Business

VPS: Why correct temperature management of VLSFO bunker fuel is required to protect your assets

VPS explains how understanding WAT and finding the balance between fuel temperature and viscosity can make all the difference in ensuring asset protection and the smooth operation of vessels.

Published

3 years ago

September 6, 2023

Admin

Wolf Rehder, Area Manager Germany of marine fuels testing company VPS, on Tuesday (5 September) delved into the importance of proper VLSFO fuel management as VLSFOs come with unique challenges, including fuel destabilisation and the dreaded wax formation.

He explained how the Wax Appearance Temperature (WAT) and finding that delicate balance between fuel temperature and viscosity can make all the difference in ensuring asset protection and the smooth operation of vessels:

With the introduction of the IMO sulphur cap as of 1 January 2020, correct fuel management increased in importance. One of the challenges faced on-board is finding the optimal fuel temperature throughout the fuel system.

We have seen that Very Low Sulphur Fuel Oil (VLSFO) can quickly destabilise once on-board the ship, with some of these fuels having a shelf life of less than three months. This process of destabilisation accelerates when the fuel is heated. As a result, excessive sludging can be experienced, leading to issues such as clogging filters and separators.

VLSFOs are by nature, more paraffinic than “conventional” High Sulphur Fuel Oils. Should the fuel not be kept at a sufficient temperature, then wax formation maybe the resulting outcome, affecting separators operation, as well as clogging fuel systems including filters. The historical advice of storing fuels at 10°C above the pour point can sometimes be misleading with regard to VLSFOs, as wax formation may start at temperatures higher than the pour point. VPS global statistics on Very Low Sulphur Fuel Oil indicates that Wax Appearance Temperature (WAT) is about 20°C above Pour Point.

Maintaining settling tank temperatures below the WAT can lead to wax precipitation in the tanks which could then block the suction line and could also reduce the heating efficiency if the wax covers the heating coils. Therefore, knowing the exact WAT is essential to ensure correct fuel management.

WAT test method that was introduced by VPS in 2019, has helped numerous ship owners and operators to overcome this problem.

Keep fuel temperature as low as possible – but as high as necessary

Fuel temperature must be managed on a case-by-case basis and is a fine balance between the viscosity and WAT. Heating the fuel in the storage tanks for an extended period is not recommended as it would significantly deteriorate the condition of the fuel and fasten the ageing process.

However, heating the fuel to achieve the appropriate purification temperature and injection viscosity cannot be avoided, since this is for a relatively short period assuming the fuel leaving the purifier is immediately consumed, the damage is limited.

In the past a separation temperature of 98°C was carved in stone. With the onset of VLSFOs since 2020, we have seen a significant reduction in viscosity which means lower separating temperatures at the purifiers.

Temperatures along the fuel system

As shown in the above figure 1, we can see the separator manufacturers generally recommend the storage and separation temperatures based on the viscosity of the fuel. Where the recommended separation temperature is below the WAT, this results in separator sludging or complete blockage in the worst case.

This problem can be more severe in cases where cat-fines are high and viscosity is low. The problem of heating a low viscosity fuel above the WAT, is that the viscosity becomes so low that the fuel booster pumps of the vessel cannot produce sufficient pressure, introducing leakages and can potentially leading to vapour lock. When a vessel cannot increase the temperature above the WAT, due to operational restrictions, the fuel is essentially unusable. For this reason understanding the correct WAT is critical when using VLSFO.

Photo credit: VPS
Published: 6 September, 2023

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Singapore withdraws remaining 127 charges against Hin Leong founder OK Lim

Lim Oon Kuin, also known as OK Lim, was issued a stern warning and a district court granted him a discharge amounting to an acquittal for these charges on 17 July.

Published

16 hours ago

July 21, 2026

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Founder of collapsed oil trader Hin Leong Trading, Lim Oon Kuin, also known as OK Lim, has had the remaining 127 charges against him withdrawn, according to The Straits Times on Monday (20 July).

OK Lim was issued a stern warning and a district court granted him a discharge amounting to an acquittal for these charges, including those for cheating, on 17 July. The discharge means Lim cannot be prosecuted again for the same offences.

Lim, 84, is currently serving a 13½-year prison sentence after the High Court reduced his original 17½-year jail term in March 2026. He was convicted in 2024 on two cheating charges and one count of abetting forgery in a case prosecutors described as one of Singapore’s most serious trade finance frauds.

Lim was convicted in May 2024 of two charges of cheating the Hongkong and Shanghai Banking Corporation (HSBC) and one count of abetting forgery that proceeded to trial out of a total of 130 criminal charges.

He was first charged in court on 14 August 2020, and was subsequently handed further charges in court on 25 September 2020, 30 April 2021 and 24 June 2021 for his role in perpetuating fraud on various financial institutions.

A total of 130 charges were eventually brought against him for cheating and forgery-related offences.

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Published: 21 July, 2026

Winding up

Singapore: Coastal Logistics Pte Ltd to be wound up voluntarily

Coastal Logistics was reportedly affiliated with troubled Singapore bunker player Coastal Oil (Singapore) Pte Ltd.

Published

16 hours ago

July 21, 2026

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Several resolutions for Coastal Logistics Pte Ltd were made during an extraordinary general meeting held on 14 July, according to a notice in the Government Gazette on Friday (4 July).

The following resolutions were duly passed during the meeting:

As Special Resolution

That it has been proved to the satisfaction of the meeting that the Company cannot by reason of its liabilities continue its business and accordingly the Company be wound up voluntarily pursuant to Section 160(1)(b) of the Insolvency, Restructuring and Dissolution Act 2018 (No. 40 of 2018);

As Ordinary Resolutions

that Mr. Wong Pheng Cheong Martin and Ms. Koay May Yee, both care of FTI Consulting (Singapore) Pte Ltd, One Raffles Quay, #27-10 South Tower, Singapore 048583 be appointed as the joint and several Liquidators of the Company for the purpose of such winding up; and
that the Liquidators be at liberty to open, maintain and operate any bank account(s) or account(s) for monies received by them as Liquidators with such bank(s) as they deem fit; and
that a Committee of Inspection will not be formed.

Manifold Times previously reported Nicholas James Gronow, director of Heng Tong Fuels & Shipping and Coastal Logistics, filed statutory declarations for both companies stating the firms cannot continue their businesses due to liabilities.

Both companies were reportedly affiliated with troubled Singapore bunker player Coastal Oil (Singapore) Pte Ltd.

In 2019, several vessels owned by both firms entered the sale & purchase (S&P) market in Singapore.

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Published: 21 July, 2026

LNG Bunkering

PIL’s LNG dual-fuel boxship “Kota Elok” arrives in Singapore on maiden call

As the first of 13 new 13,000 TEU vessels joining its fleet, Kota Elok is equipped to operate on LNG and low-sulphur fuel oil that helps reduce our greenhouse gas emissions.

Published

16 hours ago

July 21, 2026

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PIL's LNG dual-fuel boxship “Kota Elok” arrives in Singapore on maiden call

Singapore-based Pacific International Lines Pte Ltd on Monday (20 July) said its first 13,000 TEU LNG dual-fuel container vessel, Kota Elok, recently made her maiden call to Singapore on 15 July.

As the first of 13 new 13,000 TEU vessels joining its fleet, Kota Elok is equipped to operate on liquefied natural gas (LNG) and low-sulphur fuel oil that helps reduce our greenhouse gas emissions.

The vessel also incorporated energy-saving features and digital technologies to reduce fuel consumption and enhance operational performance, as well as a bow windshield to improve aerodynamics, contributing to improved fuel efficiency and lower emissions over the course of long-haul voyages.

“Following Singapore, Kota Elok will continue her voyage on our East Coast Service 1 (ES1) route to South America, calling at ports in Brazil, Uruguay, and Argentina before returning to Asia,” the company said in a social media post.

Kota Elok also became PIL’s first vessel to receive Lloyd’s Register certification for compliance with the IACS UR E26 and UR E27 cyber security requirements.

Developed by the International Association of Classification Societies (IACS), UR E26 and UR E27 are mandatory cyber resilience requirements for newbuild vessels contracted from 1 July 2024.

Photo credit: Pacific International Lines
Published: 21 July, 2026