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Bunker Fuel Quality

Gard offers recommendations to mitigate risk of catfines in marine fuel

Following reports by members and clients indicating a significant increase in catfines in both VLSFO and HSFO in major bunkering ports during August 2025, the P&I club outlines its recommendations.

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Following reports by Gard members and clients indicating a significant increase in catfines in both Very Low Sulphur Fuel Oil and High Sulphur Fuel Oil in major bunkering ports during August 2025, maritime protection and indemnity (P&I) club Gard offered key recommendations in this article, published on 9 September, to mitigate risk of catfines in marine fuel:

We refer to Veritas Petroleum Services’ (VPS) Circular ‘A Global Pandemic of High Catfines in Marine Fuel’ dated 4 September 2025. Between 11 August and 31 August 2025, VPS observed a high number of elevated catfine levels, ranging from 62-176 ppm, in fuel across the regions shown in the below illustration. This is a trend that mirrors Gard’s own experience.

Gard offers recommendations to mitigate risk of catfines in marine fuel

Understanding catfines

Catfines are microscopic, abrasive particles that pose a significant threat to a vessel’s engine. Short for catalytic fines, these particles are composed mainly of aluminum (Al) and silicon (Si). Along with viscosity and water, catfines are considered one of the three most critical properties to monitor in fuel quality at the engine inlet. To put their size into perspective, catfine particles range from 1 to 75 microns. A micron, or micrometer, is just 0.001 millimeters. In comparison, a human hair is about 50 to 70 microns thick, and a fine grain of sand is around 90 microns. Larger particles are more abrasive and can cause severe wear and damage to critical engine components such as cylinder liners, piston rings, and fuel injectors.

Catfines are extremely hard and abrasive. They can scratch or become embedded in the steel surfaces of marine engine components, particularly those that move against each other. When they enter an engine, they can lead to high wear rates and scuffing, resulting in costly damage to key parts. Factors like a vessel’s motion in rough seas can stir up previously settled material in fuel tanks.

Catfines in VLSFO

The problem with cat fines is compounded in VLSFO due to several factors. The fuel’s typically low viscosity can reduce the effectiveness of centrifugal separators, while its varied composition makes its behaviour unpredictable. If the fuel is not sufficiently heated, waxes can precipitate and clog purifiers and filters, further diminishing their ability to remove these abrasive particles. Adding to the complexity is the risk of re-dissolving cat fines from old tank sediments. Given these challenges, rigorous fuel management is critical.

Industry standards

The ISO 8217 standard sets a maximum limit for catfine levels in fuel. The 2010, 2012, 2017, and 2024 versions set a maximum limit of 60 mg/kg (or 60 ppm) for viscous fuel grades as delivered to the ship. This limit is a significant reduction from the 80 mg/kg limit listed in the 2005 standard. It is crucial to note that the ISO 8217 limit applies to the fuel as it is delivered, not as it enters the engine. 

For safe operation, most engine manufacturers recommend that catfine levels at the engine inlet be much lower — ideally below 15 ppm. To meet these requirements, vessels must rely on effective onboard fuel treatment systems. An overview of some of the major OEM requirements for fuel quality before the engine and for fuel cleaning systems can be found in Appendix I of CIMAC Guideline Design and operation of fuel cleaning systems for diesel engines (09, 2024 v2).

Key recommendations

Effective management of cat fines is crucial to prevent engine damage. While most owners and managers have established procedures, we reiterate some of the most important practices to mitigate the risk. 

Bunkering & Sampling

  • Source fuel carefully – Prioritize reputable suppliers when bunkering and avoid less-known local providers.
  • Define clear specifications – Ensure charter parties include detailed fuel specifications, latest ISO 8217 standard, recommended suppliers, and precise handling and sampling requirements.
  • Follow standard procedures – Adhere to industry-standard sampling practices, including taking samples from the ship’s manifold, using proper cubitainers, and ensuring all documentation (such as the Bunker Delivery Note) is correctly completed.
  • Analyze before use – Conduct a thorough sample analysis before using the new fuel.

Onboard Storage & Settling

  • Increase segregation – Maintain increased bunker segregation to avoid contamination.
  • Test for compatibility – If mixing is unavoidable, conduct compatibility testing and follow specified mixing ratios.
  • Allow for settling – Ensure the fuel has appropriate settling time in the tanks.
  • Drain tanks – Settling and service tanks should be drained a minimum of twice daily.
  • Clean tanks – Clean settling and service tanks whenever possible to remove sediment.

Purification

  • Choose the right purifier disc based on the fuel’s density.
  • Operate at the correct temperature as recommended by the fuel analysis report.
  • Consider using both purifiers (in parallel or in series) at appropriate feed rates to increase efficiency.
  • Maintain purification units with proper care and maintenance.

Monitoring & Prevention

  • Monitor fuel filters carefully for signs of clogging.
  • Be aware of sludge formation and filter clogging, particularly after heavy weather.
  • Conduct regular sample analysis of fuel from before and after the purifier to confirm the unit’s efficiency.
  • Perform periodic cylinder scrape-down analysis to check for abrasive wear.
  • VPS also recommends taking fuel system check samples to assess the fuel treatment efficiency at the engine inlet or as close to it. This data is critical for any subsequent assessment of increased engine wear.

We would like to thank Veritas Petroleum Services for the above information.

 

Photo credit: Shaah Shahidh on Unsplash and VPS
Published: 23 September, 2025

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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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Bunker Fuel Quality

VPS on lifeboat fuel quality: A safety of life at sea critical risk

Neil Chapman and Steve Bee said regular fuel testing, correct fuel selection, and proactive fuel management are essential to ensure lifeboats are ready when they’re needed most.

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Neil Chapman, Managing Director of Americas, and Steve Bee, Group Marketing and Strategic Projects Director of marine fuels testing company VPS, on Monday (13 July) said regular fuel testing, correct fuel selection, and proactive fuel management are essential to ensure lifeboats are ready when they’re needed most: 

Performance when its most critical

In an emergency, a lifeboat engine is not simply a mechanical asset, it is a life-saving system. If the fuel in that system is of poor quality due to degradation, contamination, or simply unsuitable for the operating environment, then the result may be failure to launch, manoeuvre, or sustain operation, when human lives depend on it. Fuel failures in lifeboats onboard Cruise Liners are high-consequence life-safety risk as the engine may be the only power source available during an emergency. It is a key SOLAS (Safety of Life at Sea) requirement that lifeboats should hold sufficient fuel to enable them to run at 6 knots for no less than 25 hours.

The primary consequence of a lifeboat failure is not the commercial  loss, but the potential failure of a safety-critical system during an abandon-ship scenario. Financial, legal and reputational consequences will undoubtedly follow but the immediate risk is to life.

Now with the inclusion of Biofuels and FAME in the marine fuel mix and assuming the same fuel used in the main engines may be used in the emergency systems, how do you verify the operability of the lifeboats in times of crisis?

Fuel grade DMX within the ISO8217 specification is specifically intended for use within emergency equipment. However, since this is not a mandatory requirement, marine gas oil (MGO grade DMA) used for other purposes on board, is often used to fill up lifeboat fuel tanks. This could lead to hazardous outcomes as the DMA grade fuel might not be suitable for its intended use. DMA fuel whilst acceptable for general machinery use, will unlikely provide the same assurance of low-temperature operability, ignition quality, storage reliability, or starting reliability required for emergency craft. The quality of the fuel in the lifeboat tanks may also deteriorate during storage. Hence it is essential to test and ensure that the quality of the fuel being taken into the tanks is ’fit for purpose’ and monitored at regular intervals. DMX fuel should be chosen due to its ability to operate at a lower temperature, superior ignition quality and  improved starting capabilities. However, this fuel only accounts for approximately 1-2% of the global supply, compared to the regular DMA grade.

Failure Modes in Emergency Operations

SOLAS compliance should not be viewed only in terms of carrying the required quality of fuel. The fuel must also remain fit-for-purpose regarding stability, cleanliness and be capable of supporting reliable engine operation throughout the vessel’s operation. Lifeboat failures are rarely a singular dramatic event, rather a chain of events. These are typically caused by degraded fuel, filter blockages or storage issues.  Incorrect handling and storage can result in the ingress of water, which with modern fuels, can promote the growth of filter blocking bacteria rendering the engine inoperable.  So rather than the issue being no fuel, it is more likely to be an issue of fuel that is of poor quality. As lifeboat engines may sit idle for long periods it potentially allows the fuel to degrade, if the correct due care and attention is not paid to this key piece of emergency equipment.

The handling and storage of fuel, coupled with the observance of quality operating procedures can lessen the risk of these failures, but are unlikely to eliminate them completely. However, the failure to follow established procedures can result in issues that are likely to cause catastrophic financial and reputational damage to the cruise line operator.

The most common failure modes in emergency lifeboats can be categorised as follows:

  • Fuel Starvation
  • Contamination
  • Degraded Fuel
  • Blocked Filter/Injectors

Contamination in the engine due to the presence of water, as previously mentioned, can be catastrophic as this can induce corrosion and oxidation, along with promoting microbial growth which results in filter blocking and fuel starvation to the engine.

If an engine fails to start, or runs poorly under load, due to fuel related issues this would likely cause a secondary emergency, compounding the reason the lifeboat was required in the first instance.

The danger with degraded fuel is that the risk is often hidden. A lifeboat may appear available, inspected and compliant, whilst he fuel inside its tank is steadily losing the properties required for reliable emergency operation.

IMO guidelines indicate that inspectors and regulators are increasingly looking at emergency systems for fuel compliance, highlighting its importance in the operation of a vessel.

Seasonal & Regional Fuel Requirements

Often overlooked are the cold flow properties of diesel and biofuels.  While hydrocarbon-based diesel has very good (low temperature) cold flow properties, this is not the case for biofuels, so lifeboats fuelled in the Caribbean for the summer season may be completely inoperable if the vessels are transferred to the Northeast or higher location, for a winter period.

Root Cause Failure Mechanisms

The failure to follow the appropriate standards which result in engine failure can be categorised as follows:

image 45

The Effect of Biofuels on Marine Fuel Quality

In a study recently completed by a major shipping line, blends of biofuels were tested for a wide range of parameters.  The findings were:

Biological growth appeared within the first month, increasing rapidly with exposure to light.

Within 3 months oxidative corrosion started to occur requiring regular monitoring.

46 CFR § 169.837 states:

“(2) The fuel tanks of motor propelled lifeboats have been emptied, and fuel changed once every twelve months.”

Yet the evidence shows fuel stability effectively starts to deteriorate within the first month and can be unusable by month 3.

Prevention Strategy

Fuel testing should be viewed as part of the vessel’s safety assurance programme. It provides evidence that the lifeboat fuel remains fit-for-purpose, not only on the day it was supplied, but throughout storage and across changing operational conditions. A strong housekeeping policy requires a multi-pronged approach to ensure operability in times of crisis; such steps include:

  • Housekeeping – ensuring the fuel system remains closed when not in use to eliminate the ingress of water.
  • Operation – frequently run the engines so that fuel and lubricants are cycled through the units.
  • Testing program – likely to be cheaper and more efficient than changing out the fuel. A well-developed fuel testing program can eliminate the need to change the fuel.
  • Documentation – by recording all the actions taken to protect the emergency systems historic data can be tracked.

Advanced Testing Programs

Due to the importance of these emergency assets several different tests should be considered to ensure the suitability of the fuel.  Testing should include:

  • Cold-Flow properties using Pour Point, Cold Filter plugging Point, Cloud Point
  • Water content for moisture
  • BYF for Microbial testing
  • Acid Number for corrosion tendencies
  • FAME for biofuels content
  • Sulphur for MARPOL Annex VI compliance
  • Visual Appearance
  • Viscosity for flow properties
  • Density
  • Flash Point for SOLAS compliance
  • Cetane Index

Conclusion

It is possible to avoid engine failures, but this can only be achieved with a well-documented and well-followed operating procedure.  Regular fuel sampling and testing along with general good housekeeping techniques will ensure these units are ready go when they are most needed. Once they are seen as an active safety-critical asset rather than a dormant emergency component the value in this process will be realized.

Lifeboat fuel quality is not a housekeeping detail, it is a Safety of Life at Sea issue. Emergency craft must be capable of starting manoeuvring and operating for the required duration whenever called upon. Sub-standard, degraded, contaminated, or unsuitable fuel can compromise that capability and turn an emergency response into a secondary emergency. Regular testing, correct fuel choice, controlled storage and documented fuel management provide the evidence and assurance that lifeboats remain ready when lives depend on them.

 

Photo credit: VPS
Published: 14 July, 2026

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Engine

VPS on precision testing for reliable engine performance: Importance of coolant analysis

Steve Bee of VPS highlighted that coolant analysis can prevent failures through early chemical detection, protect components, maintain performance, plus reduce costs and downtime.

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Steve Bee, Group Marketing and Strategic Projects Director of marine fuels testing company VPS, on Thursday (9 July) highlighted that coolant analysis can prevent failures through early chemical detection, protect components, maintain performance, plus reduce costs and downtime: 

Engine coolants play a critical role in protecting equipment performance, efficiency, and longevity. As cooling system technologies and coolant formulations continue to evolve, regular laboratory analysis has become an essential part of proactive maintenance.

It is widely known that coolants should be managed with the same discipline as other critical fluids, as chemical changes can develop long before visible failures occur.

However, it must be emphasized that coolant analysis is about reliability, not just fluid condition. Modern engines and cooling systems operate under higher thermal loads and tighter tolerances, so even small changes in coolant chemistry can affect corrosion control, heat transfer, and component life.

An effective coolant analysis service should provide operators with an early warning system, helping to identify contamination, degradation, and inhibitor depletion before they become operational failures. The service can be a practical tool for reducing downtime, preventing avoidable repairs, and extending equipment life.

As stated above, many cooling system issues start at the chemical level, long before anything is visible and without analysis you are effectively blind until a failure starts. Through coolant testing, risks such as corrosion, cavitation and scale formation can be detected long before damage occurs.

image 41

As an example, the above images show the damage that can occur when a coolant does not have sufficient concentration to provide adequate protection. This damage can appear as scale formation, reduced heat-transfer efficiency and lower flow rates, which can ultimately lead to corrosion.

Coolants don’t just control temperature, they also chemically protect engines and coolant systems. They effectively prevent corrosion of metals and components, reduce cavitation damage in liners and pumps and help avoid deposit build-up and blockages in heat exchangers. Its true that cooling system damage, is a major source of engine failure.

Coolants must be chemically stable in order to transfer heat effectively, as poor cooling performance directly impacts engine efficiency, fuel consumption and reliability. As a predictive maintenance tool coolant analysis moves operations from emergency repairs to planned maintenance.

Should coolants exhibit degrees of incompatibility, then further issues can arise. Mixing incompatible coolants can cause sludge formation, which will in turn affect coolant circulation, leading to reduced efficiency. In addition incompatible coolants can form sludge or gels, which negatively impacts circulation and heat transfer creating hotspots. Those hotspots can break down lubrication and cause micro-welding between piston and liner surfaces, leading to piston pick-up.

image 42

Historically, many coolants were relatively simple glycol/water formulations supported by inorganic inhibitors such as silicates, phosphates, or borates. However, modern coolants are more sophisticated, including OAT, HOAT, NOAT, POAT, and other specialized blends designed for longer service life and improved protection. This added sophistication creates a need for verification: when systems are topped up, mixed, contaminated, or serviced.

Organic Acid Technology (OAT) coolants, can be formulated with various organic acids such as Sebacate, which is an ester of sebacic acid. Sebacate exhibits low volatility and excellent flexibility at low temperatures. Also tolytriazole can be a component, which is best known as a thermally stable, metal corrosion inhibitor.

So organic acid technology uses organic acids to provide targeted corrosion protection, especially for aluminum and mixed-metal systems. The advantages are, long service life of up to seven years, reduced abrasive deposits, and protection that is generally gentler on seals and components. However, whilst such coolants offer long service life, OAT coolants are not maintenance-free. Its also possible that coolant protection can be slow to establish and performance can be compromised by incorrect mixing, contamination, or loss of inhibitor balance. This is where routine analysis helps verify that the coolant is still doing its job.

Hybrid Organic Acid Technology (HOAT) coolants are newer generation coolants which combine organic acid technology with selected inorganic additives. They aim to provide both long-life protection and faster initial corrosion control through improved heat transfer and cooling performance. This makes them attractive for demanding engines and systems where heat transfer, compatibility, and corrosion control are all critical. The important point is that HOAT chemistry is more complex than traditional coolant chemistry. That complexity can make correct identification, compatibility, and contamination control more difficult. The downsides to HOAT coolants are they are more expensive than traditional coolants, but more concerning is they can be more susceptible to becoming contaminated, affecting their effectiveness and lifespan. Therefore, routine lab testing helps confirm whether the coolant in service still matches the intended formulation and whether the inhibitor package remains effective.

The shipping fleet has numerous sectors and each have various considerations when it comes to the use of coolants:

image 43However, the underlying need for each shipping sector is similar, in that cooling-system reliability supports uptime, safety, and cost control. Deep-sea shipping, offshore and marine services, harbour and coastal operations, cruise and ferry operators, inland waterway vessels, plus port or terminal operators, all have equipment where coolant condition can affect reliability. The commercial message is that coolant analysis can be positioned alongside existing marine fluid management services, making it a logical extension rather than a separate standalone offering.

A typical coolant analysis test slate includes the following tests highlighting what each test parameter detects, their frequency and benefits:

image 43

To take an analogy from Oil Condition Monitoring, Coolant Analysis is effectively a “blood test” for the cooling system.

So in summary, Coolant Analysis can prevent failures through early chemical detection, protect components, maintain performance, plus reduce costs and downtime.

 

Photo credit: VPS
Published: 10 July, 2026

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