• Maritec-Naias finds phenolic compounds at 5,200-15,750 ppm in ten samples from China bunkerings
• Cases traced to Tianjin, Qinhuangdao, Rizhao, Zhoushan, and Shandong
• Affected fuels only marginally stable, risking sludging, filter choking, and pump wear
• Testing firm says levels render fuels off-spec under ISO 8217 regardless of Table 2 compliance

Fuel testing agency Maritec-Naias has warned of elevated levels of phenolic compounds in bunker fuels lifted at Chinese ports.

Samples from vessels that bunkered in China between June 7 and July 28 revealed ten cases with phenolic compounds and their derivatives at concentrations of 5,200 to 15,750 ppm, the firm said in its latest Bunker Flash alert issued on August 7.

Four of the samples were sourced from Tianjin, two from Qinhuangdao, two from Rizhao, one from Zhoushan, and one from Shandong.

Samples with phenolic content above 5,000 ppm returned only a marginally stable classification, with P-values of 1.00 to below 1.30 under the firm's stability reserve test, and prolonged storage of such fuels risks reduced stability.

Excessive sludge formation in purifiers, filter choking, and fuel pump wear have been observed when similar levels of the compounds were present in bunker fuel, according to the firm.

The compounds, identified by gas chromatography-mass spectrometry, may have originated from liquid fuels derived from coal tar or from shale-derived oil, Maritec-Naias said.

The firm argues the contamination renders the fuels unacceptable under the general requirements of ISO 8217 and MARPOL Annex VI Regulation 18, irrespective of compliance with the standard's Table 2 parameters.

Affected vessels are advised to monitor fuel systems closely for filter clogging and purifier sludging, increase de-sludging frequency, and avoid blending the fuel with other products, particularly marine diesel and gas oil, as mixing may worsen sediment formation.

Maritec-Naias noted that while its findings are accurate, they do not reflect the overall quality of fuel supplied in China.