Connect with us

IMO 2020

Gard informs on stability and compatibility of very low sulphur fuel oils

Highlights availability of new CIMAS guideline on mitigating issues in the supply chain and on-board ships.

Admin

Published

on

5de49a7641f4e 1575262838

Maritime P&I club Gard on Thursday (28 November) published an alert on the stability and compatibility of very low sulphur fuel oils, informing readers the availability of a new CIMAS guideline of mitigating these issues:

In order to meet increasing restrictions on the sulphur content in marine fuel as defined by MARPOL Annex VI Regulation 14.1.3, the characteristics of the blending component feedstocks, method of production and type of cutter stocks used may be different from those in use today. As a result, marine fuels post 2020, i.e. max 0.50% blended fuels, are expected to result in a wide range of fuel formulations and characteristics and, consequently, an increased risk of instability and incompatibility compared with most fuels currently being used.

The aim of the International Council on Combustion Engines’ (CIMAC) new guideline, Marine fuel handling in connection to stability and compatibility, is to provide a practical and working understanding of the definitions of stability and compatibility of residual marine fuel oils and how these two fuel properties may be best managed in the supply chain and on-board ships. The guideline also covers the accepted available test methodologies for stability and for predicting compatibility, as well as their applicability and correct interpretation.

CIMAC is a project sponsor of the Joint Industry Guidance on the supply and use of 0.50% – sulphur marine fuel which was released in August 2019. The new CIMAC guideline builds on the Joint Industry Guidance and provides practical and detailed advice on fuel handling that should be required reading for those responsible for procurement of bunkers and fuel management onboard for vessels using residual fuels.

Stability vs compatibility

Residual fuel oils contain asphaltenes which is a generic term covering a wide range of heavier hydrocarbon structures of high molecular weight and high carbon/hydrogen ratios. If the asphaltenes cannot be retained in their suspended state, they will drop out as sludge and the fuel becomes unstable – also called ‘asphaltene precipitation’. The sludge is difficult to remove and in the worst case can harden into “coke like material” that must be removed manually.

The stability of a residual fuel is defined by its resistance to precipitate asphaltenic sludge despite being subjected to forces, such as thermal and ageing stresses, while handled and stored under normal operating conditions.

While stability is a characteristic of a single fuel as supplied, compatibility is the ability of two or more fuels to be comingled without evidence of material separation; or in other words, no asphaltenes precipitating when the fuels are mixed. Two perfectly stable fuels may be incompatible when mixed. Two stable fuels that are compatible at some mixing ratios may also be incompatible at other mixing ratios. It is therefore critical to properly test for compatibility before commingling.

From a ship perspective, the impact of an unstable fuel is identical to the impact of having mixed two incompatible fuels. In both instances, excessive sludge concentration may form in tanks and can readily choke purifiers, filters, fuel injection equipment and even fuel lines themselves. However, the responsibilities are very different. “It is the responsibility of the supplier to provide a stable product whereas it is the responsibility of the engineers on board to apply best fuel management practice to mitigate the risk associated with mixing incompatible fuels” states CIMAC. 

Key recommendations

In order to mitigate the risk of a fuel becoming unstable on board, CIMAC recommends all marine fuels be purchased under ISO 8217:2017, including the information given in the ISO/PAS 23263:2019. Furthermore, ships’ crews are advised to apply a “first-in first-out” fuel inventory principle and make every effort to prevent the fuel being unnecessarily heated over extended periods.

Commingling of bunker fuel is never recommended but if there is no other option than to load on top in the bunker tank, CIMAC recommends that compatibility checks are made using actual ratios or if not known then ratios of around 10/90, 50/50 and 90/10 are recommended as a minimum. CIMAC also emphasizes on controlled laboratory testing for determining stability or compatibility.

The guideline in its entirety is available on the CIMAC website.

Further reading

Reference is also made to our publications Marine fuel – a toxic mix? and Contaminated bunkers: protecting the purchaser, highlighting some learning points from the “Houston contaminated bunker” cases in 2018. Our Alert Is the fuel in your emergency equipment fit for the purpose? emphasizes the importance of ensuring quality fuel being used for emergency equipment.

Source and photo credit: Gard
Published: 2 November, 2019

 

Continue Reading

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.

Admin

Published

on

By

india flag

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

Continue Reading

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.

Admin

Published

on

By

shraga kopstein on Unsplash

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

Continue Reading

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.

Admin

Published

on

By

Sheen Mao MT

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

Continue Reading

Trending