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Innospec highlights important overview on handling fuel instability issue of VLSFO

Majority of VLSFO components come from low cost distillate and low sulphur petrochemical streams which can be readily separated to form distillate sludge.

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Colorado-based global specialty chemicals company Innospec has published an article on handling fuel instability of very low sulphur fuel oil (VLSFO) in their February technical bulletin :

Problems associated with VLSFO

  • Polished liners, Piston ring failure
  • Instability / compatibility
  • Fuel injector / pump damage
  • Low combustion efficiency
  • Post combustion fouling (Turbochargers, EGE, EGR, SCR, scrubbers/wash water)
  • Short storage lifespan
  • Reduced service intervals (purifiers)

What is Fuel instability and why is it more important than ever?

HSFO instability meant Asphaltenes dropped-out of solution causing filter blocking, tank fouling, poor combustion and increased purifier cleaning/servicing frequency. VLSFO still contains Asphaltenes from residual streams; however, it is a different animal. The majority of VLSFO components come from low cost distillate and low sulphur petrochemical streams which can be highly volatile, these can separate readily to form distillate sludge such as sticky gums, hard sediments or even polymers in storage/handling tanks, filters, pipework, purifiers and mechanical contact surfaces.

It has been shown that after-burn and dumb-bell ignition (both early and late ignition) are a high risk due to the incompatible mixture of light (paraffinic) and heavy (Asphaltenes) fractions used to achieve lower costs and 0.5% Sulphur found in VLSFO. Using the best methods for component mapping and stability monitoring we have proven the blend of two dissimilar components pose a significant risk of instability through rapid chemi-cal ageing, this makes storage/handling unpredictable with some of the effects being unavoidable on-board. 

Distillate sludge blocks filters and purifiers just as residual sludge does, only this can happen rapidly for a variety of reasons including prolonged storage (>1 month), heating or co-mingling. Unfortunately, it can also happen due to an inherent instability, which leads to chemical changes in the fuel once on-board.

The true risk of distillate sludge is to ships engines. Paraffinic gums are highly adhesive and stick to contact surfaces such as injectors and fuel pumps. Once established they allow hardinorganics such as metals/cat fines to become imbedded within, creating an abrasive surface that wear down fine tolerances, or create blockages. The quick onset of injector nozzle blockage leading to poor spray pattern and ignition efficiency which will lead to greater instance of liner impingement, after- burn and post combustion fouling (soot, ash, T/C deposits).

What does this mean for combustion?

Asphaltenes have always existed within Marine Fuels, they have a high calorific value and burn readily if effectively dispersed within the fuel; if stabilised the Asphaltenes are dispersed and protected by naturally occurring resins, which keep them small enough to find sufficient oxygen and burn during combustion. By contract, VLSFO can be an overly refined product containing low cost distillate streams that strip-away protective resins causing the Asphaltenes to agglomerate to form huge complex structures, which drop out of solution. Those that are not removed during filtration or purification or develop afterward are injected into the combustion chamber but are too large to burn effectively. This is when we see ‘black’ residual deposits on liners and pistons from unburnt fuel.

The same is true of distillate sludge, only that we have seen that these tend to effect engine components far more than Asphaltenes. Once injector efficiency is reduced through nozzle blockage, early ignition or contact surface wear, this leads to poor spray pattern and further compounds poor combustion efficiency.

How do we keep ships sailing?

Fuel handling practices will need to change to face the new challenges; unfortunately, each fuel bunkering will vary significantly from region to region or even within the same port. VLSFO is still a residual fuel that requires heating due to high pour points, variable viscosity and waxy distillate components. Unfortunately heating VLSFO can lead to the rapid onset of aging, which brings us instability. There are cases where fuel has polymerised within four hours of leaving the storage tank and entering the fuel handling system (with purifier temperatures as low as 60°C!). These chemical reactions cannot be avoided even when good on-board practices are followed.

Innospec were approached by Industry to develop OctamarTM HF-10 PLUS; our expertise in the Marine, Automotive, Aviation and Refinery business uniquely places us in a position to maximise the operability of fuels. 

OctamarTM HF-10 PLUS contains our famous Asphaltenes dispersant/stabiliser which has been used in over 3000 vessels world-wide to clean-up and maintain fuel tank cleanliness, and our unique distillate stabiliser/detergent and dispersant, which targets problem elements in the low quality distillate streams, preventing them from propagating into sludge or adhering to machinery contact surfaces.

This means clean tanks, filters, purifier, engines and better combustion. Our formulas have been a must-have in automotive/industrial diesels and long-term storage units for decades and we are pleased to bring it to the marine sector in these trying times.

OctamarTM HF-10 Plus chemically targets problem elements within the fuel, cleaning up Asphaltenes, distillate gums and sediments, and prevents the onset of polymerisation and oxidation.

Would you like to know more?

To find out more details please contact our technical team in your region and visit our website:

For Europe, Middle East and Africa mail [email protected]

For Asia Pacific mail [email protected]

For America mail [email protected]

Related: Innospec launches Octamar™ series of additives for new blends of IMO 2020 bunker fuels


Photo credit: Innospec
Published: 17 February, 2020

 

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Legal

Singapore police arrest eight over alleged illegal MGO transaction off Tuas

SPF says preliminary investigations found that crew members of a Singapore-registered tugboat misappropriated MGO worth about SGD 10,570 without their company’s knowledge and sold it illegally.

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Singapore police arrest eight over alleged illegal MGO transaction off Tuas

The Singapore Police Force (SPF) on Thursday (13 August) said it has arrested eight men, aged between 25 and 54, for their suspected involvement in an illegal transaction of Marine Gas Oil (MGO).

On 13 August 2026 at about 1.05am, officers from the Police Coast Guard (PCG) conducted a check on a Singapore-registered tugboat in the waters off Tuas and discovered that eight crew members were possibly involved in the illegal transaction of MGO. 

“Preliminary investigations revealed that the crew members of the tugboats misappropriated MGO valued at about SGD 10,570 (USD 8,258), without their company’s knowledge,” SPF said in a statement.

“The MGO was sold illegally for their personal financial gain.”

The eight crew members will be charged in court on 14 August 2026 with the offence of theft by servant of property in possession of master under Section 381 of the Penal Code 1871 If convicted, they shall be punished with an imprisonment term that may extend to seven years and shall also be liable to fine.

“The Police take a serious view of illegal transaction of MGO in Singapore Territorial Waters and will continue to conduct enforcement and security checks to prevent, deter and detect such illicit activities in Singapore waters,” SPF added. 

 

Photo credit: Singapore Police Force
Published: 14 August, 2026

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Port & Regulatory

Gard: Sulphur-related bunker claims rise amid tighter China MSA enforcement

Claims involving excessive sulphur content in marine fuels have been rising, while stricter inspections by the China MSA have heightened the focus on sulphur compliance, particularly in the Bohai Sea.

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Maritime protection and indemnity (P&I) club Gard on Wednesday (12 August) highlighted that claims involving excessive sulphur content in marine fuels have been rising, while stricter inspections by the China MSA have heightened the focus on sulphur compliance, particularly in the Bohai Sea:

Rise in off-spec sulphur claims

Recent claims experience indicates that bunker quality continues to pose a significant operational risk for shipowners. In our earlier review of bunker-related claims during the first five months of 2026, we highlighted a rise in off-specification bunker incidents amid increased pressure on global fuel supply chains following the escalation of the conflict in the Middle East. 

Specifically for Sulphur compliance, between January and June 2026, the number of sulphur-related cases increased by more than threefold compared with the same period in 2025. Notably, the number of cases recorded in the first six months of this year has already exceeded the total number reported during the whole of last year by approximately 40%. 

While each case is fact-specific, the increase is notable because excessive sulphur content constitutes a MARPOL compliance issue. Unlike many other bunker quality problems, sulphur non-compliance identified through port state inspections can result in vessel delays, enforcement action, and substantial costs associated with debunkering and fuel disposal. 

The map below illustrates the geographical distribution of sulphur-related claims recorded during the first six months of 2026, based on the location where the bunkers were stemmed.

Distribution of sulphur related claims

China MSA steps up sulphur compliance enforcement

According to our correspondent, Huatai, on 5 June 2026, the maritime authorities of Tianjin, Hebei, Liaoning and Shandong jointly launched a special campaign on ship pollution prevention and control in the Bohai Sea region. The campaign involves coordinated supervision by local MSA branches across the region and is expected to last nearly five months. It covers major ports and surrounding port areas in the Bohai Sea region, including Tianjin, Tangshan, Qinhuangdao, Huanghua, Jinzhou, Yingkou and Longkou. 

While the initiative is broader than bunker sulphur compliance alone, its scope includes inspections relating to air pollution prevention, SOx emissions, fuel compliance and other high-pollution-risk operations. Enforcement measures are expected to comprise onboard inspections, cross-regional enforcement activities, unannounced spot checks and remote monitoring. These efforts will be supported by a combination of UAV patrols, maritime patrol vessels, shore-based monitoring systems and rapid on-site fuel testing. 

As a result, vessels trading in the Bohai Sea region may experience increased scrutiny of fuel compliance documentation, fuel sampling records, onboard fuel management procedures, and the handling or disposal of suspected non-compliant fuel.

Documents typically requested by China MSA

Based on our recent experience, including the case discussed above, and subject to the specific requirements of the local MSA office, owners and operators may be requested to provide supporting documentation such as: 

  • Bunker documentation – Bunker Delivery Notes (BDNs), MARPOL fuel sample records, fuel test reports, and relevant fuel quality certificates. 
  • Statutory certificates – including the International Air Pollution Prevention (IAPP) Certificate and International Oil Pollution Prevention (IOPP) Certificate. 
  • Operational records – engine logbooks, deck and navigation logbooks, Oil Record Book entries, and records relating to fuel transfers, storage and consumption. 
  • Sampling documentation – the Master’s statement and any records demonstrating how fuel samples were drawn, sealed, labelled, handled and retained. 
  • Correspondence records – communications with the authorities, bunker suppliers, charterers and other relevant stakeholders. 
  • Fuel disposal records – approved disposal plans, debunkering documentation, receipts and evidence of final disposal, where applicable. 

The exact documentation required will depend on the nature of the investigation, the findings of the inspection, and the requirements of the local enforcement authority. 

Possible regulatory consequences in China

Under the Air Pollution Prevention and Control Law of the People’s Republic of China, ocean-going vessels are required to use fuel oil meeting atmospheric pollutant control requirements after berthing. Vessels operating within designated emission control areas must also comply with applicable emission standards. Article 106 provides that where vessel fuel oil fails to meet applicable standards or requirements, the competent maritime authorities may impose fines ranging from RMB 10,000 to RMB 100,000. Liability may extend to shipowners, ship operators and ship managers depending upon the circumstances of the case. 

Recommendation

Sulphur compliance should be treated as both a fuel quality and regulatory risk. Owners and operators are encouraged to take preventive steps before bunkering, act promptly if non-compliant fuel is suspected, and preserve evidence carefully if an inspection or claim arises. Under amended 

Resolution A.1206(34), Appendix 18, 2.1.5, if the BDN shows compliant fuel, but the master has independent test results of the fuel oil sample taken by the ship during the bunkering which indicates non-compliance, the master may document this by notifying the ship’s flag Administration, with copies to: 

  • the competent authority of the relevant port of destination, 
  • the Administration under whose jurisdiction the bunker deliverer is located, 
  • and to the bunker deliverer.

 

Photo credit: shraga kopstein on Unsplash / Gard
Published: 14 August, 2026

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LNG Bunkering

Shell expands LNG bunkering footprint in Spain with Valencia

As one of the region’s key maritime hubs, the company said Valencia expands the options available to shipowners seeking LNG supply along major shipping routes.

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Shell expands LNG bunkering footprint in Spain with Valencia

British oil giant Shell on Thursday (13 August) said Valencia has joined its growing network of bunkering locations, making LNG available as a marine fuel.

The successful completion of the first LNG bunkering operation in Valencia marked an important milestone for Spain and further strengthened Shell’s LNG supply capabilities across the Mediterranean. 

In a video shared by the company, bunkering vessel Alice Consulich was shown supplying an undisclosed volume of LNG to the container ship MSC Sabrina.

“As one of the region’s key maritime hubs, Valencia expands the options available to shipowners seeking LNG supply along major shipping routes,” Shell said in a social media post. 

Shell said the achievement reflected the strong collaboration across the maritime value chain, including MSC Mediterranean Shipping Company, the Port of Valencia and Fratelli Cosulich Group.

“We look forward to making more LNG bunker deliveries in Valencia and across the Mediterranean as LNG infrastructure and capabilities continue to expand,” the company said. 

 

Photo credit: Shell
Published: 14 August, 2026

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