Switching Fuel Oil and the Risk of Loss of Propulsion

Nearly nine months have passed since the 0.1% sulphur limit for marine fuels in designated Emissions Control Area (ECA) was introduced following a tightening of MARPOL Annex VI regulations.  Although the general consensus is that operators are largely sticking to the new protocol, the US Coast Guard (USCG) has reported a number of incidents involving fuel leakages caused by fuel switchovers.  These procedures, intended to ensure compliance, do not always have proper safeguards in place.

Fuel switchover risks

Operators who have not chosen to reduce their sulphur emissions by fitting exhaust gas scrubbers are burning traditional fuel in the open seas and then switching to low-sulphur, lighter distillate fuels while inside ECAs.  Machinery space leakages raise the risk of pollution, engine room fires and possible ‘loss of propulsion’ (LOP).

Earlier this year the USCG reminded vessel operators of the importance of establishing robust fuel oil changeover procedures.  As well as ensuring that the fuel tank has been modified where necessary, there should be adequate supplies of ECA-compliant fuel.

Other factors to be considered by ship operators trading within ECAs include differences in viscosity and flash point between the heavy and light fuels.

Loss of propulsion

Among the most common causes of LOP are problems with:

  • Temperature control – while heavy fuels need to be heated, this is not always the case with the lighter fuels associated with low-sulphur.  During the switchover, fuels are moved through the same systems and the heating can cause a ‘flashing’ of the lighter fuel, turning it to vapour and causing a loss of power in the cylinder.
  • Pumps – existing pumps may be unable to cope with the suction of the less viscous lighter oils.
  • Waxy formations in the fuel lines – these are left by low-grade heavy fuel oil.  When lighter oil is introduced it has a solvent-like effect, dislodging the built-up residues and so clogging up fuel filters.

When modifying boilers (most modern boilers were not designed to burn lighter fuel) it is recommended that the manufacturer of the equipment is consulted.  Other important advice from industry experts includes testing changeover procedures before the vessel enters an ECA and ensuring the crew firstly have access to a detailed fuel changeover manual and, secondly, carry out a proper risk assessment.

In January there was a surge in the number of ships filing a Fuel Oil Non Availability Request to the US authorities, mostly due to vessels not having sufficient supplies of fuel oil in time for the 1st January deadline.  Since then the rate has dropped substantially.  Where there are still reports of lack of compliant fuel it generally relates to routine issues, such as weather delays rather than non-availability in ports.

Parker Kittiwake has built a reputation as a global leader in bunker fuel testing and oil sampling solutions for the marine sector.  For more information call the team today on 01903 731470.