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Is the gradual rise in Off-Spec VLSFO due to Sulfur content, avoidable?

The number of off-spec VLSFOs due to sulfur dwarfs other causes, but it doesn’t seem logical to prepare a fuel that is only slightly off-spec, notes Francisco Malta.

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Francisco Malta of VM Industrials, the official distributor for Aderco in Oceania, on Sunday (11 October) published an article on the possible reasons behind off-spec VLSFO due to minor, but decisive, deviations in sulphur content:

Some VLSFOs can be and may become off-spec over time due to total sediment potential, water content, pour points, cat fines, and flashpoints. These are all explicable.

However, the number of VLSFO off-spec due to their sulfur content is extraordinarily high in proportion to other causes and this doesn’t seem logical.

Veritas Petroleum Services (VPS – a lab with 50% of the global market share in bunker sampling), recently published its 10th edition of VLSFO Insights. VPS reported that global VLSFO off-spec samples had increased from 5% to 7% between July 2020 and August 2020, with sulfur content above regulation remaining the number one culprit and not by a small margin. The number of off-spec VLSFOs due to sulfur contents dwarfs all other causes by two, if not three times.

The margins making the sulfur values off-spec are small and often only slightly above the limits permitted. As the IMO rules don’t have much wiggle room, simply crossing that 0.50%-0.53% threshold for supplier and customer may result in fines, costly de-bunkering, and delays.

It doesn’t seem probable for a VLSFO blender producer to go through the trouble of preparing a fuel that is only slightly off-spec, most often by as little as 1, 2, or perhaps 3 percent above 0.50% limit.

This is the one variable in the production that should be under control and not affected by laboratory error or the challenges in the blending compatibilities between feedstocks. These are automated computerised blending programs calculating which feedstocks and sulfur values are required to deliver a compliant fuel.

Probable cause.

One element a computer cannot factor is whether there is already residue left from other blends in the storage tanks. Presuming the blending program begins its calculations from zero and assumes the blending and storage tanks are empty. Clearly, this is rarely the case and often there is a growing percentage of residue at the bottom of all tanks that will continue to accumulate in time unless it is removed and cleaned after each batch.

The larger and heavier hydrocarbons chains contain the most sulfur, hence, this is why producers blend heavier fuels with lighter paraffinic feedstocks to achieve the mandated lower sulfur levels.

Over time some of these heavier hydrocarbons will drop by aggregation (TSP) and gravity to the bottom of the tanks. If this is the case, then logically the residues in the tanks will gradually have a higher sulfur content than the fresh feedstock or VLSFO blends being introduced.

This residue is something the blending programs may not factor in.

Thinking about this further, it may be happening throughout the entire supply chain all the way to the ship and its tanks.

As time goes on and the percentage of higher sulfur residue increases in all tanks. A possible scenario could be;

  • Where a supplier’s older barge receives a 0.50% S VLSFO and bunker a 0.52% S VLSFO to the customer, simply due to the commingling of the residue with higher sulfur left in its tanks. Whereas the supplier’s newer barge may be bunkering that very same fuel with 0.50% S to another ship, as its tanks are clean and without any residue from other bunkers.

Or another where;

  • Perhaps a ship’s tank has fuel residue from previous bunkers, and possibly enough to impact a fresh batch of bunkered fuel. Again, possibly resulting in an increase in sulfur content above the IMO limit that also differs from the supplier’s Bunker Delivery Note.

Both these scenarios could leave the supplier and the customer in a predicament situation with neither knowingly at fault.

The complexity of the VLSFO supply chain.

VLSFO producers could potentially adjust for a higher margin of error, for instance, produce a 0.40% S fuel, and perhaps some already do some type of adjustment.

However, producing these fuels is not only costly, but it is also competitive and even a small fraction of a percentage drop in sulfur in a market of this magnitude equates to a substantial reduction in revenue.

Adeco Malta

If this theory is correct. What is at stake is the inevitable risk in a relationship breakdown between customers and suppliers without real merit or intention on either part.

This rise in the sulfur content would be incremental and anywhere, yet everywhere. After all the supply chain of a VLSFO is a long and complex one with many storages along the way. An example image above.

A further indicator – Cat Fines.

The VPS paper also reported that off-spec VLSFO cases due to cat fines had also doubled between July and August.

Cat fines are hydrophilic by nature and in time drop from suspension by gravity as they trickle down following water droplets entering fuels from the condensation in storages.

Therefore, there is a probability that cat fines are also accumulating in tanks throughout the supply chain and the ship. With every bunker and movement, they will become suspended again and eventually drop, slowly increasing in numbers within the residue at the bottom of the tanks.

Again, possibly leading to a sample mismatch with the Bunker Delivery Note.

If this is the case, then what can be done?

Keeping tanks clean throughout the entire supply chain and all the way to the ship is one method, this could be done through periodic manual cleaning. Another option is the use of chemical additives that maintain the VLSFO homogenised. By inhibiting and releasing the aggregation of hydrocarbons and water, ensuring TSP is controlled and the fuel remains water-free.

Ultimately being able to consistently deliver and maintain the VLSFO sulfur content as it was intended and expected by the producer, the supplier, and the ship would bring benefits to all. By avoiding further disruption in the already challenging and new IMO 2020 environment.

However, as in all business cases, the benefits must outweigh their costs.

Disclaimer; These are VM Industrials’ opinions only and do not reflect the opinions of any other parties. This article intends to prompt discussions on these topics within the bunkering and shipping industry.


Source: Francisco Malta
Photo credit: VM Industrials
Published: 21 October, 2020

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Bunker Fuel

Alkagesta highlights key insights on European choke point pressures in August

Update covers dual supply crisis currently shaping global bunker markets — a stalled Strait of Hormuz peace process and Rhine water levels at a 140-year record low — and the implications for Singapore.

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Malta-based global commodity trading house Alkagesta recently shared latest market insight examining the dual supply crisis gripping global energy markets as diplomatic efforts to reopen the Strait of Hormuz stall and Rhine water levels fall to record lows, creating what the company describes as a “state of emergency” for European inland fuel distribution.

In an article published on Alkagesta Market Insights on 11 August, the company’s trading and market intelligence teams outlined how the convergence of two simultaneous logistical crises is tightening prompt fuel availability across Singapore, Northwest Europe, and the Mediterranean:

Strait of Hormuz transits fell to a near-one-month low of 13 ships on August 9 following an attack on an ADNOC-linked tanker, as both the US and Iran demand war reparations before any reopening agreement can be reached. Simultaneously, Rhine water levels at the Kaub chokepoint fell to 16 cm on August 10 — the lowest since records began in 1880 — with forecasts pointing to a further drop to just 4 cm by August 14, effectively halting barge traffic and trapping fuel oil stocks at the ARA hub.

The supply picture across both key hubs has deteriorated sharply. In Singapore, Middle Eastern fuel oil imports nearly tripled week-over-week to 328,878 mt by July 29 — the highest volume since March — providing some relief as onshore commercial heavy distillate stocks rose to a five-week high of 19.58 million barrels by August 5. However, July bunker fuel sales are estimated to have fallen 3.7% month-over-month to 4.44 million mt, with elevated premiums redirecting prompt demand toward alternative ports including Zhoushan and Port Klang.

In Europe, the VLSFO market remains acutely undersupplied as refiners continue to prioritize high-margin diesel over low-sulfur blending components, while the Rhine crisis has forced barges to operate at just 15–20% of normal capacity — with freight rates from Rotterdam to Karlsruhe rising more than 400% in two months.

Alkagesta’s strategic outlook points to a potential total breakdown in Rhine-linked inland distribution by mid-August, a VLSFO Hi-5 spread likely to remain above $200/mt through Q3, and a global crude market that analysts warn requires an additional 2.1 million b/d for 18 months to rebuild depleted inventories.

Note: The full article can be read here.

 

Photo credit: Alkagesta
Published: 17 August, 2026

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Bunker Fuel

Integr8 Fuels: Why bunker markets could be lower than we thought

Marine fuel prices could prove lower than previously anticipated as easing refinery margins and improving bunker market fundamentals outweigh a still-uncertain crude oil outlook, says Integr8 Fuels.

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By Steve Christy, Expert Contributor, Integr8 Fuels

29 July 2026

We have just seen one false dawn, is there another to come? 

Last month, we wrote about how close we were to the expected lows in Brent and Rotterdam bunker prices, but not yet Singapore. Given what has happened since, a month is not only a long time in politics, but also a very long time in the bunker market. 

There was a resumption of attacks in the Arabian Gulf region on 13 July, followed by targeted Houthi attacks on Saudi Arabia’s Red Sea oil infrastructure and shipping in the Bab el-Mandeb region, the gateway between the Red Sea and the Gulf of Aden. As a result, Brent futures fell to lows of around $70/bbl in late June and early July before surging to a high of $100/bbl on 23 July. Over the same period, Singapore VLSFO fell to $635/mt before climbing to $865/mt, a swing of $230/mt in just 16 days. 

Jul 2026 Graph 01 1024x613 1

Prices at the start of this week fell sharply after a halt in Arabian Gulf attacks over the weekend, with front month Brent was down to intra-day lows of $84/bbl, and Singapore VLSFO $750/mt.  However, at the time of writing there has been a ‘surprise’ attack by Iran, and retaliatory action by the US, with prices rising again.  It looks like we could be at another false dawn. 

The obvious questions are: will there be a return to peace negotiations, and are we close to the end of the war and free-flowing traffic through the strait of Hormuz (and also the Bab el-Mandeb)? The obvious answer is, we don’t know; there are only a few people that are likely to know the answer to this. All we can do is plan for every eventuality. 

Low stocks, higher bunker prices, and a strong Singapore VLSFO premium: it’s a challenge 

For those of us in the bunker market, the point we made last month about Singapore VLSFO trading at a strong premium to crude still holds, albeit slightly less pronounced. The loss of supplies through the Strait of Hormuz, together with the added uncertainty surrounding Saudi product exports from the Jizan and Rabigh refineries on the Red Sea, has sustained this premium. 

These developments are likely to keep the Singapore VLSFO premium to crude at elevated levels until there is greater confidence that Middle East crude and product supplies are returning to more normal trading patterns. Amid all the price volatility, this Singapore VLSFO premium remains a key indicator to watch. 

Backwardation in Brent futures illustrates market psychology 

One month ago, backwardation in Brent futures (front month minus second month) had fallen from $7/bbl to virtually nothing, reflecting the market’s belief that an end to the war was little more than a negotiating step away. It wasn’t. The resumption of attacks, coupled with Houthi involvement in the Red Sea, sent prices sharply higher again, with backwardation in the Brent futures market returning to almost $6/bbl. 

Jul 2026 Graph 02 1024x572 1

The halt in attacks over the past weekend has taken steam out of the market, with prices and backwardation falling sharply. Where we go from here depends if there is again a belief peace is on the horizon, or if this is another false dawn. The past month highlights how impossible it is to predict an ending to the war, and how fragile any expectations of peace can be. 

We cannot ignore the price, but still must look to the future

It is impossible to write a report and not highlight the turmoil of the current market and what is happening. However, we still must look beyond this, to see where we could end up. 

In an earlier report, we suggested the run-up to the US mid-term elections in November may be a backstop to the war. However, even this is not guaranteed. There are many dynamic elements to the economy and voter intentions, but one feature that will always crop up in the US is the gasoline price. This has risen from $3/gallon before the war to over $4/gallon for the past four months. 

Jul 2026 Graph 03 1024x570 1

If it comes to it, will Republican voters want to see a resolution to the war and a return to $3 gasoline prices ahead of the elections? 

We have a change of heart on how low bunker prices can go

We don’t know exact timings, but in any planning, we must look at what happens when the war does finally end and prices fall, whenever that may be. In past reports we have highlighted the view that Brent crude prices are unlikely to fall back to pre-war levels in the $60s, and Singapore VLSFO unlikely to go back in to the $400s. This may be the point at which these views change.

Previous thinking was based on a relatively short war, where there would be a large loss of oil supply and a massive stock-draw. In this case, tighter stock levels would be sufficient to keep prices higher than their pre-war levels once we returned to ‘normality’. This would mean Brent futures in the $70s (and not in the $60s), and Singapore VLSFO in the $500s, and not the $400s.

A number of mainstream analysts also held this view, although there were some that were lower and some higher.

Given the war has already gone on for much longer than almost everyone expected, this thinking must change. Yes, global stocks have been drawn down at a rapid rate, but this is slowing. Higher pricing and inflationary blows have had a major impact on global oil demand, with current indications that total oil demand in the second quarter of this year was some 4 million b/d lower than year earlier levels.

The graph below shows this sharp drop in demand and even if the war comes to an end relatively soon, and demand gets back towards some normality, a structural loss of more than 1 million b/d in global oil demand is still expected to have taken place because of the extended period of conflict.

If the war goes on for even longer, structural losses in global oil demand are likely to be even greater.

Jul 2026 Graph 04 1024x579 1

Source: US EIA

It’s a hard road, but we can get there

This means that once the war does end, market psychology will be looking at a rapid increase in oil supplies going into a global market which is much lower in demand.  This opens the way for prices to easily return to their pre-war levels of Brent in the $60s and Singapore VLSFO in the $400s. 

Now we just need those at the centre of negotiations to get us there.

 

Photo credit and source: Integr8 Fuels
Published: 30 July, 2026

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Bunker Fuel Quality

FOBAS report warns of growing operational risks from ISO-compliant bunker fuels

LR’s latest FOBAS Fuel Quality Report reveals that the biggest fuel quality risks are no longer confined to off-specification fuels, with some compliant fuels creating operational challenges.

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New FOBAS report warns growing operational risks from ISO-compliant bunker fuels

Classification society Lloyd’s Register (LR) on Tuesday (14 July) warned that ship operators are facing a growing risk from fuels that appear compliant under routine ISO 8217 testing but still present operational risks once onboard.

According to LR’s latest Fuel Oil Bunker Analysis and Advisory Service (FOBAS) Fuel Quality Report, covering the first half of 2026, off-specification fuels remain a persistent challenge. 

However, some of the most disruptive cases now involve fuels that pass routine compliance testing but show poor stability or compatibility, or contain non-conventional blend components that are only identified through more detailed investigative analysis.

Several incidents investigated highlighted this trend. In March and April, a number of vessels reported operational difficulties after bunkering fuel in a major bunkering hub. Further forensic analysis found that many of the fuels contained elevated concentrations of Estonian shale oil, in some cases estimated to be around 10-15%.

While shale oil is recognised within ISO 8217 as an acceptable blend component, FOBAS investigations found that higher concentrations can be associated with fuel instability and operational issues affecting filters, separators and fuel pumps.

The report also shows that fuel quality variability remains stubbornly high. Off-specification cases remained elevated throughout the first six months of 2026, suggesting that quality issues are no longer isolated events but a more persistent feature of today’s marine fuel supply chain.

The most common recurring issues included sulphur exceedances, excessive water content, sediment and stability problems, elevated catalytic fines, sodium contamination and low flash point distillate fuels.

At the same time, biofuels (especially FAME blends) are continuing to grow without being a primary source of quality issues. Where issues occurred in blended fuels, they were generally associated with the conventional VLSFO component rather than the FAME fraction.

The report concluded that operators will need to adopt a more proactive approach to fuel management as marine fuels become more diverse and fuel quality risks become harder to identify through routine compliance testing alone.

Greater emphasis on fuel stability, compatibility and understanding fuel composition will be critical to reducing operational disruption and maintaining vessel performance.

Murray Kirkwood, Fuel Specialist Consultant, Lloyd’s Register, said: “The findings from our latest report show that fuel quality risk is evolving. The challenge is no longer simply identifying fuels that fail specification. Increasingly, operators are encountering fuels that meet the required limits but still create operational difficulties once they are stored, handled and used onboard.

“As fuel blending becomes more complex, the distinction that matters is increasingly not between on-spec and off-spec fuel, but between fuels that are operationally resilient and fuels that are operationally fragile. Understanding that difference is becoming essential for shipowners and operators.”

The latest findings reinforced FOBAS’ long-standing view that effective fuel management increasingly depends on understanding fuel behaviour rather than relying solely on pass-or-fail specification testing.

By combining routine fuel quality monitoring with forensic investigation of operational incidents, FOBAS provides shipowners with a clearer understanding of emerging fuel quality risks as the industry continues its transition to a more diverse and complex fuel landscape.

Note: The FOBAS Fuel Insight: Fuel Quality Report H1 2026 is available at FOBAS Fuel Insight: Fuel quality reports | LR

 

Photo credit: Lloyd’s Register
Published: 15 July, 2026

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