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IMO 2020

Skuld: MARPOL annex VI – Sulphur Cap 2020 – Tank cleaning guidance

Explains to shipowners details on preparing and cleaning vessels’ bunker tanks in preparation for IMO 2020.

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Maritime insurance agency Skuld on Thursday (25 July) published the following article explaining to shipowners the details on preparing/cleaning vessels’ bunker tanks in preparation for IMO 2020:

The majority of ships are expected to use distillate fuel 0.50% sulphur limit taking effect on 1 January 2020. Most of these ships will have been using high viscosity High Sulphur Fuel Oil (HSFO) based primarily on residual fuel oils.

Such fuels tend to stick to the inside of fuel tanks forming layers of semi-solid substances containing sediments and asphaltenic sludge. Such residues will also typically have solidified and settled in various parts of the fuel oil service system including pipelines, settling and service tanks.

Chemicals additives are used by some shipping companies to clean their tanks prior to change in use. It can prove to be very efficient and a cost-effective way to reduce the tank cleaning. We all know of the imposing 1 January 2020 date for tank preparation.

Fuel oil tanks should be cleaned on regular basis to remove build-up of sediments and sludge, usually during dry docking or whenever inspections of the fuel tanks are due.

However, leading up to 1 January 2020 it would not be practicable for the majority of the global fleet that has been running on HSFO to undergo dry docking during a very short period. Therefore, other options for cleaning tanks and fuel oil systems during service need to be considered.

Unfortunately, the time and work involved in preparing HSFO tanks to fuel complying with the 0.50% sulphur limit cannot be defined precisely as it will vary depending on:

• the length of time since the last cleaning of the tanks;
• the condition of the tank coating and the effectiveness of the cleaning process itself.

The estimates in this article may err on the side of caution as it is almost impossible to pinpoint at what stage the ship’s fuel oil system is sufficiently clean to guarantee compliance.

Then again, timings vary from vessel to vessel but on average cleaning can be done in two to four days per tank.

In addition to cleaning the tanks, all of the pipework in the fuel oil service system needs to be flushed thoroughly. Overall it may take up to two weeks per vessel.

A vessel that has had all its fuel oil tanks and fuel system cleaned can start loading compliant fuels and expect to be fully compliant right away. However, if the tanks have been cleaned in dry dock, it could take two to five days to flush through the pipework and this step should not be underestimated.

If tanks are to be cleaned manually during service a risk assessment and adoption of safety measures are paramount.

Time required will vary depending and the number of crew available to perform safe and complete tank cleaning operations. Tank cleaning can be performed by the ship’s crew or by employing a riding crew. If the cleaning is done by the ship’s existing crew, it would be likely to take a minimum of 4 days per tank. Tanks need to be empty before they can be cleaned, hence the time needed to drain tanks needs to be taken into account when estimating the overall time required.

The residues from tank cleaning should be retained on board until they can be disposed of correctly, for instance at shore reception facilities.

An alternative to manual cleaning is to gradually clean the sediments and asphaltenic sludge from HSFO tanks and fuel system by dosing specialised additives resulting in less sludge. This is a soft and easy way to clean the tanks.

Sulphur 2020 cap will impact the fuel supply chain, procurement and operational safeguards. The impact is happening now, so act on any identified gaps, e.g. crew training in fuel management, preparation for efficient and cost saving tanks cleaning during service and preparing all HSFO tanks to load compliant fuel.

Note: This text is based on IMO guidance on the development of Ship Implementation Plan (MEPC. 1/Circ.878)

Source: Skuld
Photo credit: Manifold Times
Published: 29 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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