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Bunker Fuel Quality

VPS: Key steps in avoiding risk of receiving bad bunker fuels

Steve Bee, Dr Malcolm Cooper and Stanley George explain how to safeguard vessel operations against the impact of bad bunkers and share on the key steps that should be taken to avoid the risk of receiving bad bunkers.





Steve Bee, VPS Group Commercial Director, Dr Malcolm Cooper, VPS CEO and Stanley George, VPS Group Science & Technical Manager explained in an article on how to safeguard vessel operations against the impact of bad bunker fuels and shared on the key steps that should be taken to avoid the risk of receiving bad bunkers:

Bad bunkers can significantly impact vessel operations, necessitating intervention from the crew and in some cases result in operational failure - varying from operational damage through to loss of power and subsequently loss of propulsion. Mitigating the impact of bad bunkers can help to prevent damage to vessel’s equipment and protect the safety of those on board and the environment. Bad bunkers can lead to fuel stability problems, chemical contamination and poor cold-flow properties. This paper describes the key steps that should be taken to avoid the risk of receiving bad bunkers.

Bad Bunkers

Bad bunkers refer to fuel of substandard quality, which can lead to operational disruptions and challenges in fuel management. Common fuel quality concerns include poor stability, chemical contamination, corrosive tendencies, poor combustion and poor cold flow characteristics. Thorough testing of bunkered fuel prior to putting it in operation is highly advantageous as it reveals potential issues inherent in the fuel. This data often enables proactive measures to mitigate the risk of operational complications stemming from such fuel.

Whilst the general quality of bunker fuel has been consistent over recent years, it is important to note that off-specification fuel statistics are typically based on the criteria outlined in Table 1 and 2 of ISO 8217 standard. There have been numerous occasions when bunker fuel meeting these criteria has proven to be unsuitable for onboard use due to its poor quality and on a number of occasions has caused catastrophic failures (e.g. ARA contamination case - August 2022 and March 2024, Houston contamination case April 2023 and Singapore contamination case August 2022). This necessitates additional testing methodologies such as GCMS, WAT/WDT, and Reserve Stability Number to accurately assess fuel quality.

The increase in reported operational issues stemming from contaminated fuels, which often elude detection through routine ISO 8217 testing, has experienced a notable uptick in recent years. This trend can be attributed, at least in part, to the drive towards decarbonization, notably spurred by initiatives such as IMO 2020. Consequently, fuel suppliers are increasingly experimenting with a diverse range of feedstocks to serve as blend components in conventional fossil fuels.

As the world’s largest marine fuel quality testing company covering 50% of all fuel testing, VPS can offer valuable insights and advice in relation to poor quality and/or contaminated fuel. Proactive, pre-burn, fuel testing on a regular basis, is definitely a highly recommended approach to mitigating risks to vessel operations, crew safety and environmental impact. The typical off-specification parameters associated with engine failure are usually Pour Point, Total Sediment Potential, Cat-fines and/or Water content. Whilst the International Marine Fuel Quality standard, ISO8217, includes these test parameters, it’s certainly a more diligent and wiser approach, to consider a fuel’s overall stability, cold-flow properties, chemical contamination and potential corrosivity.

At VPS, we possess the proficiency and extensive experience necessary to conduct specialised tests specifically designed to detect these issues. Our tailored testing protocols enable us to identify potential fuel-related challenges and offer operational guidance to minimise associated risks effectively.

Fuel Stability

Both High Sulphur Fuel Oils (HSFOs) and Very Low Sulphur Fuel Oils (VLSFOs), can suffer with varying degrees of instability due to thermal-aging and over-heating, high sediment content, or chemical contamination, to name but a few potential causes. Instability usually manifests itself through sediment formation, which can in turn, block onboard filters, pipework, potentially then starving an engine of fuel.

ISO8217 includes the Total Sediment Potential (TSP) test, which is a good indicator of the amount of sediment which may be potentially produced in relation to a fuel’s stability. However, additional tests such as Total Sediment Accelerated (TSA), a deliberate fuel-aging test, Total Sediment Existent (TSE), a measure of fuel cleanliness and the determination of a fuel’s stability reserve, via Separability Testing, to measure the fuel’s capacity to hold long chain asphaltenes within the fuel solution, can provide much more information regarding fuel stability determinations.

In particular, Separability Number is an excellent accompaniment to the routine hot filtration methods. It can identify potentially troublesome unstable fuels even when the Hot Filtration Test methods indicate a low sediment content.   Conversely, it may indicate that a high sediment fuel is in fact quite stable and unlikely to form sludge. This information in combination, is extremely useful from an operational perspective, as it will indicate in advance if and what mitigation steps are appropriate.

VPS: Key steps in avoiding risk of receiving bad bunker fuels

Chemical Contamination

Over the years chemical contamination of marine fuels has resulted in many onboard operational issues, with numerous chemicals and chemical groups being identified as the cause. Major widespread contamination events, include Houston (2018), with over 200 vessels damaged due to a potential phenolic contamination, to Singapore (2022) where 80 vessels were affected by chlorinated hydrocarbons within the fuel and then more recently ARA (2023) where around 20 vessels suffered issues due to a cocktail of styrenes and dienes within the fuel. In between such times, many smaller cases of chemical contamination have been identified by VPS. Thankfully, many at a pre-burn stage, thus avoiding any operational issues or damage cases.

Over time, all of the following chemicals have been found by VPS in marine fuels. The effects of these are highlighted below:

VPS: Key steps in avoiding risk of receiving bad bunker fuels

Risks from chemical contamination of fuel can be significantly mitigated through pre-burn screening of fuels using VPS Chemical Screening Service. This low-cost test, utilising Gas Chromatography Mass Spectrometry (GCMS) analysis, will warn of the presence of over 70% of all volatile chemicals within fuel. With both VLSFO and HSFO we continued to see cases of vessel damages due to chemical contamination during 2023. Focusing specifically on the VPS GCMS-Head Space Chemical Screening service, as a damage prevention service, 19.9% of applicable marine fuel samples received by VPS since 2018, have undertaken this rapid, pre-burn protection service, with an average 8% of samples tested, giving rise to a “Caution” result, indicating the presence of at least one chemical contaminant and thus the notified vessel has avoided any damages.

In April 2023, a Singaporean-owned chemical and product tanker bunkered 415 m/tons of VLSFO in Houston. The vessel began to burn the fuel in May and quickly began to experience numerous issues with the auxiliary and main engines, such as exhaust gas deviating temperatures and the wearing of fuel pumps and plunger barrels. In addition, problems such as start-failure due to insufficient fuel injection, pressure build up, as well as worn out and leaking fuel pumps.

Of greater concern was the complete engine stoppage enroute to the next US port, when the main engine failed. Multiple attempts were made to start the engine, all without success.

Subsequent VPS forensic laboratory testing, utilising a proprietary Gas Chromatography Mass Spectrometry (GCMS) Acid Extraction methodology, detected the presence of several phenols and fatty acid compounds within the fuel.

The vessel initiated the necessary repairs to both auxiliary and main engine fuel pumps, at a total spares cost of $200,000. In hindsight the vessel owner stated pre-burn screening would have helped significantly in avoiding such damages and costs.

Cold-Flow Properties

VPS: Key steps in avoiding risk of receiving bad bunker fuels

The cold-flow properties of fuels are also important to monitor closely, especially when sailing in colder temperature regions. The Pour Point of HSFOs, VLSFOs and MGO fuels, should always be monitored when colder climates are encountered. Pour Point was the most common MGO off-specification parameter in 2023, with 36.6% of MGO off-specs attributed to Pour Point. However, prior to reaching the pout point of MGO fuel, its cloud point and cold-filter plugging point behaviour offer earlier warning-signs of potential cold-flow issues, relating to wax precipitation from the fuel. It is key fuel management practice to measure these two cold-flow parameters within MGO distillates.

VLSFO fuels have a higher paraffinic content than HSFO and as a consequence, have a greater potential to precipitate wax, which can cause filter and pipework blockages, which can ultimately starve an engine of fuel. As VLSFOs are dark fuels, the cloud point cannot be seen, as it can with a distillate fuel. Therefore in 2019, VPS developed a proprietary test method to measure the Wax Appearance (WAT) and Wax Disappearance Temperatures (WDT) of VLSFOs.

Generally, it is recommended that the fuel temperature is kept approximately 10oC above the PP to avoid risk of solidification. However, in the majority of the global bunker ports in 2022-23 the average WAT was often higher than 30oC, and WDT higher than 40oC. This may also mean heating the fuel to avoid solidification during transfer. However, this should not necessarily mean an increase in storage temperature. Fuel oil transfer pumps on board are generally positive displacement pumps and can handle certain amount of wax that are present in the fuel.

If the fuel has a high WAT/WDT, VPS recommend heating the fuel just before the transfer operation.

VPS: Key steps in avoiding risk of receiving bad bunker fuels

Therefore, additional fuel tests, such as, Total Sediment Existent (TSE), Separability Number (Reserve Stability Number, RSN), Wax Appearance/Wax Disappearance Temperature Testing, Cloud Point, Cold Filter Plugging Point and Chemical Screening, can provide significantly greater and more valuable protective information, when assessing fuel quality than ISO8217 alone. This is why VPS offer our Additional Protection Service (APS) “bundles”. The APS includes the standard ISO8217 parameters but also fuel-relevant additional tests, in order to support our customers to greater levels with respect to, asset, crew and environmental protection.

Over the years, VPS Off-specification fuel data has proactively highlighted the potential risks associated with certain parameters. The importance of regular and wider-ranging marine fuel testing, through the Additional Protection Service, will definitely support mitigation strategies to prevent disruptions in vessel power supply due to fuel-related issues. Even a minor fuel quality issue can prove costly. A 2018 report by the Swedish Club highlighted the average cost per incident of fuel-related damage on vessels is $344K.


Photo credit: VPS
Published: 9 April 2024

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Fuel Testing

Singapore: CTI-Maritec shares testing protocols ahead of mandatory enhanced bunker fuel checks

In light of mandatory enhanced checks for marine fuel delivered at Singapore port coming into effect on 1 June, CTI-Maritec shares recommendations for fuel testing protocols, primarily focused at COCs and SAN detection for bunker supply in Singapore.





Louis Reed from Unsplash

With mandatory enhanced checks for marine fuel delivered at Singapore port coming into effect on 1 June, bunker fuel testing and marine surveying business Maritec Pte Ltd (CTI-Maritec) has published a newsletter providing recommendations on vital pre-emptive fuel testing measures vessels should be taking as part of their routine fuel testing and also recommendations on optimal testing options available when deep-dive analysis is required to determine a root cause: 


On 8 February 2024 the Maritime and Port Authority of Singapore (MPA) issued a Port Marine Circular No 3 of 2024 regarding the implementation of enhanced testing parameters for marine fuel batches intended to be delivered as bunkers in the Port of Singapore in addition to the existing quality assurance measures.

In accordance with the MPA’s Port Marine Circular No 3 of 2024, from 1 June 2024 onwards, bunker suppliers in the Port of Singapore must ensure that:

  • Residual & Bio-residual bunker fuel do not contain Chlorinated Organic Compounds (COC) above 50mg/kg and are free from inorganic acids.
  • COC must be tested using the EN 14077 accredited test method and shall be reported in the “Certificate of Quality” (COQ) provided to receiving vessels.
  • Inorganic acids must use the ASTM D664 accredited test method as prescribed in ISO 8217 and the Strong Acid Number (SAN) (in addition to the Total Acid Number (TAN) shall be reported in the COQ (i.e. SAN = 0) provided to receiving vessels. For distillate / bio-distillate bunker marine fuel batches, SAN must be tested as per ASTM D664 test method and reported in the COQ.
  • Residual marine fuels are free from polystyrene, polypropylene & polymethacrylate. These can be tested by filtration, microscopic examination, & Fourier-Transform Infrared spectroscopy analysis.

Testing Recommendations in line with MPA Enhanced Parameters to Protect Your Vessels:

In view of the above, CTI-Maritec recommends fuel testing protocols as depicted in the chart below (as routine pre-emptive measures and/or for deep dive requirements to detect the root cause) to help safeguard vessel health.

Our recommendations are primarily focused at COCs and SAN detection for bunker supply in Singapore, while recommendations for testing Polymers are advised for requirements of reported problem cases or when highly abnormal GCMS findings of chemical compounds like Styrene, DCPD and Indene are detected.

COC & SAN GCMS testing Packages A to E

Related: Singapore: CTI-Maritec publishes whitepaper on upcoming mandatory enhanced bunker fuel tests
Related: Singapore: Marine fuel quality testing agencies applaud move for mandatory enhanced bunker fuel tests
Related: Singapore: MPA tightens testing parameters to reduce contaminated bunker fuels
Related: MPA: Glencore and PetroChina supplied contaminated bunkers to about 200 ships in the Port of Singapore


Photo credit: Louis Reed from Unsplash
Published: 29 May 2024

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VPS conducts assessment on first SIMOPS methanol bunkering op in Singapore

Firm was appointed by OCI Methanol Europe to conduct a quantity and quality assessment of a methanol bunker fuel delivery to “Eco Maestro” in Singapore.





VPS conducts assessment on first SIMOPS methanol bunkering op in Singapore

Marine fuels testing company VPS on Tuesday (28 May) said it was appointed by OCI Methanol Europe, part of the OCI Global Group, to conduct a quantity and quality assessment of a methanol fuel delivery to Eco Maestro in Singapore.

Captain Rahul Choudhuri, President Strategic Partnerships, VPS, said VPS survey experts Rafael Theseira and Muhd Nazmi Abdul Rahim were at hand during the methanol bunkering to ensure the 300 metric tonnes of methanol transfer was carried out smoothly, having been involved in the first methanol bunkering a year ago. 

Manifold Times recently reported X-Press Feeders, Global Energy Trading Pte Ltd (GET), and PSA Singapore (PSA) successfully completing the first simultaneous methanol bunkering and cargo operation (SIMOPS) in Singapore.

A X-Press Feeder container vessel, Eco Maestro, on its maiden voyage from Asia to Europe was successfully refuelled with close to 300 mt of bio-methanol by GET, a MPA licensed bunker supplier, using MT KARA

The ISCC-certified bio-methanol used for the SIMOPS was produced by green methanol producer OCI Global and supplied via GET, a ISCC-certified supplier.

Captain Choudhuri said the role of the marine, petroleum or bunker surveyor has evolved over the years in shipping and maritime affairs, but the principles have not - and that is to provide independent assessment of the quality and quantity of the product transfer. 

“This may seem obvious but this quality and quantity control is crucial to avoid commercial discrepancies, shortages or fraud,” he said.

“Safety training is critical and we have been on top of this having completed the required MPA fire-fighting course and the IBIA Methanol training course. We will work more with the Singapore Maritime Academy for trainings in future,” he added.

In August last year, Singapore-headquartered independent common carrier X-Press Feeders launched its first ever dual-fuel vessel Eco Maestro in China.

Manifold Times previously reported VPS stating it was the first company to complete a methanol bunker quantity survey (BQS) operation in Singapore on 27 July last year.

VPS was appointed by Maersk and Hong Lam Marine Pte Ltd, to undertake the very first bunker quantity survey (BQS) of a methanol fuel delivery, supplied by Hong Lam to the Maersk vessel on its maiden voyage to Europe. 

Related: First SIMOPS methanol bunkering operation completed in Singapore
Related: VPS completes quantity survey on Singapore’s first methanol bunkering op
Related: Singapore bunkering sector enters milestone with first methanol marine refuelling op
Related: X-Press Feeders launches its first methanol dual-fuel vessel “Eco Maestro” in China


Photo credit: VPS
Published: 29 May 2024

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Bunker Fuel

FOBAS issues industry update of new ISO 8217:2024 marine fuel specifications

FOBAS points out there are a number of significant changes to ISO 8217 as compared to 6th (2017) edition both in terms of extent and content.





RESIZED Hans Reniers on Unsplash

Lloyd’s Register Fuel Oil Bunkering Analysis and Advisory Service (FOBAS) on Thursday (16 May) released a bulletin to highlight significant changes to the ISO 8217:2024 as compared to the 6th (2017) edition.

This bulletin is to bring all clients' attention to the imminent publication of the new version of ISO 8217 and we will be updating again as soon as ISO secretariate uploads the final version of ISO 8217:2024 on its website.

The increasing demand of environmental legislation is leading a marine fuel transition towards oil products derived from synthetic and renewable, recycled or alternative sources. There are a number of significant changes as compared to the 6th (2017) edition both in terms of extent and content.

  • The most noticeable change is to the residual grades in that these will now be divided into three separate tables
    • 4 RM grades not exceeding 0.50% or 0.10% sulphur,
    • 5 RF (biofuel) grades covering unrestricted % FAME content
    • 5 RM grades above 0.50% sulphur.
  • Similarly for the distillates each of the grades, apart from DMX, has a corresponding FAME blend version of unrestricted %
  • In the case of the FAME blends, residual or distillate, the percentage of FAME component is to be advised to the receiver at delivery
  • The FAME used is generally to have met either the EN 14214 or ASTM D6751
  • The net specific energy is to be reported by the supplier
  • Suppliers to ensure all fuel grades are free of organic chlorides
  • Each of the category tables now includes specific reference to the normative paragraphs of the standard
  • The principal change to the residual grades is that these all now also include a minimum, in addition to the existing maximum, viscosity
  • To enhance control of asphaltene stability in the case of sulphur limited RM grades and the RF grades, this is now limited in terms of total sediment by thermal ageing to the same limit as before but additionally the accelerated and existent values are also to be reported by the supplier

It is also worth noting that generally the limit values, for both the distillates and residuals, have not fundamentally altered although for residuals there has been a redistribution across the reduced number of grades.

Lloyd’s Register FOBAS has been heavily involved in guiding and contributing as a member of the ISO and CIMAC fuels working groups and for our position we would highly recommend adopting this new standard in all fuel purchasing/sourcing processes whenever possible. We will have a number of additional testing options available which we will further explain on request.

As mentioned, a far more detailed bulletin will be issued shortly supported by a list of FAQ to further support your operations.


Photo credit: Hans Reniers on Unsplash
Published: 17 May 2024

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