Bunker fuel testing and marine surveying business Maritec-Naias on Friday (7 August) issued an alert regarding high levels of Phenolic compounds found after conducting testing on multiple fuel oil bunker samples from China ports:
During the period of 07 June to 28 July 2026 Maritec-Naias tested multiple fuel oil bunker samples from vessels that took fuel/bunkered in China ports, which indicated the presence of high levels Phenolic compounds.
Ten cases were found to have Phenolic compounds, and its derivatives, in the range of 5200 – 15750 PPM. Out of ten cases, the fuel samples tested were sourced as follows: four from Tianjin port, two from Qinhuangdao port, two from Rizhao port, one from Zhoushan port, and one from Shandong port.
The fuel samples containing Phenolic compounds in excess of 5000 PPM returned a marginally stable classification (P-value 1.00 to <1.30) under the SMS 1600 stability reserve test. Prolonged storage of these fuels carries the risk of reduced fuel stability and resulting operational issues. Operational issues like excessive sludge formation in purifiers, filter choking and fuel pump wear-and-tear have been observed and reported when similar levels of phenolic compounds were present in a vessel’s bunker fuel.
Phenolic compounds in the bunker fuel samples were precisely identified using Gas Chromatography-Mass Spectrometry (GC-MS) with both Direct Liquid Injection (DLI) and Solid Phase Extraction (SPE) methods, ensuring robust detection. The detected chemical compounds may have originated from the following sources:
1) liquid fuels derived from coal-tar
2) shale-derived oil
Regulatory Implications:
Due to the high levels of these chemical compounds the fuels render unacceptable under the section of general requirement in the standard ISO8217:2010 and MARPOL Annex VI regulation 18, irrespective of Table 2 compliance.
General requirements as per para 5 of ISO8217:2010 states below:
“5.2 The fuel shall be homogeneous blends of hydrocarbons derived from petroleum refining. This shall not preclude the incorporation of small amounts of additives intended to improve some aspects of fuel characteristics and performance. The fuels shall be free from inorganic acids and from used lubricating oils.
5.3 The fuel shall be free from any material that renders the fuel unacceptable for use in marine applications.
5.5 The fuel shall not contain any additive at the concentration used in the fuel, or any added substance or chemical waste that
- a) jeopardizes the safety of ships or adversely affects the performance of the machinery; or
- b) is harmful to personnel; or
- c) contributes overall to additional air pollution.”
MARITEC-NAIAS RECOMMENDATIONS
- Closely observe the vessel fuel system/s for signs of filter clogging and purifier sludging and additionally, increase vigilance on the centrifuges to monitor overloading.
- Increase frequency of their de-sludging cycle depending on the accumulated sludge.
- Possibly reduce the mean time between bowl cleaning of the purifier and fuel system filters.
- Avoid blending with other fuels, in particular marine diesel and gas oil and also other fuel oil as such mixing may well increase the sediment problem.
Photo credit: Louis Reed from Unsplash
Published: 12 August, 2026
