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Bunker Fuel Quality

VPS: How elevated catfines can damage marine engines

VPS’ latest article highlights the dangers catfines can cause within vessel engines and how to avoid damages by using its fuel system check service.

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Marine fuels testing company VPS on Wednesday (6 May) released an article highlighting the dangers catfines can cause within vessel engines and how to avoid damages by using the VPS fuel system check service: 

A common concern of maritime chief engineers, regarding vessel engine damages, is the presence of highly abrasive “catfines” within marine fuel. To fully understand the seriousness of this issue, we first need to understand the source of the problem.

Oil refineries use catalysts in their Fluid Catalytic Cracking Units (FCCU) or “Cat Plants” to process crude oils in the production of numerous products from the source crude. These catalysts are high in aluminium silicate (Al+Si) content and over time and repeated use, can breakdown and fragment into smaller particles, or catalytic fines. These catalytic fines, known throughout the industry as “Catfines” can eventually find their way into the heavier refining streams and consequently the HSFO and VLSFO fuels being burnt onboard vessels. Higher levels of catfines within the fuel can be extremely abrasive and damaging to ships engines.

It is critical to note the ISO8217 specification limit for Al+Si for residual fuels delivered to the ship, is 60 mg/Kg for all revisions post-2005. This level is significantly greater than the OEM engine inlet limit of 15mg/Kg and therefore the fuel requires efficient onboard purification, monitored via a frequent fuel-system-check, process in order to avoid potentially catastrophic engine damages.

From a recent review of more than 3,000 Fuel System Check samples taken before-purifier and after-purifier, VPS found 16% of the fuels after-purifier catfine concentrations were above the 15mg/Kg OEM limit. This indicates that some 480 vessels had purifiers failing to operate to their optimum efficiency in order to protect the engine.

At this time of the Middle East military conflict, one might suspect that refinery output around the wider region to have been impacted by crude availability, thus reducing the ultimate throughput of any refinery. However, under certain refinery operating conditions, reduced throughput may lead to higher relative concentrations of catfines in heavier streams. Thus these catfines can potentially end up in marine fuel supply chains.

In 2-stroke crosshead engines, ineffective removal of catfines can result in their entry into the combustion chamber, where they cause abrasive wear between piston rings and cylinder liners. Conversely, medium speed engines tend to be generally more tolerant, due to continuous oil circulation and filtration, but still vulnerable if catfine levels are excessive.

Another consideration within this equation is that cylinder oil (used exclusively in 2 stroke engines) is “single use” and exhausted after first use. Thus it’s overuse, in any attempt to combat catfines and minimise wear can be commercially punitive, unnecessary and in some cases contribute to damages, exacerbating the “grinding paste” effect occurring within the cylinder liners.

Cylinder lubricants are primarily a base oil, plus an additive “pack” (a combination of carefully selected compounds focused on providing various qualities e.g. Base Number (BN) to combat fuel sulphur and detergency to clean etc). However, inappropriate cylinder oil selection, or excessive feed rates may contribute to deposit formation on piston crowns and ring zones. 

Over-lubrication is not an effective mitigation strategy as it may increase deposit formation and will certainly increase operating costs.

A first step to prevention of catfine damage would be in the selection of a reputable supplier, known for delivering low-catfine fuel. Data in relation to this is highlighted in the VPS PortStats application. However, its recognized on numerous occasions, the owner/operator of the ship dealing with sub-standard fuel is not the entity who purchased the fuel. Therefore, further practical considerations should also be made including, appropriate tank cleaning, circulation and movement to avoid catfine settling and concentration at much higher levels than the original test results obtained from the vessel manifold sample.

In the case of managing catfine levels above OEM engine entry limits, effective purification remains key. Statistically, a vessel will suffer one to two instances of main engine damage over the course of her operational lifetime. These costs can reach millions of dollars, far more than the average main engine damage costs of $650K highlighted in the Swedish Club paper “Engine Damage”. https://www.swedishclub.com/uploads/2023/12/TSC-Engine-Damage-WEB2023.pdf 

Monitoring and Quality Control – Fuel System Checks (FSC)

It is essential that fuel samples are taken both before and after purifier. This should be carried out at regular intervals (on a quarterly basis), with increased frequency when high catfine levels are identified. In addition, whenever VPS see a vessel manifold sample with a catfine level >40kg/Kg, an alert is automatically sent to the vessel, with the instruction to take additional before and after purifier samples, as a cautionary procedure.

There are numerous reasons why regular fuel system checks are critical:

  •   Help identify potential risks & operational issues before major damage occurs.
  •   Confirm that the system’s flow rate, temperatures, discharge cycles are properly adjusted to handle the specific fuel that is being treated
  •   Verify that the fuel treatment system is properly maintained
  •   Reduce operating cost and increase lifecycles of critical components
  •   Identify presence of unusual components that can enter fuel post- delivery.

Periodic sampling from the fuel treatment system will also identify problems such as water ingress from ballast systems, leaking heating coils and cargo contamination. 

Core Operating Conditions

In addition to the FSC programme it is key to undertake the following practices:

Maintain the correct inlet temperatures as purifiers rely on centrifugal separation, enhanced by density differences. The fuel must be heated to the manufacturer-specified temperature for optimal separation and reduced carry-over.

Ensure the separator is correctly configured and operated (e.g. gravity disc selection in conventional units or proper control settings in automated systems) to avoid reduced separation efficiency, which could allow water or catfines to pass through to the engine.

Keep the feed-rate of fuel slow and steady. Running purifiers in parallel at minimum feed-rate improves separation and reduces carryover.

Match settings to oil density. Density changes with fuel grade, so adjusting settings ensures proper bowl separation.

Maintenance Practices that Directly Improve Efficiency

Clean filters and heaters regularly. Blocked filters or fouled heaters reduce flow and temperature stability, lowering purification quality.

Clean fuel tanks at scheduled intervals. This prevents high sediment and catfine concentrations from overwhelming the purifier.

Avoid by-passing any fuel-treatment equipment. By-passing risks engine damage and eliminates the purifier’s protective function.

Ensure adequate spare parts are onboard. Worn seals, gaskets, or disc stacks, reduce bowl pressure and separation efficiency.

Follow the vessel’s preventative maintenance schedule and manufacturer’s intervals. Planned maintenance ensures consistent cleaning, inspection and overhaul cycles.

Summary

So, with the recent survey by VPS finding 16% of fuels after-purifier catfine concentrations were above 15ppm, this highlights the fact, these purifiers are failing to operate to their optimum efficiency and their primary function to protect the engine.

All the above, monitoring, quality control and operational steps, are key to ensure a vessel’s engine is protected from the abrasive wear catfines can cause. Plus, by following this advice, the vessel will see an improvement in combustion efficiency due to burning cleaner fuel. This will all result in reduced downtime and repair costs, avoiding purifier failures which can lead to major engine issues.

 

Photo credit: VPS
Published: 7 May, 2026

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Bunker Fuel Quality

IBIA: Shale oil presence alone do not indicate bunker fuel non-compliance

IBIA says available evidence does not establish a direct causal relationship between the presence of shale oil and the operational issues reported.

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July 28, 2026

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The International Bunker Industry Association (IBIA) on Monday (27 July) said it is aware of recent reports highlighting operational issues observed in connection with certain residual marine fuels containing components which may indicate the presence of shale oil. 

IBIA said its Technical Working Group has reviewed the information currently available and noted that, while these reports raise legitimate questions that warrant further investigation, the available evidence does not establish a direct causal relationship between the presence of these compounds and the operational issues reported. 

“Shale oil-derived hydrocarbons are a permitted feedstock under ISO 8217. Their presence alone should not be regarded as evidence of fuel quality deficiencies or non-compliance,” IBIA said in a statement. 

“The relevant consideration is whether the finished fuel, as delivered, meets the requirements of ISO 8217, including the provisions relating to fuel composition and operational fitness for use. 

“The reported cases nevertheless reinforce the importance of understanding how increasingly complex marine fuel blends perform in practice.”

Manifold Times previously reported Lloyd’s Register Fuel Oil Bunkering Analysis (FOBAS) stating that tests on several fuels from Singapore identified a chemical fingerprint consistent with Estonian shale oil, while vessels using these fuels reported operational issues. 

Marine fuels testing company VPS reported it has seen an increase in the levels of shale oil components in marine fuels bunkered recently in Singapore

As the industry continues to diversify feedstocks and blend components, greater transparency, traceability, IBIA said quality assurance and information sharing across the supply chain will become increasingly important. 

“IBIA supports further technical investigation, industry collaboration and data sharing to improve understanding of fuel behavior and operational performance. Such work will help ensure confidence in marine fuel quality while supporting the safe, reliable and efficient operation of ships,” it added. 

Related: FOBAS: Estonian shale oil and stability issues found in marine fuels from Singapore
Related: VPS: Shale oil components detected in marine fuels in Singapore

 

Photo credit: International Bunker Industry Association
Published: 28 July, 2026

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Bunker Fuel

Bureau Veritas: VeriFuel publishes overview of Q2 2026 global bunker fuel quality

Elevated Al+Si levels in VLSFO 0.50% continue to be observed in ports such as Port Klang and Singapore, while sediment-related concerns were identified in several European locations.

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Bureau Veritas: VeriFuel Fuel Quality Testing Annual Report 2024

French testing, inspection and certification firm Bureau Veritas recently provided Singapore bunkering publication Manifold Times a copy of its VeriFuel Fuel Quality Testing Q2 2026 Report which provides an overview of marine fuel quality, emerging trends, and compliance levels based on all tested bunker samples across its laboratories. The following is an overview of the report:

VLSFO

Global Quarterly Averages

Global VLSFO quality indicators in Q2 2026 remain stable. Viscosity, density and cat fines have slightly increased compared to Q1 2026. The overall off-spec rate increased slightly to 1.5%, although still remaining within historical norms.

Global Monthly Averages

Monthly data for Q2 2026 show relatively limited variability across all key parameters. Viscosity increased progressively from April to June, while sulphur and sediment levels remained stable. Off-spec incidence declined throughout the quarter, suggesting an improvement in regards to ISO.

Global Quarterly Pour Point Distribution

The pour point distribution in Q2 2026 remains largely consistent with previous quarters. Majority of samples continue to fall within low temperature ranges (≤ 21 °C) while cases at or slightly above limit are very limited.

Global Quarterly Out-of-Spec Parameters

Sulphur, water, sediments and cat fines continue to represent the primary causes of VLSFO non-compliance in Q2 2026 while the ratio of all properties have increased compacted to Q1 2026.

VLSFO 0.50% Port Averages

Regional variations remain evident across fuel properties. Elevated Al+Si levels continue to be observed in ports such as Port Klang and Singapore, while sediment-related concerns were identified in several European locations. Sulphur remains the most commonly reported cause of non-compliance across major bunkering hubs.

Screenshot 2026 07 28 at 1.27.27 PM

Screenshot 2026 07 28 at 1.27.41 PM

Sediments by Quarter

The percentage of fuels exceeding the sediment threshold (≥0.07% m/m) increased compared to Q1 2026. While most fuels remain within ISO 8217 limits, the rising trend highlights the continued importance of good housekeeping and management on board vessels. Most notable increase is observed in Gothenburg and Skagen.

Cat Fines (Al+Si) by Quarter

The proportion of VLSFO samples containing elevated cat fines increased slightly during Q2 2026. Although most fuels remain compliant with ISO 8217 limits, proper treatment on board remain a critical aspect in order to meet engine manufacturer recommendation of max 10 mg/kg at engine inlet.

Acid Number by Quarter

Acid number levels in Q2 2026 remain generally stable and well below the 1.2 mg KOH/g threshold for the majority of samples. However, isolated ports continue to report elevated average acid numbers, particularly in Singapore and Zhoushan, warranting ongoing monitoring of blend composition and feedstock sources.

HSFO 

Global Quarterly Averages

HSFO quality indicators in Q2 2026 remained generally stable. Sulphur content continued its downward trend and density declined slightly, while cat fines increased. The overall off-spec rate increased significantly to 2.4%, representing the highest level observed since early 2024 and indicating a deterioration in overall conformity.

Screenshot 2026 07 28 at 2.14.21 PM

Global Monthly Averages

Monthly trends during Q2 2026 show limited parameter variability, with sulphur decreasing steadily from April through June. Off-spec frequency increased sharply after April and remained elevated during May and June, suggesting persistent quality challenges during the quarter.

Screenshot 2026 07 28 at 2.14.10 PM

Global Quarterly Out-of-Spec Parameters

Water, density, sediments and viscosity remain the leading contributors to HSFO non-compliance in Q2 2026. Compared with previous quarters, water is noted as the leader cause of ISO8217 non-compliance followed by sediments.

HSFO 0.50% Port Averages

Significant regional variability continues to be observed in fuel properties. Several ports such as New Orleans, Houston, Balboa and Algeciras reported average Al+Si levels approaching or exceeding 36 mg/kg. Water and sediment lead as the most frequent non-compliant properties across most locations.

Sediments by Quarter

The proportion of HSFO samples exceeding the sediment threshold (≥0.07% m/m) increased further during Q2 2026 compared with both Q1 2026 and the corresponding quarters of 2025. The rising trend highlights the continued importance of good housekeeping and management on board vessels.

Cat Fines (Al+Si) by Quarter

The proportion of HSFO samples containing elevated cat fines increased slightly during Q2 2026. Although most fuels remain compliant with ISO 8217 limits, proper treatment on board remain a critical aspect in order to meet engine manufacturer recommendation of max 10 mg/kg at engine inlet. Most notable increase was observed in Damietta, Houston and New Orleans ports.

Acid Number by Quarter

Acid number above 1.2 mg KOH/g remain concentrated in a limited number of regions. ARA, Singapore and Zhoushan are the most notable for which some extra attention is required especially related to the fuel composition and nature of acids origin in the fuel.

Screenshot 2026 07 28 at 2.12.03 PM

DMA

Global Quarterly Averages

Global DMA quality indicators in Q2 2026 remained stable. Viscosity increased slightly compared with Q1 2026, while sulphur content declined and cetane index remained unchanged. The overall off-spec rate slightly improved to 2.4 compared to previous quarters.

Global Monthly Averages

Monthly averages for Q2 2026 demonstrate limited variation across fuel properties. Off-spec frequency remained relatively moderate with no clear upward or downward trend throughout the quarter.

Global Quarterly Out-of-Spec Parameters

Appearance usually combined with water as well as pour point and sulphur remain the principal contributors to DMA non-compliance in Q2 2026. Based on individual values the Pour Point and Sulphur are considered of higher importance compared to water content.

DMA 0.10% Port Averages

Substantial regional differences remain evident across regions. Water continues to be the most frequently reported cause of non-compliance across several major bunkering locations, while isolated cases of viscosity, sulphur and pour point related non-conformities persist.

CFPP by Quarter

The proportion of DMA samples with CFPP values exceeding 6°C increased slightly during Q2 2026. This reflects seasonal and regional supply effects and emphasizes the importance of selecting fuels appropriate for the expected operating regions.

Pour Point by Quarter

Pour point exceedances above 0°C remain present in Q2 2026 and show a slight increase compared with Q1 2026. Although cases are limited, operators should continue considering ambient conditions when planning fuel procurement.

Water by Quarter

The proportion of DMA samples containing water in excess of 300 mg/kg remained a recurring concern in Q2 2026. Water-related non-compliance continues to be mainly associated with European and Mediterranean supply locations, reinforcing the importance of good storage, transfer and housekeeping practices. At least positive remain the fact that operational issues due to water presence remain limited.

 

Photo credit: Bureau Veritas
Published: 28 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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July 15, 2026

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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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