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Intergr8 Fuels: Should the industry worry about decreasing VLSFO viscosity?

Decreasing VLSFO viscosity affects pour points, resulting in wax sludge and other handling difficulties, despite the decline in off-spec VLSFO cases, finds analysis.
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[vc_row][vc_column][vc_column_text]Integr8 Fuels, the bunker trading and brokerage arm of Navig8, on Wednesday (18 March) published an article outlining the importance of noting VLSFO viscosity when analysing quality; it was written by Anton Shamray, Senior Research Analyst, and shared with Manifold Times:

VLSFO quality remains a headline IMO2020 topic. As suppliers are getting more experienced at producing VLSFO blends, the proportion of off-spec tests has been declining, although certain quality concerns remain. One of these is the reduction in viscosity, which is due to more distillate blending. This has resulted in vessels being required to adjust age old practices in order to handle and consume the fuel and moreover requires a change in tact when procuring bunkers. The choice of fuel is often limited, however checking quality before buying is as important as ever in order to minimise the risk of claims.

Lower off-specs but watch viscosity and associated issues

Up until recently, the main concern with regard to VLSFO quality was the relatively high number of off-specs, compared with the other grades like HSFO and LSMGO, and particularly on the “sensitive” parameters. However, as seen in Figure 1, this is now changing and the share of VLSFO off-specs has been declining.

On the other hand, it was found that it is not always necessary for a fuel to be off-spec to result in quality issues when it comes to storing and consuming it. As the market adjusts to the IMO2020 switch and pricing makes it favourable, more distillates have recently made their way into the VLSFO blending pool. As suppliers are getting more experienced at producing VLSFO blends the proportion of off spec tests has been declining, although certain quality concerns remain.

Figure 2 shows the increase in the share of distillate based VLSFO blends and the associated reduction in viscosity.

Indeed, viscosity dropped globally from around 160cst in early November to around 100cst by March, a drop of over 35%.

At the same time the share of distillate based VLSFO went up from around 20-25% to 35-40%. The viscosity drop has affected most bunker hubs. For example, viscosity in ARA dropped 30cst by March to 100cst and there was a bigger decrease in Singapore, from 170cst down to 90cst, with an even bigger reduction in Malta, from 150cst to 50cst.

The trend of lowering viscosity in combination with other factors is a cause for concern. Viscosity, density, pour point, aluminium and silicon (ALSI), and sediment potential (TSP) require careful assessment when purchasing and consuming the fuel.

While the majority of ports recorded very few off-spec fuels in January, several locations were particularly affected.

Viscosity and Pour Point

In the past the effective purification of HSFO required a temperature of 98 deg. C for any fuel over 180cst. Given that many VLSFO fuels are now well below this viscosity level, the purifier temperature is adjusted lower to achieve 20-24cst viscosity in the purifier (for example 58 deg. C for a 30cst fuel).

However, the new VLSFOs are more paraffinic (waxy) and with a higher pour point than HSFO. Under reduced purifier temperatures such fuels may tend to produce wax sludge, which could cause serious handling difficulties; it could also potentially affect the efficiency of removing particles such as aluminium and silicon to safe levels.

It is also essential to inject VLSFO into the engine at the correct injection viscosity. For very low viscosity VLSFO the temperature to achieve the correct injection viscosity may well be on, around, or in extreme cases below pour point (at which the fuel no longer flows) and the wax appearance temperature. For example, in order to inject a 5cst and +12 pour point VLSFO.

The trend of lowering viscosity in combination with other factors is cause for concern it has to be heated or cooled to 18 deg. C, which is only 6 deg. C above pour point (recommended min. 10 deg. C above pour point). In trying to rectify this by increasing the injection temperature the corresponding fuel viscosity would fall, in effect leaving an impossibly small window to operate in outside of which poor combustion, deposit formation and loss of energy may occur even though the fuel is fully compliant with the contractual specification.

Therefore, some owners may prefer buying VLSFO with a minimum 30cst viscosity for RMD/E/G/K grades where pour point is limited to 30 deg. C maximum. Alternatively, if the fuel available is less than 30cst viscosity, it is recommended to be sold against the RMA 10 or RMB 30 spec for which there is a much tighter 6 deg. C (0 deg. C for the winter spec) limit on pour point.

Density and Viscosity

High density in combination with low viscosity remains a cause for concern for VLSFOs, similar to HSFO due to the possibility of poor or delayed ignition and combustion which can result in engine damage. This is also reflected in high CCAI readings in such fuels. It is important to remember that the 2005 ISO specification does not offer CCAI protection.

Analysing over 15,000 VLSFO test results it was found that TSP (the ability of the fuel to deposit sediment) appears to trend up with a decrease in viscosity (Figure 3). This may be due to distillate blending and where different VLSFO components (paraffinic, naphthenic, aromatic) are mixed together in a blend.

Moreover, given that the hot filtration test is performed at 100 deg. C the effects of lower purification temperature (due to fuel’s low viscosity) on the purifier with regard to wax formation may not be fully identified.

Overall, VLSFO quality seems to be improving with fewer samples tested offspec, however checking quality before buying is as important as ever. The ISO spec sets the upper limit for most parameters and it was found that even with all parameters on-spec, some VLSFOs may be more problematic than others. 

This is not normally the case with HSFO where most parameters vary in a much narrower range and average viscosity, despite dropping slightly recently, is still around 300cst.

When it comes to bunker procurement, Integr8 Fuels provides its customers with full information not only on the price but also on quality, availability and delays. By analysing global trends and changes in quality, Integr8 Fuels are well positioned to help procure quality fuels and minimise the risk of claims.


Source and photo credit: Integr8 Fuels
Published: 19 March, 2020[/vc_column_text][/vc_column][/vc_row][vc_row][vc_column][vc_gallery type=”image_grid” images=”9330,9331″ title=”Additional Information”][/vc_column][/vc_row]

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Legal

“Yangtze Harmony”: The practical effects of enforcing bunkers arbitral awards in Rem

Helmsman says Singapore High Court in The “Yangtze Harmony” [2026] SGHC 3 confirmed that the court can lift a ‘stay’ on in rem proceedings, which were put on hold in favor of arbitration.
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Helmsman expands legal services into IP and Technology, Media and Technology

In shipping law, in rem proceedings are unique as a claim may be brought against the ship itself as a separate legal entity rather than the owner personally. This is what allows a ship to be arrested and used as security for such a claim.

Earlier this year, the Singapore High Court in The “Yangtze Harmony” [2026] SGHC 3 clarified an unanswered question: whether the court can lift a “stay” on in rem proceedings – which had earlier been put on hold in favor of arbitration. The court has now confirmed that it can. This means that if a party wins an arbitration, it can return to court and enforce the award as a judgment against the ship or its judicial sale proceeds.

Multi-disciplinary law firm Helmsman LLC focuses on the significance of the “Yangtze Harmony” judgment in enforcing arbitral awards in rem proceedings:

Written by Arjun and Shakthi 1

MT: How are arbitration claims against ships usually enforced in Singapore?

In shipping disputes, it is common for a claimant to start court proceedings against a ship to arrest the ship as security, even though the dispute is to be decided by arbitration. These proceedings are then stayed, pending the arbitration’s conclusion, while the claim remains secured in the form of (a) the arrested ship, or (b) its sale proceeds, or (c) any alternate form of security (such as a bank guarantee or an insurer’s letter of undertaking).

Ordinarily, arbitration awards are enforceable only against the parties named in the award (i.e. in personam). If a shipowner fails to pay, the award holder must enforce the award against the shipowner. The significance of the Yangtze Harmony judgment is that it allows an award holder to enforce the award directly against the ship which it previously arrested. This is crucial for cases against one-ship companies where the ship (or its sale proceeds) may be the only meaningful asset for recovery.

MT: If a ship is sold, where do bunker claims rank in getting paid?

While the decision makes enforcement easier, it does not affect the priority in which sale proceeds are distributed. In Singapore, judicial sale proceeds generally satisfy claims in an order of priorities. Higher ranking claims such as dues, Sheriff costs and secured claims are paid first.

A claim for bunkers supplied for a ship’s operation or maintenance are typically considered a statutory lien claim, which ranks at the bottom of the priorities ladder. Bunker suppliers are only paid from whatever funds remain and they share this equally with other similar claimants. A bunker supplier may not know what other high ranking claims exist until after the vessel is arrested or sold. If those claims are substantial, there may be little or nothing left to satisfy bunker claims.

MT: Can bunker suppliers improve their chances of getting paid?

The court has the power to alter the order of priorities when it is equitable to do so, but it is rare and requires evidence of exceptional circumstances. Ordinarily, a claim for the price of unpaid bunkers would not meet this threshold.

While the Yangtze Harmony brings welcome clarity to allow enforcement of arbitral awards as in rem judgments, this does not guarantee recovery, given the risk of priorities. Bunker suppliers in particular should carefully assess the likelihood of being paid in the event of a judicial sale before taking steps such as arresting a ship.

 

Photo credit: Helmsman
Published: 17 June, 2026

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Bunker Fuel

Huanghua Port expands bunkering capabilities with dedicated fuel oil terminal

Previously, bunkering vessels serving Huanghua Port were required to replenish marine fuel oil at other ports, including Tianjin, before returning to carry out bunkering operations, often resulting in delays.
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June 16, 2026

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Huanghua Port has strengthened its marine fuel supply infrastructure with the commissioning of its first dedicated, all-weather bunker terminal, a move aimed at improving vessel turnaround times and supporting growing shipping activity at the port, according to China-based news outlets on Thursday (11 June). 

On 9 June, bunker tanker Heng Feng You 165 completed fuel loading operations at the terminal in the Huanghua Port Comprehensive Port Area before proceeding to an anchorage to provide bunkering services to waiting cargo vessels.

According to local authorities, the new facility addresses a longstanding bottleneck in the port’s marine fuel supply chain. 

Yao Meichen, Deputy Director of the Cangzhou Municipal Ocean and Port Administration Bureau said bunkering vessels serving Huanghua Port were required to replenish marine fuel oil at other ports previously, including Tianjin, before returning to carry out bunkering operations, often resulting in delays for vessels awaiting bunkers.

As cargo throughput and vessel traffic have increased in recent years, the absence of a specialised bunker terminal became a constraint on port efficiency. To address the issue, local authorities invested RMB 266 million (USD 39 million) to develop Huanghua Port’s first dedicated marine fuel oil terminal and actively pursued regulatory approvals for both a domestic transfer export bonded warehouse and a liquid bonded storage facility.

The terminal, which entered service at the end of last year, features a dedicated 5,000-dwt berth and storage tanks with a combined capacity of 66,000 cubic metres. It has a designed annual throughput capacity of 820,000 tonnes and primarily handles marine gasoil as well as 120 CST and 180 CST fuel oils.

Authorities said the facility has been operating smoothly since its launch and is capable of ensuring a stable supply of bunker fuel for vessels calling at the port.

The bunkering infrastructure will be further enhanced following approval from Shijiazhuang Customs for the establishment of both the domestic transfer export bonded warehouse and liquid bonded storage facilities. The additions are expected to strengthen Huanghua Port’s ability to provide bunkering services to international-going vessels.

“The commissioning of the marine fuel oil terminal has completely changed the previous situation of off-site fuel supply and ships queuing for fuel, achieving benefits for both bunkering vessels and cargo ships,” said Dong Xianke, General Manager of Cangzhou Bohai New Area Gangkun Marine Fuel Co., Ltd., the terminal’s operator.

 

Photo credit: David Yu from Pixabay
Published: 16 June, 2026

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Methanol

China: Chimbusco takes delivery of new methanol bunkering vessel in Zhoushan

Company says commissioning of “Zhong Ran LV Neng 85” will further enhance its service capabilities in green methanol bunkering in major domestic ports.
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June 16, 2026

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Chimbusco takes delivery of new methanol bunkering vessel in Zhoushan

China Marine Bunker (PetroChina) (Chimbusco) recently took delivery of its first bunkering vessel in China to deliver methanol to dual-fuel ships.

The 8,500-dwt duplex stainless steel chemical tanker Zhong Ran LV Neng 85 was successfully delivered in Zhoushan.

The company said the commissioning of this new ship will further enhance Chimbusco’s service capabilities in green methanol bunkering in major domestic ports and expand its national marine new energy service and support network

During the delivery period, Chimbusco said it focused on safe operations and conducted special training for all crew members of the vessel.

The training covered methanol bunkering operation specifications, prevention of collisions between commercial and fishing vessels, daily vessel reporting, and voyage report filling standards.

Manifold Times previously reported the launching of the bunkering vessel at Taizhou Fangzhen Shipbuilding Wharf in Zhejiang.

The floating out of the ship comes after Chimbusco has obtained methanol bunkering licences for Shanghai Port and Ningbo Port.

Related: Chimbusco launches new methanol bunkering vessel in Zhejiang

 

Photo credit: China Marine Bunker (PetroChina) (Chimbusco)
Published: 16 June, 2026

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