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VPS: Why do VLSFOs still require quality considerations?

VLSFO play an important role, comprising 55% of marine fuel samples; while no official ISO8217 specs exist, VLFSOs demand careful management due to unique properties.

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Steve Bee, Group Commercial & Business Development Director of marine fuels testing company VPS, on Thursday (18 August) shared that in the pursuit of greener shipping, the shipping industry should not overlook the importance of quality fuel management for traditional fossil fuels. 

Very Low Sulphur Fuels (VLSFO) play an important role, comprising 55% of marine fuel samples. While no official ISO8217 specs exist, VLFSOs demand careful management due to unique properties:

As the world of shipping quite rightly focuses on reducing its carbon footprint and endeavours to comply with a host of decarbonisation legislation, it may be easy to forget that traditional fossil fuels are still the main energy source for the majority of the global fleet. As such, the fuel management of fossil fuels and their quality, continues to be an important factor in protecting vessels, their crew and the environment.

As the most widely used fossil fuel, Very Low Sulphur Fuels (VLSFOs) require more focus than others, in terms of their fuel management. VLSFOs currently account for 55% of all marine fuel samples received by VPS for fuel quality testing. There are still no official standard specifications within ISO8217 for VLSFOs.

As such, most VLSFOs are tested against the RMG380 specifications, knowing that the viscosities of VLSFOs in particular, are very much lower than 380cSt. Currently, 68% of all VLSFOs tested have a viscosity between 20cSt-180cSt. This can have a significant impact on the transfer and injection temperatures onboard a vessel, requiring much less heating of the fuel to achieve the optimum injection viscosity. It would be beneficial to see the introduction of a minimum viscosity specification limit for VLSFOs, as well as a current maximum viscosity limit within ISO8217?

Currently 3.8% of all VLSFOs tested have at least one off-specification parameter. This compares favourably with the off-specification rates for HSFO fuels at 11.4% and MGO fuels at 16.9%. However, the VLSFO off-specifications are potentially more concerning than some of those associated with HSFO and MGO. Sulphur, water, cold-flow properties and cat-fines are the most frequent of VLSFO off-specification parameters.

Screenshot 2023 08 21 at 1.47.56 PM

Sulphur off-specification is the most common of all VLSFO off-specifications, with over 30% of all off-specifications being attributed to this one parameter. However, recent test results have shown that sulphur off-specification is certainly better today than it was back in 2021, with only 1.6% of VLSFOs tested being >0.50% Sulphur compared to 2.4% >0.50% in 2021.

Also, it would appear that so far this year, suppliers are producing more fuel in the 0.41%-0.46% Sulphur range, than the 0.47%-0.50% range, than over the past two years, which means that there is less chance of the VLSFOs falling outside of the 95%-confidence interval, or being off-specification.

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Due to the higher level of paraffinic content of VLSFOs over HSFO fuels, it is more likely to see wax precipitation occur with VLSFOs, when subjected to colder temperatures.

The formation of wax crystals during storage and consumption is a potential major source of operational problems with VLSFOs. Therefore, it is vitally important to test for wax appearance (WAT) and wax disappearance temperatures (WDT), as the pour point of the fuel is not a reliable indicator of potential cold-flow issues.

During 2019, VPS developed a proprietary test to be able to measure both WAT and WDT in VLSFOs, which many of our customers have become reliant upon to safeguard their vessels from wax precipitation and it’s potentially damaging consequences.

Current global averages show VLSFO Pour Point is 16°C, whilst the average WAT is 38°C, and the average WDT is 48°C. These figures illustrate why using +10°C above the pour point as an indicator of the cold-flow properties of VLSFO blends is simply insufficient, as well as inappropriate as a risk mitigation measure.

When WAT and WDT results are high, vessels need to consider raising the temperatures of their onboard separators, as well as the temperatures within storage, settling and service tanks.

However, VLSFOs with a short shelf life and high WAT may not be suitable for storing, as heating such fuel accelerates the ageing process and increases the likelihood of fuel sludging.

VLSFOs with low viscosity but high WAT & WDT, need to be heated to ensure a stable flow and to prevent wax formation. Such fuels will likely need to be cooled before entering the main engine, due to their low viscosity. This could present operational issues such as wax formation when the fuel temperature drops below the WAT.

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Stability issues relating to VLSFOs have been a concern since their introduction in 2019. To this day we still witness spikes in Total Sediment Potential (TSP) across the world.

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Some VLSFO blends appear stable on bunkering but become unstable over time (within a week or two). Heating the fuel in the tanks (to maintain suitable storage and transfer) and purifiers (to achieve efficient purification) deteriorates the fuel’s stability and fastens the ageing process. 

VLSFOs that are incompatible can cause separator sludging and clogging of filters. As such, numerous vessels have witnessed incompatibility issues when the vessels change from MGO to VLSFO or (vice versa). 

VLSFOs with high WAT/WDT and high cat-fines create a need to operate separators at higher temperatures, at shorter discharge intervals. When this is practice is undertaken, wax starts to form, affecting purifier operation as well as clogging the fuel system’s filters. 

Finally, regarding stability, VLSFOs with high WAT/WDT, that also have chemical contamination, followed by low viscosity, will unlikely to be handled on-board of vessels. In such cases, the only solution is to de-bunker the fuel. 

Between Feb-July 2023, VPS detected contamination in VLSFO fuels in Houston. This contamination saw the presence of two specific isomers of Dicyclopentadiene (DCPD) at concentrations between 1,000ppm-40,000ppm. 

The specific isomers were: 

  • Di-hydro dicyclopentadiene Chemical CAS Number: 4488-57-7 
  • Tetra-hydro dicyclopentadiene Chemical CAS Number: 6004-38-2 

DCPD’s are unsaturated chemical compounds which can polymerise and oxidise under certain conditions. When DCPD polymerises, the fuel begins to exhibit a level of stickiness and becomes more viscous, making it difficult for moving components, eg fuel pump plungers & 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. 

This specific case saw 12 vessels which bunkered the fuel in Houston suffer major operational issues and damages to auxiliary engines & fuel delivery systems, from fuel supplied by 4 suppliers. The type of problems witnessed were fuel leakage in the ICU (Injection Control Unit) units and fuel pumps not being able to develop the required fuel pressure.

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In order to mitigate the risks associated with chemical contamination of VLSFOs, VPS recommend their GCMS-HS Chemical Screening service with each VLSFO bunkering. This service is a pre-burn, rapid, low-cost test, which can identify the presence of volatile chemicals within VLSFOs such as styrene, DCPD and chlorinated hydrocarbons, to name but a few and provide an elevated level of protection to the vessel. 

To summarise, VLSFOs as the most widely used marine fuel powering today’s global fleet, can potentially create numerous operational and compliance issues, due to their varying quality. In order to mitigate the potential risks caused by, poor cold-flow parameters, fuel stability, chemical contamination, low viscosity and sulphur non-compliance, effective fuel management and testing can certainly help reduce and even eliminate such risks.

Related: VPS identifies new bunker fuel contamination at Houston
Related: FOBAS: Possible bunker fuel contamination in Houston and US Gulf area
Related: Viswa Group gives update on bunker fuel issues in Houston
Related: FuelTrust analysis finds fuel content discrepancies in 39% of global bunker deliveries
Related: VPS: Houston contaminated VLSFO bunker fuel was also supplied in Singapore
Related: BREAKING: Vessels supplied in Singapore yet to report engine issues due to contaminated bunkers, following Houston VLSFO case

 

Photo credit: VPS
Published: 21 August, 2023

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Biofuel

Singapore: Sea Oil Petroleum receives ISCC EU certification, mulls increasing product portfolio

‘Sea Oil seeks to do its part for climate change by giving options to support to our end users,’ says Steve Goh, Head of Trading.

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Singapore-based bunker trading firm Sea Oil Petroleum Pte Ltd (Sea Oil), a wholly owned subsidiary of Thailand-listed Sea Oil Public Company Limited, has received International Sustainability and Carbon Certification (ISCC) EU certification, learned Manifold Times.

ISCC EU is a certification scheme that verifies compliance with the sustainability criteria for biofuels and bioliquids within the European Union. It ensures that biomass and biofuels used in the EU meet specific environmental and social requirements, including greenhouse gas emission reductions and traceability throughout the supply chain.

The milestone, which took place on 22 May after two months of processing, was reflective of the company’s aim to expand its bunker fuel product offerings to clients seeking sustainable solutions, Steve Goh, Head of Trading at Sea Oil, told the bunkering publication.

“It is important for the bunkering sector to remain relevant, adapt, and play an active role in supporting shipping’s decarbonisation journey,” said Mr Goh while adding that, “this is in line with our group’s green initiative and sustainability drive.”

“As such, Sea Oil seeks to do its part for climate change by giving options to support to our end users.

“By achieving ISCC EU certification, Sea Oil will be in a better position to provide green marine fuel solutions to customers embarking on this journey towards net zero.”

Manifold Times in May reported Sea Oil welcoming a Senior Bunker Trader to its team.

The company started 2025 with an expanded team on both international and local fronts.

Sea Oil Petroleum may be reached at: [email protected]

Related: Singapore: Sea Oil Petroleum boosts Asia and international presence with new Senior Bunker Trader
Related: Singapore: Sea Oil Petroleum enters 2025 with international representatives, expanded team

 

Photo credit: Sea Oil Petroleum
Published: 10 July 2025

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Wind-assisted

Anemoi unveils state-of-the-art rotor sail production facility in China

Site boasts an annual production capacity of 250 Rotor Sails, and the option to expand further and store units for fast turnaround.

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Wind propulsion solutions provider Anemoi Marine Technologies on Tuesday (8 July) officially opened its new Rotor Sail production facility in China.

Strategically located on the banks of the Yangtze River, Anemoi’s facility is located in Jingjiang City, Jiangsu Province, within Daming Heavy Industry’s manufacturing base.

The facility provides direct access to port infrastructure, enabling seamless logistics for import, export, and delivery.

With barge transport available on-site, Rotor Sails can be transported efficiently and installed directly at nearby major shipyards, streamlining operations and minimising environmental impact.

“This is more than just a new site,” said Clare Urmston, CEO of Anemoi.

“It’s a fully integrated, end-to-end production hub where every stage, from steel fabrication and precision assembly to rigorous testing and quality assurance, is handled under one roof.

“That means faster turnaround, uncompromised quality, and complete oversight by our expert team, on site, from start to finish. Anemoi’s strategy is quality first and this site enables exactly that.”

With an annual production capacity of 250 Rotor Sails, and the option to expand further and store units for fast turnaround, the new site positions Anemoi to meet surging global demand and support its customers in achieving critical decarbonisation goals.

 

Photo credit: Anemoi Marine Technologies
Published: 10 July 2025

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Milestone

Global Energy Storage Group sells Rotterdam terminal to Tepsa, exits Dutch market

Chooses to sharpen its focus on growth in Asia, particularly its flagship terminal in Port Klang, Malaysia.

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Global Energy Storage Group (GES) on Wednesday (9 July) announced the completion of the sale of its terminal located in the Port of Rotterdam., marking its exit from the Dutch market.

The facility, which includes 212,000 m³ of tank storage and approximately 18 hectares of development land in the Europoort area, was sold to Tepsa, a European bulk liquid and gas storage operator.

The transaction represents a key milestone for GES as it continues to focus its resources on expanding its presence in the fast-growing Asian market, with particular emphasis on its strategic terminal at Port Klang, Malaysia.

It also ensures that the Rotterdam terminal is passed into the hands of a high-quality follow-on owner well positioned to take the asset forward. The transaction also delivers a strong return for GES’s shareholders.

“Part of the investment cycle is realising value from assets at the right time, and we’re confident this was the right moment for GES,” commented Peter Vucins, CEO of GES.

“We are now fully focused on growing our business in Asia, with Port Klang at the centre of that strategy. We extend our sincere thanks to the Rotterdam team and our customers for their support and for maintaining a safe, reliable, and forward-looking operation throughout our ownership.”

With the sale of the Rotterdam terminal, GES no longer holds assets in the Netherlands.

 

Photo credit: Global Energy Storage Group
Published: 10 July 2025

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