Bunker Fuel
VPS discusses mitigating risks in sustainable vessel operations with its APS
Harun Rashid, Senior Technical Manager of VPS explains how to safeguard vessels against bunker fuel instability with VPS Additional Protection Service.
Harun Rashid, Senior Technical Manager of marine fuels testing company VPS on Tuesday (19 March) published an article on how to safeguard vessels against marine fuel instability with VPS Additional Protection Service (APS):
Stability has long been a highly unpredictable character of marine fuels, which is extremely sensitive to a fuel’s formulation and its storage and handling conditions. For these reasons, fuel buyers have no direct control on fuel stability, unlike other physical parameters, other than relying upon a supplier’s due diligence regarding the fuel formulation and the ship’s engineer’s professionalism in managing the fuel on board.
Asphaltenes within residual-based fuels can precipitate as sediment/sludge whenever a fuel’s available solvency to retain asphaltenes in suspension drops below the fuel’s stability reserve. The ISO 8217:2012/17 standard has a sediment limit of a maximum 0.10% m/m to protect buyers’ interest where an elevated sediment value can be indicative of an unstable fuel. Today’s fuels are no longer produced from straight run refining processes, but undergo a series of complex processes, for example, vacuum distillation, vis-breaking, catalytic cracking, in order to extract the lighter end components as much as possible, leaving the bottom end components with reduced reserve stability. The solvency can further diminish with unregulated blending in order to meet the Sulphur compliance levels within MARPOL Annex VI & statutory regulations.
During 2023, VPS handled numerous sludge formation cases which led to severe filter & separator blockages. The majority of these cases involved VLSFO fuels and for a sizeable number, the sediment content at the ship’s manifold was actually below the 0.10%m/m specification limit. In one case, a ship received a VLSFO in an Asian port with sediment content 0.07%m/m and reported severe sludge formation soon after the fuel was put into use, with sludge formation continuing throughout the use of the fuel.
The sludge formation was so severe that the engineers had to clean the purifier bowl assembly every 4 hours, compared to a usual cleaning interval of 250 hours. At one point, the engineers discontinued using the fuel, as the vessel ran out of spare parts. Analysis of system samples later confirmed that the sludge formation was indeed due to unstable fuel and not from on-board mixing.
While the number of sludge formation cases clearly singles out VLSFO as more unstable and challenging to manage on-board, compared to HSFOs, another challenge is to prevent wax formation without exposing fuel to excessive heat and accelerated fuel ageing. With VLSFOs being more parafinnic in nature, a good number may require heating beyond their pour point to prevent wax formation.
VPS 2023 data shows, at least 15.8% of VLSFO samples had a wax appearance temp (WAT) above 40C, including 1.6% above 50C. These samples will precipitate wax if storage temps are not kept above the WAT, compared to the lower storage temperature requirements based on their tested pour points.
Wax formation is a reversible process, so theoretically, it should not cause any operational issue as long as fuel remains stable, but unfortunately, fuel stability is not guaranteed. Moreover, if wax is allowed to form, wax and aspheltenes (sludge) can co-mingle together as a result, the wax disappearance temperature may increase significantly and in the worst case, the wax may no longer disappear.
Taking a middle approach and striking a balance could be one option where the fuel is not severely overheated, nor the wax allowed to form freely during storage and only increase temperatures during transfer if needed. VLSFO with such high WAT/WDT will need close attention and care during storage, transfer, treatment and use. Prolonged storage should also be avoided for such fuels.
Sludge formation on the other hand is an irreversible process, meaning it is not possible to convert the precipitated sludge back into the fuel. As there is no quick fix, efficient handling of fuel treatment plants becomes so critical otherwise, severe clogging of filters and separators can lead to fuel starvation to the engine and a loss of propulsion placing greater risk to the safety of the crew, ship, and the environment.
Avoiding a catastrophic situation requires visiting the entire fuel management chain and adhering to best practices. It starts with buying fuel from trusted suppliers, followed by verifying the fuel quality in one of the VPS, ISO17025 accredited laboratories.
VPS offers an Additional Protection Service (APS) package which includes a stability assessment of the fuel.
VPS additional protection service (APS) package
Parameters such as Separability Number (Reserve Stability Number) and Total Sediment Existent (TSE) together with Total Sediment Potential (TSP) results provides an excellent indication of fuel stability while GC/MS screening and follow up testing ensures the fuel is not contaminated with harmful chemical species at levels considered “unfit for use”. Testing Wax appearance & disappearance temperatures assist in maintaining optimal heating to prevent wax formation whilst also avoiding overheating and fuel ageing.
If a vessel uses stability additives, then its performance evaluation should not only be in assessing the improvement of the reserve stability number, but to conduct a broader assessment across fleet including assessing sediment reduction. Crew training is key, as poor handling of fuel by incompetent crew can also trigger a sludge formation situation.
A deeper understanding of the fuel’s quality can be achieved, coupled with a further reduction of any associated risk, by going beyond ISO 8217 and using the APS test scope. This service will ultimately save time, money and company reputation.
Photo credit: VPS
Published: 20 March 2024
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Bunker Fuel Availability
JLC China Bunker Fuel Market Monthly Report (June 2025)
Country sold about 1.74 million mt of bonded bunker fuel in June, with the daily sales at 57,910 mt, a dip of 0.26% month on month, JLC’s data shows.
Beijing-based commodity market information provider JLC Network Technology Co. recently shared its JLC China Bunker monthly report for June 2025 with Manifold Times through an exclusive arrangement:
Bunker Fuel Demand
China’s bonded bunker fuel sales inch lower in June
China’s bonded bunker fuel sales inched lower in June, due to the negative impact from geopolitical tensions and seasonally tepid shipping demand.
The country sold about 1.74 million mt of bonded bunker fuel in June, with the daily sales at 57,910 mt, a dip of 0.26% month on month, JLC’s data shows.
Bonded bunker fuel sales by Chimbusco, Sinopec (Zhoushan), SinoBunker and China Changjiang Bunker (Sinopec) respectively settled at 460,000 mt, 560,000 mt, 45,000 mt and 25,000 mt in the month, while those by suppliers with regional bunkering licenses stood at 647,300 mt.
The efficiency of global trade declined amid trade war, leading to a slip in the world’s bunkering demand.
China’s LSFO output rallies in June
China’s LSFO output rallied in June amid unit restarts, but the rally was limited to some degree by some refineries’ maintenance and bad production margins.
Chinese refiners produced about 1.02 million mt of LSFO in the month, with the daily output rising by 10.58% month on month to 34,067 mt, JLC’s data shows.
Specifically, Sinopec maintained basically stable LSFO production in June. The company’s Shengli Oilfield and Jinling Petrochemical slashed their production after launching maintenance in the middle of the month, while Shanghai Gaoqiao Petrochemical, Hunan Petrochemical and Tianjin Petrochemical wrapped up turnarounds and boosted their output.
PetroChina recorded a modest rise in its production in June as Jinxi Petrochemical restarted its units. However, Jinzhou Petrochemical and Liaohe Petrochemical slightly cut their production. The output of other refineries did not change much in the month.
CNOOC saw a significant boost in its output in the month, as Huizhou Refinery resumed production while Zhoushan Petrochemical and Taizhou Petrochemical ramped up production.
ZPC and Sinochem did not produce any LSFO in June, but the latter exported 10,000 mt of MGO.
On a year-on-year comparison, however, China’s LSFO output fell by 22.75% in June.
Domestic-trade bunker fuel demand weakens in June
Domestic-trade bunker fuel demand further weakened in June, with most shipowners still holding a wait-and-see attitude.
Domestic-trade heavy bunker fuel demand slipped to 340,000 mt in the month, down 20,000 mt or 5.56% from the previous month, JLC’s data shows. Most purchases were still based on rigid demand, though market sentiment became slightly bullish.
Meanwhile, domestic-trade light bunker fuel demand declined to 140,000 mt, down 10,000 mt or 6.67% month on month. Diesel demand remained lackluster amid the fishing moratorium.
Bunker Fuel Supply
China’s bonded bunker fuel imports rebound in May
China’s bonded bunker fuel imports rebounded in May, as domestic refiners increased purchases of imported LSFO when domestic supply tightened.
Chinese bunker suppliers imported 610,500 mt of bonded bunker fuel in the month, a boost of 16.17% month on month and 97.06% year on year, JLC’s calculation shows, based on data from the GACC.
Domestic LSFO output extended declines amid more unit maintenance, forcing bonded distributors to place more orders for imported LSFO. Meanwhile, HSFO imports increased amid growing demand, while MGO arrivals dropped amid larger domestic production and tepid demand.
Russia became the largest bonded bunker fuel supplier to China in May, up from the fourth place in April. The country exported 377,700 mt of bonded bunker fuel to China in the month, accounting for 61.88% of the latter’s total imports. At the same time, Singapore came second with 144,500 mt, accounting for 23.67%, while South Korea ranked third with 50,300 mt, accounting for 8.23%. In addition, Malaysia ranked fourth with 38,000 mt, occupying 6.22%.
China’s bonded bunker fuel imports totaled 2.66 million mt in January-May, surging by 64.54% year on year, the calculation shows.
Domestic-trade bunker fuel supply continues to tighten in June
Domestic-trade bunker fuel supply continued to tighten in June, as the availability of blendstock declined and most blending in northeast and east China was still at a halt.
Blenders supplied about 360,000 mt of domestic-trade heavy bunker fuel in the month, down by 10,000 mt or 2.70% month on month, JLC’s data shows.
Domestic supply of low-sulfur residual oil tightened as China Offshore Bitumen (Binzhou) came under maintenance, while that of shale oil also declined. Meanwhile, most blenders in northeast and eastern China were yet to resume their blending, as the impact of tax inspections persisted.
Domestic-trade light bunker fuel supply dropped to 150,000 mt in June, down by 10,000 mt or 6.25% month on month, the data shows. Diesel supply tightened as some refineries lowered their operating rates amid unit maintenance.
Bunker Prices, Profits
Editor
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JLC Network Technology Co., Ltd is recognised as the leading information provider in China. We specialise in providing the transparent, high-value, authoritative market intelligence and professional analysis in commodity market. Our expertise covers oil, gas, coal, chemical, plastic, rubber, fertilizer and metal industry, etc.
JLC China Bunker Fuel Market Monthly Report is published by JLC Network Technology Co., Ltd every month on China bunker market, demand, supply, margin, freight index, forecast and so on. The report provides full-scale & concise insight into China bunker oil market.
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Related: JLC China Bunker Fuel Market Monthly Report (May 2025)
Related: [Updated 15 May] JLC China Bunker Market Monthly Report (April 2025)
Related: JLC China Bunker Market Monthly Report (February 2025)
Related: JLC China Bunker Fuel Market Monthly Report (January 2025)
Related: JLC China Bunker Fuel Market Monthly Report (December 2024)
Related: JLC China Bunker Fuel Market Monthly Report (November 2024)
Related: JLC China Bunker Fuel Market Monthly Report (October 2024)
Related: JLC China Bunker Fuel Market Monthly Report (September 2024)
Related: JLC China Bunker Fuel Market Monthly Report (August 2024)
Related: JLC China Bunker Fuel Market Monthly Report (July 2024)
Related: JLC China Bunker Fuel Market Monthly Report (June 2024)
Related: JLC China Bunker Fuel Market Monthly Report (May 2024)
Related: JLC China Bunker Market Monthly Report (April 2024)
Related: JLC China Bunker Market Monthly Report (March 2024)
Related: JLC China Bunker Fuel Market Monthly Report (February 2024)
Related: JLC China Bunker Market Monthly Report (January 2024)
Note: China-based commodity market information provider JLC Technology has been providing Singapore bunkering publication Manifold Times China bunker volume data since 2020. Data from earlier periods are available here.
Photo credit: JLC Network Technology
Published: 10 July 2025
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