Measuring marine fuel water content

The international marine fuels market is in a state of flux. Revised emission regulations instigated by the International Maritime Organization (IMO) have triggered the development of novel fuel types, which when combined with global concerns over fuel quality, will ensure that test labs with marine industry clients are kept busy for the foreseeable future.

Achieving optimal value from a fuel purchase is hugely important as marine fuel typically accounts for more than half the total operating cost of a container ship. And with depressed freight rates continuing to squeeze margins, vessel operators typically buy fuel on a purely price basis even when ‘cheap’ can be risky.

For example, grey practices by some unscrupulous fuel resellers can see bunker fuel being bulked out with water, above the permitted limit stipulated by ISO 8217:2012. This not only means that vessel operators aren’t getting what they pay for, the excess water can also trigger costly handling and maintenance issues.

With so much at stake, test labs need to ensure that they can offer their marine industry clients quick, accurate and reliable approaches for measuring the water content

A 0.5% water level – which is the upper limit of the ISO specification – would amount to 5 metric tonnes in a 1,000 metric tonne bunker delivery. At a cost of around $600 per metric tonne, this is the equivalent of $3,000. Water removal can also lead to additional disposal costs plus, maintenance may be necessary to remove water-related sludge from the purification systems. There are therefore financial as well operational reasons to test marine fuel for water content via an independent lab.

With so much at stake, test labs need to ensure that they can offer their marine industry clients quick, accurate and reliable approaches for measuring the water content in bunkered fuel. However tests, even those as widely used as the Karl Fischer titration, are not straightforward.

Petroleum products are mixtures of long-chain hydrocarbons that don’t readily dissolve in methanol. Water determination using Karl Fischer titration therefore needs the addition of a solubiliser. Importantly, fuel oils are heterogeneous so any water content will be unevenly distributed so samples therefore need to be homogenised prior to testing.

Also, as a result of the low levels of water, it is important to use a titrant with a low factor – 1 or 2 mg/mL. To complicate things further, fuel additives can trigger side reactions during the titration process. Labs therefore need to ensure that they have reliable access to high quality solubilizers and reagents, ideally from a supplier that can also provide technical support and help with methods.

A backdrop of depressed freight rates, when combined with costly fuel changes, will undoubtedly see many vessel operators chasing the cheapest possible fuel options – a purchasing decision that contains potentially costly risks.

The problem of unscrupulous resellers bulking out deliveries with water, over the permitted limit, is not new. However, at a time of reduced profitability it is essential that vessel operators aren’t paying for water adulterated fuel.

Fuel testing is therefore about to get even more important for the marine industry and labs that offer quick and accurate results will have the potential to maximise the opportunities this will create.

Michael Jeitziner is global marketing manager, Honeywell Research Chemicals