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While 2020 was predicted to be a seismic year for the marine fuels industry, the coronavirus pandemic further intensified the pressures of complying with IMO 2020. At ARACON a panel of fuel testers gave their assessment of the sector’s transition to very low sulphur fuel oil (VLSFO).

Opening proceedings, Muhammad Usman, Product Manager, Lloyd’s Register FOBAS, struck an optimistic tone, noting that there are ‘positive signs’ that ships are getting more adjusted to the new fuels, but cautioned, ‘we need to remain alert as these fuels can spring a surprise at any time.’

Off specification levels had remained ‘steady’ on a month-by-month basis throughout the year, said Usman. More specifically, of all off-spec fuels detected by FOBAS, total sediment accounted for more than half (51%). Other significant issues were sulphur (27%) and water (11%).

Looking ahead, Usman set out guidance for ship operators when using new VLSFOs.

‘We need to follow best practice [and] seek improvements through employing machinery conditioning monitoring. [We] also need to keep the records up-to-date and the lines of communication open to share experience so that we can learn from each other and we can move the industry forward.’

Gunnar Kjeldsen, Global Business Development Manager, Bureau Veritas VeriFuel, then summarised some of the fuel testing agency’s findings from the ARA region since the turn of the year.

Of the major bunker hub ports around the world, ARA ports, said Kjeldsen, had the highest percentage of out of spec fuel samples for VLSFO. Some 6.5% of all VLSFO fuels tested by VeriFuel in the ARA were found to be out of spec of which 42% were due to sediment.

‘This is a much higher percentage than we have seen before with fuel oils and if the sediment is due to the fuel being unstable, it will be difficult – to almost impossible – to handle onboard if the sediment levels are high,’ said Kjeldsen.

He then went on to break down the off-spec cases of VLSFO in the ARA on a month-by-month basis, noting that industry ‘did expect some teething issues in the beginning but it seems that the worst months were April and May.’ In contrast, October was found to be the month with the fewest problems.

Kjeldsen then highlighted the ‘clear trend’ when examining the relationship between average viscosity and average sediment.

‘The lower the viscosity, the higher the sediment content. If viscosity falls below 30 centistokes (cSt) at 50 °C, there is a 12% chance that the sediment test will be higher than the 0.10% limit,’ said Kjeldsen. ‘VeriFuel has not seen one sample exceeding the sediment limit when the viscosity was over 150 cSt in ARA.’

While the average viscosity of VLSFO in the ARA during the first 10 months of 2020 was 68 cSt, Kjeldsen highlighted the ‘huge’ variation, from as low as 7 cSt to as high as 474 cSt, between suppliers.

‘It is important for the ship operator to know about viscosity since it impacts both the efficiency of the fuel treatment and separators onboard, and the injection viscosity. Viscosity is highly temperature dependent.’

Kjeldsen added: ‘By controlling the temperature onboard, it is possible to ensure that everything is working optimally. It is however important to know the actual viscosity of the fuels supplied in order to ensure that temperature is controlled from tank storage over separation to the fuel injection.’

Veritas Petroleum Services’ (VPS) Group Commercial Director, Steve Bee, said the stability of VLSFOs ‘has always been an area requiring additional concentration’.

He said: ‘The fact that many VLSFOs are highly blended fuels with a varying mix of aromatic paraffinic components leads to a greater potential for the fuel to destabilise forming asphaltene sludges, waxes or both.’

Bee then went through some of the issues related to VLSFOs that VPS had encountered during September. These included Total Sediment Potential (TSP), which accounted for 3.6% of off-spec VLSFO during the month, though Bee noted that VPS had witnessed ‘many stability issues’ without the TSP being off-specification.

‘Where VLSFOs have been tested as stable and bunkered, some within only a few weeks have become unstable indicating their storage lifespan is much shorter than the more traditional marine fuels,’ said Bee. ‘The average shelf life of a VLSFO is less than three months compared to an HSFO [high sulphur fuel oil] of six months and an MGO [marine gasoil] of 12 months.’

Bee also noted that since the introduction of VLSFOs, the fuels had exhibited higher catfines levels than heavy fuel oils, though this was now starting to level out.

‘In January, 22% of samples showed a catfine level of greater than 40 PPM [parts per million]. However, more recently, VLSFO catfine levels have reduced quite significantly across all major bunker regions and we now see only 11% of samples with catfines greater than 40 PPM. And only 0.5% of samples tested are greater than the 60 PPM limit.’

Like Kjeldsen before him, Bee also highlighted the ‘wide and variable’ range in viscosity for VLSFOs. A problem at the start of the year, Bee said this is remains the case today.

‘This is still the situation, with a viscosity range going from 2 cSt to 590 cSt in September – having said this, the majority of VLSFOs fall between 20 cSt and 110 cSt,’ said Bee. ‘This is still a fair way off the 380 cSt which shipping was used to pre-IMO 2020.’

Bee noted that currently 95% of VLSFOs tested had shown a viscosity of less than 280 cSt and 86% a viscosity of less than 180 cSt.

Bee said that during the first quarter of 2020, VPS had identified ‘significant’ engine damage - in the form of hard, abrasive deposits on piston crowns, excessive cylinder liner wear and broken piston rings - arising in more than 40 vessels. As a consequence of this damage, VPS undertook a comprehensive investigation.

‘The investigation identified the reserve base number in the cylinder oil was not being utilised to neutralise the acids formed during the fuel combustion process as is its purpose,’ said Bee. ‘This resulted in calcium compounds being deposited on the piston crown, which became hard and abrasive, causing liner wear, liner scuffing and piston ring breakage, resulting in serious operational issues.’

Bee continued: ‘It is worth noting, in general, when the base number is reduced, the lubricating oil detergency reduces and the oil film is lost; but when the base number increases, the detergency improves and the oil film is detained – but then, calcium deposit formation may start.’

Bee the set out several preventative actions that could be taken by ship operators using VLSFOs to protect the engines and avoid operational issues arising from excessive liner wear.

‘Primarily, undertaking cylinder scrape down analysis will identify if an adequate lubricating oil formation is being used which may be further confirmed by a sweep test,’ said Bee. ‘In addition to this, the ship operator should closely monitor engine operation during an introduction of new VLSFO fuel and changeover of VLSFOs to MGO or MGO to VLSFO when entering or leaving an ECA [emission control area].’

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