September 7, 2023
In July this year reports started to emerge of issues with fuel delivered in Houston, including engine breakdowns.
On 10 July fuel testing and consultancy specialist VPS announced it had identified a marine fuel contamination issue in Houston. It informed its customers and the wider market of the presence of dicyclopentadiene (DCPD) isomers at significantly high levels within VLSFO bunker fuel deliveries in Houston.
The specific contaminants were chemical CAS numbers 4488-57-7 and 6004-38-2 and were detected by VPS using in-house GC-MS (Gas Chromatography – Mass Spectrometer) analytical methodologies.
Initially, VPS reported that 11 vessels had suffered operational issues, such as loss of power and propulsion whilst at sea. These effects resulted from fuel leakage in the injection control units (ICU) and fuel pumps not being able to develop the required fuel pressure, affecting only the auxiliary engines and not main engines. The contaminated VLSFO had been delivered in Houston, by one single fuel supplier.
In mid-August VPS said that a total of 14 had received the contaminated fuel and suffered some form of damage to their auxiliary engines and fuel delivery systems. Twelve of the vessels received their fuel in Houston, while a further two had taken it on in Singapore, with the fuel delivered by four suppliers.
DCPD’s are unsaturated chemical compounds which can polymerise and oxidise under certain conditions. However, the rate of this polymerisation process can be reduced by the presence of inhibitors that are typically found within fuel oil.
Should these compounds start polymerising, the fuel begins to exhibit a level of stickiness and become more viscous, making it difficult for moving components, such as fuel pump plungers and the fuel injector spindles to move freely. These effects cause damage to the fuel injection system. Over a period of time excessive sludge formation is likely to be experienced.
According to VPS, the DCPD compounds that were detected in this fuel ranged from 3,000 to 7,000 ppm (0.3-0.7%) per delivery. VPS employed its own proprietary GCMS Vacuum distillation methodology to detect DCPD, in preference to the ASTM D7845, Standard Test Method for Determination of Chemical Species in Marine Fuel Oil by GCMS. VPS explained that its methodology can detect and measure the DCPD and its isomers, whereas the ASTM D7845 methodology is limited to detecting only 29 chemical contaminants, which does not include DCPD species.
In addition to the 14 vessels suffering damages from burning this fuel, a further 18 vessels that received the contaminated fuel from 13 additional suppliers, either witnessed no adverse reactions, or simply did not provide any feedback regarding any damage.
In total, the volume of contaminated fuel delivered to the 32 vessels, was 61,494 tonnes.
Three vessels de-bunkered the contaminated fuel prior to burning, following a ‘caution’ result from the VPS Chemical Screening service. A further three vessels de-bunkered the fuel after suffering initial engine damage from burning the fuel. However, another two vessels burnt the fuel in their main engines without issue after switching it from their auxiliary engines, where it had caused operational damage.
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