Fuel testing agency Maritec-Naias has issued a warning regarding elevated levels of phenolic compounds detected in bunker fuels lifted at several Chinese ports, one of the world's largest bunkering markets where ports such as Zhoushan rank among the top global suppliers by volume.

In its latest Bunker Flash alert issued on August 7, the firm reported that samples collected from vessels that bunkered in China between June 7 and July 28 revealed ten cases containing phenolic compounds and their derivatives at concentrations ranging from 5,200 to 15,750 ppm.

The affected samples were sourced from five locations: four from Tianjin, two from Qinhuangdao, two from Rizhao, one from Zhoushan, and one from Shandong.

According to Maritec-Naias, samples with phenolic content above 5,000 ppm returned only a marginally stable classification, recording P-values between 1.00 and below 1.30 under the firm's stability reserve test. The P-value is a measure of a fuel's reserve stability — its capacity to remain stable under storage and use without precipitating sediments. The agency cautioned that prolonged storage of such fuels risks further degradation of stability.

When similar concentration levels of these compounds have been present in bunker fuel, operators have observed excessive sludge formation in purifiers, filter choking, and accelerated fuel pump wear, the firm noted. Such operational problems can lead to engine performance issues and, in severe cases, propulsion loss — a concern the shipping industry has tracked since major fuel contamination events, including the widespread 2018 Houston bunker contamination incident that affected hundreds of vessels.

The compounds were identified using gas chromatography-mass spectrometry analysis. Maritec-Naias indicated that they may have originated from liquid fuels derived from coal tar or from shale-derived oil — non-traditional refinery or chemical feedstocks that can enter the bunker supply chain through blending of cutter stocks or off-specification intermediate streams.

The testing firm argues that the presence of these contaminants renders the fuels unacceptable under the general requirements of ISO 8217 and MARPOL Annex VI Regulation 18, regardless of whether the fuel complies with the standard's Table 2 parameters. ISO 8217 is the international standard governing marine fuel specifications, and its general requirements stipulate that fuels must be free from inorganic acid and additional materials that could harm machinery. MARPOL Annex VI Regulation 18, part of the IMO's marine pollution convention, places obligations on fuel oil quality and availability for ships.

Maritec-Naias advised affected vessels to closely monitor fuel systems for filter clogging and purifier sludging, increase de-sludging frequency, and refrain from blending the fuel with other products — particularly marine diesel and gas oil — as mixing may exacerbate sediment formation.

The agency also noted that while its findings are accurate, they should not be taken as reflective of the overall quality of bunker fuel supplied across China.

Source: Ship & Bunker