Marine insurer Skuld has issued an advisory after several vessels reported bunkering fuel in Southeast Asia that met ISO 8217 parameters but later showed unusually high concentrations of chemical compounds during advanced testing.

Most of the affected stems were supplied in Singapore, Hong Kong and Malaysia, Skuld noted. Gas chromatography-mass spectrometry (GCMS) results showed a high presence of hydrocarbon compounds, phenolic compounds and alkylresorcinol derivatives, with findings resembling those reported by fuel testing laboratories in connection with shale oil components.

Some GCMS reports reviewed by the insurer showed dihydro-dicyclopentadiene and indene concentrations of between 5,000 ppm and 14,000 ppm, while alkylresorcinol levels ranged from 4,700 ppm to 6,000 ppm.

Skuld observed that shale oil is not regarded as a contaminant and is an acceptable blend component under ISO 8217. However, elevated concentrations can create onboard challenges, as these substances are not typical of marine fuels.

The insurer cautioned that such content may lead to sludge formation, purifier and filter fouling, fuel injection problems and poor engine performance, although it added that most ships using these fuels do not experience difficulties.

Skuld also noted that when GCMS is conducted as part of a troubleshooting exercise following reported machinery problems, a link can be established between the detected substances and the issues encountered. It added that fuel containing added materials or chemical waste that jeopardises ship safety, harms machinery, affects crew welfare, or contributes to additional air pollution would not comply with Clause 5 of ISO 8217.

The advisory also recalled similar cases seen in 2019, when a number of very-low-sulphur fuel oil (VLSFO) stems from the Amsterdam-Rotterdam-Antwerp (ARA) region contained these substances at very high levels.

Skuld advised members and assureds to carry out due diligence when procuring bunkers, vet suppliers carefully, seek clarification on blended components and test fuels before use. It also recommended extended GCMS analysis by a reputable fuel laboratory, close monitoring of onboard treatment equipment, including purifiers and filters, good record keeping and fuel system checks to verify the quality of fuel entering the engine.