ExxonMobil: Best Practices for Low-Sulfur Fuel

Freighter takes on bunkers (File image)

Published Jun 28, 2018 2:42 PM by ExxonMobil Insights

The fuels landscape is set to dramatically change when the International Maritime Organization’s (IMO) 0.5 per cent sulfur cap comes into force on 1 January, 2020. Ahead of this, ExxonMobil has developed a set of tips to help the marine industry switch to low sulfur fuels while maintaining a vessel’s safe and reliable operation.


First, establish best practice

Prevention is always better than cure, so it is advisable to:

- Buy fuel that meets the latest ISO 8217:2017 specification

- Only bunker from reputable fuel suppliers

- Clean out bunker tank residues when necessary


Test for cat fines

Some new 0.5 per cent sulfur fuels could contain elevated levels of cat fines which, if not properly treated, could trigger catastrophic engine damage. If laboratory testing shows a high concentration, then:

- Maintain storage tank temperatures at least 18°F above fuel pour point

- Keep settling tanks at 185°F

- Operate purifiers at optimum efficiency and minimum throughput

- Drain water from fuel tanks to aid settling


Check for compatibility

There is a risk that two compliant fuels will not be compatible, which can trigger sludge formation. It is therefore essential to:

- Test the fuels for compatibility, ideally in a laboratory.  If the fuel is already loaded, then test onboard to get immediate results

- Store fuels separately until testing has been carried out

- Even when two fuels are compatible, avoid mixing in excess of 80:20


Monitor for sludge

If sludge does start to form, it is essential to ensure against further fuel blending before any remedial action is taken, as this may exacerbate the problem. Then:

- Operate two or more separators in parallel at their lowest throughput

- Increase the frequency of purifier discharge

- Monitor and clean filters frequently


“With so many different types of fuel potentially set to enter the bunker market, vessel operators are rightly concerned about stability, compatibility and quality issues, such as elevated levels of cat fines,” said John LaRese, Marine Fuels Technical Advisor, ExxonMobil. “It will therefore be more important than ever for operators to follow best practice when bunkering compliant fuels, including using laboratories to test fuel samples for potential issues.”

The opinions expressed herein are the author's and not necessarily those of The Maritime Executive.