FOBAS Bulletin: Chemical Contamination and Operational Problems, Istanbul

by FOBAS
Tuesday April 29, 2025

In recent days, FOBAS has tested fuel samples from different vessels that have reported problems with fuel injection equipment seemingly caused by a substance sticking and seizing the jerk type fuel pumps. These vessels bunkered fuel in March and April this year from Istanbul.

These fuels have been further investigated with extended chemical analysis showing a number of chemical species present with some at very high levels.

Various chemicals were found including 4-Cumyl Phenol and Cyclohexane Diol at high levels. Resin acids and Acrylates were also identified along with unusually high levels of DCPD (Dicyclopentadiene), Indene and trace levels of Tetrachloroethylene.

Not all these chemicals may be contributing to the problems, but they are in a pattern seen in some problem fuels from Antwerp and Rotterdam in 2024 and a number of problem fuels from Houston in 2023 and 2018. Some of these chemicals can polymerise and are used in the manufacture of resins and plastics and may be reacting together under the heat and pressure of the fuel injection system.

These fuels were found to be on-spec based on standard routine analysis. However, there are some particular parameters of note. Viscosity was low at around 40cSt, acid numbers were high (1.50 – 2.50mgKOH/g) and all fuels were VLSFO with sulphur content <0.50%. This low viscosity and high acid number pattern aligns with other contaminated fuels seen in Houston in 2023).

We would suggest that if you have bunkered in the last 2-3 months in Istanbul to be particularly cautions with the use of the fuel. In particularly if the fuel has a low viscosity, around 50cSt or lower, high acid number >1.00mgKOH/g or high sediments, we would suggest to discuss further testing options as this problematic fuel may not be isolated to only two vessels.

It should also be noted and suppliers reminded that any fuel purchased against the ISO8217 standard must meet the general requirements of clause 5 as well as limits in the characteristics tables. Clause 5 includes the statement that the fuel should be a “homogeneous blend of hydrocarbons derived from petroleum refining” and be free from any substance or chemical waste that “jeopardizes the safety of the ship or adversely affects the performance of the machinery”.

Please let us know if you would like further information or if you have concerns over any particular fuel.

If you require any further information about this Bulletin, please contact us at fobas@lr.org or speak to one of our consultants on +44 (0)330 414 1000 (Southampton UK), +44 (0)1642 440991 Redcar (UK), +65 3163 0888 (Singapore), +30 211 990 7732 (Greece). For anything urgent, please contact us via our out of office number, +44 (0)1642 425660

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