VPS Identifies Houston Fuel Contamination

VPS, a leading global marine decarbonisation advisory services company, has identified via its fuel testing services, a new marine fuel contamination issue in Houston.

VPS detected the presence of Dicyclopentadiene (DCPD) and associated isomers at significantly high levels in VLSFO bunker fuel deliveries in Houston. These chemical contaminants were detected using in-house GC-MS (Gas Chromatography – Mass Spectrometer) analytical methodologies. VPS has issued a Bunker Alert to its customers referring to these fuel deliveries made by a single supplier during the months of March to May 2023. Problems associated with these bunkers occurred after this fuel was combusted several weeks after bunkering.

Eleven vessels using this fuel have now reported loss of power and subsequent loss of propulsion whilst at sea. These effects resulted from fuel leakage in the ICU (Injection Control Unit) units and fuel pumps not being able to develop the required fuel pressure. Both main and auxiliary engines were affected although failures to auxiliary engines were more commonly reported.

One VPS customer highlighted the issues they encountered when using this Houston VLSFO: the first sign of problems after changing over to this fuel was the failure of the fuel pump and fuel injectors of the auxiliary engines. All the three auxiliary engines subsequently faced the same issues and was unable to produce the required power resulting in a complete blackout and loss of propulsion. The auxiliary engine pumps exhibited significant leakage and the fuel injectors were ceased. Both, fuel pumps and fuel injectors required repeated replacement until no spares remained.

This customer also reported that this fuel had a significant impact on the purification system. It was noted that the purifiers could not remove the high cat fines that were present in the fuel under normal engine operating speed. To keep the purifier operational, main engines required running at low rpm than normal, to reduce the fuel consumption thereby reducing the purifier feed-rate.

Due to restrictions in power, the vessel had restricted manoeuvrability as they could not operate their thrusters. The vessel had to change to LSMGO (Low Sulphur Marine Gas Oil) to arrive safely to the port.

Figures Showing sludge formation in filters (left) and ceased fuel pump plunger (right). Image Credit: VPS

DCPD's are unsaturated chemical compounds which can polymerise and oxidise under certain conditions. However, the rate of this polymerisation process can be reduced by the presence of inhibitors that are typically found within fuel oil.

Should these compounds start polymerising, the fuel begins to exhibit a level of stickiness and become more viscous, making it difficult for moving components, such as fuel pump plungers and the fuel injector spindles to move freely. These effects cause damage to the fuel injection system. Over a period of time excessive sludge formation is likely to be experienced.

The DCPD compounds that were detected in this fuel ranged from 3,000 to 7,000 ppm (0.3-0.7%). A number of vessels had been pre-warned by VPS of the potential high-concentration DCPD contamination of their fuel, via a "Caution" result from the VPS Chemical Screening service, highlighting the value of this pre-burn service provided by VPS.

For further information regarding VPS chemical contamination detection services contact, Steve Bee, Group Commercial & Business Development Director: steve,bee@vpsveritas.com.