected within the ISO8217:2005 standard by clause 5.1 which states: “The fuel shall not contain any added substance or chemical waste which: jeopardises the safety of ships, or adversely affects the performance of machinery, or is harmful to personnel, or contributes overall to air pollution.” Thus if a chemical can be detected in a fuel that is considered to have caused damage to the engine, then this would form the foundations of a claim against the fuel supplier for delivery of non-compliant fuel.

The problem in the chemical contamination debate is the way in which the laboratory test methods may or may not be able to identify a potential contaminant. In the event it is a clean or “pure” chemical the only effect on the current test parameters may be to lower the density and/or viscosity. Whilst this may have stood out as being unusual in the past, with the current increased blending due to the demand for low-sulphur fuels of a lower density or viscosity, it is no longer such a good indicator. In fact many contamination cases have been a direct result of the blending stocks containing the chemicals. Now we have defined the problem and explained why this is such an issue we should look at a selection of those cases that are known and recognised from the past (see table below).

It can be seen just from the selection below that the contaminants are wide and varied. The very fact that some of the recent contaminations are combinations of clean chemicals further demonstrates the challenges that exist in the industry.

The most recent problem area that has been identified is the inclusion of biofuels in the supply chain. Biofuel/waste will typically contain fatty acid methyl ester (FAME), which has been reported to have caused corrosive damage. If biofuels are used as blending stock this type of damage may become more common.

Theory behind the various detection equipment

Now we have examined the cause and effects of chemical contamination, what are the analysis techniques being used in the testing laboratories?

FTIR (Fourier Transform Infra Red)

Infra Red spectroscopy passes IR radiation through a sample. Some of the IR Radiation is absorbed into the sample and some is passed through it (transmitted). The generated spectrum is a representation of the molecular absorption and transmission, creating a molecular fingerprint of the sample. An Infra Red spectrum shows absorption peaks which correspond to the frequency of vibrations between the bonds of the atoms making up the sample. Because each different material is a unique combination of atoms, no two compounds will produce the same Infra Red spectrum.

Therefore the FTIR technique can positively identify the presence of a wide range of materials (known as qualitative analysis). Also the size of the peak of an FTIR scan is a direct indication of the amount of material present and can also be used to gain a reasonable idea of the quantity of the contaminant in the sample (semi quantitative). Often FTIR may act as a trigger for further analysis such as GC-MS.

GC-MS (Gas chromatography-mass spectrometry)

GC-MS has become a widely used and powerful tool, often the preferred technique for problematic fuel investigations. GC-MS is most effective when IR (the technique above) has highlighted a specific contaminant. The GC uses a capillary column to “in simple terms” separate the components of the oil. The differing molecular properties of the sample will separate as it travels through the column and allows the MS to capture, ionize, and detect the ionized molecules separately. The mass spectrometer does this by breaking each molecule into ionized fragments.

A skilled technician is needed to select the correct set up of the instrument. In addition the best sample preparation method needs to be identified prior to analysis; the wrong method could lead to damaging chemicals becoming masked by the natural constituents of the fuel oil.

Injecting the fuel directly into the instrument is known as “direct injection”. This process is used mostly for high molecular weight compounds.

Headspace GC-MS is a process that involves heating the sample to “drive off” the volatile compounds in the fuel. The gas produced in the headspace is injected and analysed. This is a quicker and cleaner method but is very limited as it can only be used to detect Volatile Organic Compounds (VOCs).

Various extraction methods are also commonplace, often adopted when the contamination is a fatty acid or other acidic compound.

Other Techniques

In addition to FTIR and GC-MS techniques, there are other tools available which have been in existence for many years and can be used in detection and identification of contaminants. The biggest problem in approving a method for the detection of chemical contaminants in bunker fuels is that there is no single or standard testing method that can be adopted to detect any possible chemical contamination, which may have found its way in to the fuel.

The topics of testing techniques and common methods were debated during the Singapore Bunker Conference (SIBCON) last year and a call was made to the testing industry to try and standardise the testing and detection of chemical contaminants.

It was suggested that all the testing companies should contribute to a standard which could be adopted throughout the industry to test and report the presence of chemicals. Whether this will gain momentum we are still unsure and the problem remains a complex one that will not be resolved quickly, as each specific contaminant will require differing techniques of preparation before analysis by FTIR, GC-MS or any other method.

Future updates of ISO8217

The International Maritime Organization (IMO) has put pressure on the International Organisation for Standardisation (ISO) to “fast track” the next revision of ISO8217 to meet the needs of MARPOL Annex VI. The ISO working group committed to issuing the new version of the standard has confirmed that they will deliver the new version of ISO8217 before July 2010. Although it is a little early to say with any confidence what changes will be included in the new version, there is already much speculation that it should include clauses detailing which chemicals should not be present in bunker fuels. However, until the industry has clear boundaries as to what is considered a chemical contamination, at what levels they must not be present and by which methodology they will be detected, it is likely that cases of fuel contamination will only increase.

Until such information is available, it seems that it is down to the individual fuel testing agencies to work with shipowners to offer the best possible protection, not only by testing to standard ISO8217 test parameters, but by also finding ways of looking for significant levels of potentially damaging chemical contaminants in each and every bunker fuel sample that is tested.