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IMO 2020: Bunker tank cleaning and preparation to receive compliant fuel

The Standard Club offers tips on various cleaning methods and advises members to start preparations.

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The Standard Club on Thursday (18 July) published an article regarding the cleaning and preparation of vessel bunker tankers to receive IMO 2020 compliant fuel. The article has been shared with Manifold Times:

Introduction

To achieve compliance with the sulphur cap, simply switching to a low sulphur fuel at January 2020 will not be enough. High sulphur fuel oil (HSFO) is primarily based on residual fuel and these tend to stick to the inside of fuel tanks and pipelines forming layers of sludge and sediments.

The accumulated layers of existing sludge in the fuel tanks and pipelines may contaminate the new fuel loaded, rendering the fuel non-compliant and pushing emissions above the 0.50% sulphur cap. Cleaning this out will require exhaustive efforts – either manually which is risky, expensive and time-consuming, or with specialised fuel treatments (chemical additives).

As such, members who have chosen to achieve compliance with MARPOL Annex VI regulations by using low sulphur fuel oil, will need to start preparatory and precautionary steps several months ahead of the regulatory enforcement date.

This process is also an important measure to avoid compatibility and stability issues while transitioning to 0.50% m/m compliant fuel from high sulphur fuel oil (HSFO).

Planning

Options for preparing fuel oil tanks for compliance include flushing through fuel systems, manual cleaning of tanks during dry docking, manual cleaning during service or cleaning tanks in service with specialised additives.

The process of fully cleaning and flushing fuel oil tanks and piping systems requires advance planning; and at a minimum, the plan should provide guidance on:

  • fuel oil tank capacity and segregation capability for different fuel grades
  • fuel oil system modifications (if needed)
  • assessment of the new fuels on engines and machinery (compatibility testing)
  • fuel oil changeover plan
  • risk assessment and mitigation plan. 

It is also prudent to consult the engine maker on the appropriate method of preparation of the bunker fuel oil tanks and flushing of fuel oil piping system.

The overall fuel oil management plan, including tank cleaning/preparation procedures, should form a part of the ship implementation plan (SIP), taking into consideration the ship’s trading pattern, docking etc.

While the supply of fuel is the charterer’s responsibility, the responsibility of managing it onboard will be for the owner. As such, shipowners are recommended to reach an agreement with their charterers on when to undertake tank cleaning and purging of the fuel oil lines because the vessel may have to be taken out of service for some days.

Such agreement should cover scenarios when the ship is supplied with a non-compliant fuel oil – as post-2020, not all ports will provide discharge facilities for the reception of the high sulphur fuel oil. Even if discharge facilities are available, costs may need to be incurred for cleaning of the fuel oil tank before loading compliant fuel oil to avoid contamination.

Cleaning methods

Manual cleaning during dry-docking

The advantage with this method is that a ship will undergo cleaning of all its fuel oil tanks and fuel service systems and will be able to start loading compliant fuels and expect to be fully compliant right away.

The time required for manual cleaning of fuel oil tanks in shipyards may vary depending on the advance preparation carried out, tank condition (amount of remaining sludge) and efficiency of the chosen shipyard. In addition to the cleaning of tanks, all the pipework in the fuel oil transfer and service system would need to be flushed through thoroughly.

Manual cleaning while the ship is in service

If tanks are to be cleaned manually during service, risk assessment and safety measures for entering enclosed spaces would need to be specially considered and managed. The risk assessment and mitigation plan will also need to consider the handling of tank cleaning equipment and associated hazards.

The factors affecting the time required are similar to the manual cleaning in shipyards, except in this case a lot would depend on the number of crew available to perform the task. The tanks need to be empty before they can be cleaned. While the ship is in service, this would mean transferring the tank contents to a designated tank for final consumption or temporary storage and subsequent removal. The residues from tank cleaning will need to be retained on board until they can be properly disposed to shore reception facilities.

Cleaning by specialised fuel treatments (chemical additives)

Cleaning the sediments and sludge from bunker tanks and fuel systems by chemical additive doses could be considered as an alternative to manual cleaning. Use of such additives usually involves a gradual clean-up period conducted over a few bunker cycles prior to loading compliant fuel. This ensures a smooth system clean-up by preventing excessive sludge blockages. As such products would be dosed directly into the fuel tank, it would clean the whole fuel oil service system, including settling and service tanks. However, depending on the amount of accumulated sludge inside the tanks and potency of the chemical additives, it may take several months for the tank to be clean.

Members are advised to take proper consultation with chemical additive manufacturers and engine makers to ensure that the chemical additives have no adverse impact on the ship’s machineries.

Recommendations

With the 2020 deadline approaching, members need to be mindful that preparations for accepting any new compliant fuel would need to start well in advance.

Ship implementation plans need to include all such considerations and calculations for the time needed for ships to be fully flushed of all fuel oils exceeding the applicable sulphur content prior to entry into force of the regulation.

Source: The Standard Club
Published: 22 July, 2019

 

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Ammonia

AM Green plans to build green ammonia plant at Indian port

Initiative also includes development of green ammonia handling, storage and bunkering infrastructure, pilot bunkering operations, safety procedures and training programmes, says VOC Port Authority.

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VO Chidambaranar (VOC) Port Authority on Friday (29 May) said it has signed a Memorandum of Understanding (MoU) with India’s ammonia producer AM Green Ammonia to collaborate in the development of a green ammonia production plant.

The plant will have a capacity of one million tonnes per annum (MTPA) at Tuticorin.

The initiative also includes development of green ammonia handling, storage and bunkering infrastructure, pilot bunkering operations, safety procedures and training programmes. 

The project is expected to support the development of green fuel corridors connecting VOC Port with major ports in Europe and Asia, thereby strengthening India’s position in the global green fuels value chain.

VOC Port also signed a Memorandum of Understanding (MoU) with Bureau Veritas (India) Pvt. Ltd., to collaborate on Green Port certification, emissions accounting, ESG reporting, safety validation, development of green bunkering practices, and establishment of a Centre of Excellence for green fuels and sustainability.

The port also plans for an upcoming 750 m³ green methanol bunkering facility.

 

Photo credit: Naveed Ahmed on Unsplash
Published: 3 June, 2026

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Port & Regulatory

Study: Major drop in ship sulphur emissions confirmed following IMO regulations

National Centre for Atmospheric Science study found that the average sulphur content in ship fuel dropped nearly tenfold in open ocean areas following IMO’s 2020 regulation.

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Recent global regulations have significantly reduced sulphur emissions from ships, helping to improve air quality in coastal regions – confirmed by a recent international study led by researchers at the National Centre for Atmospheric Science. 

The research, published in Environmental Science: Atmospheres, used aircraft and ground-based instruments to measure sulphur dioxide and nitrogen oxides emitted by ships in the North-East Atlantic and European coastal waters between 2019 and 2023.

The team found that the average sulphur content in ship fuel dropped nearly tenfold in open ocean areas following the International Maritime Organization’s 2020 regulation, which capped sulphur content in marine fuel at 0.5%. 

Before the change, many ships exceeded the previous 3.5% limit. After 2020, only a small number of ships were found to breach the new standard.

In European sulphur Emission Control Areas (SECAs), such as the English Channel and the Port of Tyne, sulphur levels were even lower – well below the stricter 0.1% limit. Interestingly, ports outside these zones, like Valencia in Spain, also showed low sulphur levels, likely due to EU rules requiring cleaner fuel when ships are docked for extended periods.

This is the first study to use aircraft-based measurements and predictions from the Ship Traffic Emission Assessment Model (STEAM3) to assess ship emissions outside of sulphur control zones since the 2020 regulation came into effect. The findings support the widely held view that ships now emit around seven times less sulphur than before the rule change – an important step toward cleaner air and healthier coastal environments.

Note: The research, titled ‘SO2 and NOx emissions from ships in North-East Atlantic waters: in situ measurements and comparison with an emission model’ can be found here. 

 

Photo credit: shraga kopstein on Unsplash
Published: 8 December, 2025

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Interview

IBIA Annual Convention 2025: ‘Exciting times’ for post IMO 2020 bunker suppliers, states Equatorial

Choong Sheen Mao, Chief Operating Officer, Equatorial, describes to Manifold Times the pre/post IMO 2020 challenges and evolution of bunker suppliers.

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The International Bunkering Industry Association (IBIA) will be hosting its flagship Annual Convention in Hong Kong at the Hong Kong Convention Exhibition & Convention Centre between 18 to 20 November 2025, as part of Hong Kong Maritime Week.

Choong Sheen Mao, Chief Operating Officer, Equatorial Marine Fuel Management Services (Equatorial), speaks to bunkering publication Manifold Times about the challenges of a post IMO 2020 bunker supplier.

MT: How does Equatorial continue to offer customer assurance and maintenance of marine fuel quality to ISO8217 standards despite increasing complexity of bunker fuel blends?

We maintain our focus to provide compliant, quality and competitively priced products to our customers. There is no shortcut. We source our products from a wide range of cargo producers and suppliers. We continue to be strict and vigilant with our testing programme for our products before delivering them to our customers. Equatorial has deepened our engagement with the wider industry to have a better and up-to-date understanding of the existing and new marine fuels.

MT: Can you share the evolution of commercial marine fuel procurement, blending and trading strategies on the back of increasing fuel types (pre/post IMO 2020)?

Pre IMO 2020, the main types of marine fuel procured and consumed by vessels were high-sulphur fuel oil, marine diesel oil and marine gas oil. Trading strategies were therefore closely linked to that within the oil industry.

However, many of the new fuel types are from other industries. For example, biofuels, methanol and ammonia are mainly products from the chemical and agriculture industries. There are marked differences between these industries and the energy industry (in particular, the marine fuels industry). LNG is from the gas industry which is distinct from the oil industry.

Without an existing liquid paper market for many of these commodities (especially as a marine fuel), the price risk management is less straightforward. Furthermore, commodity prices are no longer the sole consideration for price itself. The price of compliance must be considered. This could range from guaranteeing the origin of the marine fuel, its sulphur properties as well as its carbon intensity. The list goes on.

MT: Operational wise, what are the changing role and responsibilities of a bunker supplier to date, compared to before IMO 2020?

The role and responsibility of a bunker supplier have evolved. Fundamentally, it has been about providing quality marine fuels at competitive prices. Quantity assurance has been a critical concern which led to the mandatory implementation of the mass flow meter system for bunkering in the Port of Singapore. Interestingly, due to the nature of credit terms in the bunker industry, bunker suppliers also performed the role of “bankers” by extending favourable credit terms to shipowners and charterers.

These days, post IMO 2020, things have become even more complicated. Today, a bunker supplier retains the abovementioned roles and responsibilities, and much more – it has to ensure compliance with a plethora of rules and regulations. Compliance not only with sulphur cap requirements, but with international and regional sanctions and restrictions unrelated to the quality of the marine fuel itself. In fact, especially with alternative low- and zero-carbon marine fuels, this means compliance with standards, rules and regulations on sustainability such as the European Renewable Energy Directive and/or International Sustainability and Carbon Certification. There is also the need to comply with increasingly stringent safety regulations on both conventional and alternative marine fuels.

In addition to the above, a post IMO 2020 bunker supplier is still expected to supply compliant and quality fuel at competitive prices.

MT: Equatorial is Singapore’s largest local-born supplier; what is the next big thing for the company?

Equatorial continues to adapt and improve with the times, while maintaining its core values – Integrity, Teamwork, Commitment, Proficiency and Quality, and Safety and Environment. The bunker industry is a highly competitive one, and it is our intention to keep our competitive edge and remain relevant. This means that we have had to step out of our comfort zone and embrace the two mega trends of our time – digitalisation and decarbonisation.

We have been early adopters and developers of the electronic bunkering note as part of our own digital bunkering efforts. We have diversified our product offering to include low carbon marine fuels and are proud to be one of the pioneers for bunkering B100 biofuels earlier this year. This was made possible by the arrival of our IMO Type II chemical and oil bunker tankers. These same bunker tankers are also capable for carrying and delivering methanol. Equatorial has invested in an LNG bunkering vessel (LBV) newbuilding that is set to be delivered in Q3 2027. We are also involved in a study to develop low- or zero-carbon ammonia bunkering in Singapore.

These are exciting times.

Note: Choong Sheen Mao is amongst panellists featured in ‘Session Three: Bunker Sellers Panel’ at the IBIA Annual Convention 2025.

Join the Conversation

With over 300 delegates expected, the IBIA Annual Convention 2025 is set to be a defining moment for the marine fuels industry. Registration is now open via the IBIA Annual Convention website.

 

Photo credit: Manifold Times
Published: 31 October 2025

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