ISO and CIMAC to publish guidance on 0.50% sulphur fuels

Paul Gunton
Paul Gunton
ShipInsight

03 June 2019


Guidance on how to manage the low sulphur fuels that will come into use from 1 January 2020 is expected to be published in August or September by both the International Organization for Standardization (ISO) and the International Council on Combustion Engines (known by its French abbreviation, CIMAC).

In an interview with ShipInsight, the convenor of the ISO Classification and Specification of Marine Fuels Working Group Monique Vermeire said that the organisation plans to publish a Publicly Available Specification (PAS) that will address “specific considerations that may apply to some of the 0.50% fuels.”

MV_Prinsendam_R01

Meanwhile, CIMAC – for which she is a member of its Fuels Working Group – is preparing some guidance on fuel stability and compatibility that will be relevant to all fuel grades. It will also describe tests that can be used to check stability and compatibility and the limitations of those tests, she said.

The CIMAC working group’s web pages confirm that one of its aims is to “support the ISO 8217 Fuel Standard Group” whose progress with this PAS can be followed online on the ISO website. Ms Vermeire told IMO’s Marine Environment Protection Committee (MEPC 74) on 13 May that a two-month commenting period about the PAS had opened on 18 April, after which those comments will be reviewed before the specification is published.

She also explained to MEPC 74 why a PAS was being developed, rather than revising ISO 8217, which was last updated in 2017. Its work had been prompted by a request by MEPC 71 in July 2017 that ISO consider the framework of its fuel standard with a view to ensuring consistency between ISO standards on marine fuel oils and the 0.50% sulphur limit. That meeting had set MEPC 74 as a deadline for a response and Ms Vermeire told the committee that, because of the implementation date and because 0.50% sulphur fuels were not widely available at the time, it was not possible to revise the standard in the time available. “Therefore ISO initiated the process to develop an ISO PAS.”

She provided more detail to ShipInsight, saying that the lack of suitable fuels meant that there was not enough industry experience to draw on to justify amending the standard, which is something that normally takes between three and five years to assess. So the PAS will provide an interim alternative that can remain in effect for an initial three years, which can be extended for another three years if necessary.

Although there was a shortage of service experience, the ISO working group was provided with samples for testing in early 2018 but she pointed out that this was nearly two years before the sulphur cap comes into effect so some of them may have been prototypes and not their suppliers’ final blends.

Speaking to MEPC, she said that these samples had been tested “to address the potential risk of incompatibility when commingling fuels having varying blend formulations” and to investigate whether “test methods currently not yet widely used for marine fuel stability testing” can provide information on the stability and potential instability of fuels or mixtures of fuels.

Although the test methods might be new to the marine sector, they are already used in refineries to check parameters that relate to the stability of the asphaltenes in the fuels and the ability of the fuel oil matrix to keep the asphaltenes in solution.

Tests were done on samples of fuels including ULSFO, VLSFO and HSFO (the PAS will not cover gas fuels, such as LNG) and “predicted that approximately 50% of the evaluated mixtures show the fuels, despite their diverse formulations, to be compatible whatever the mixing ratio is, with a total sediment potential (TSP) below 0.10%,” she told MEPC 74. For the remaining 50%, the tests indicated “a risk for incompatibility at specific mixing ratio[s], but often not confirmed by elevated TSP test results.” More detail will be given in the study’s final report, she told delegates.

Speaking to ShipInsight, Ms Vermeire said that the PAS will address fuel commingling and compatibility from a general point of view and will include an informative annex on commingling of fuels. The CIMAC document will include more detail about fuel stability and compatibility and the test methods that can be applied.

Fuel compatibility post-2020 is a topic that is often raised as a potential concern and Ms Vermeire referred ShipInsight to guidance issued by IMO after MEPC 73 in October last year aimed at fuel suppliers to assure the quality of their delivered fuel. Among other things, it requires suppliers to provide information on “any known compatibility issues particular to the product”.

She also pointed out that compatibility problems are not new and that these can be addressed by keeping different fuels apart and by maintaining good bunker management. Although there may be more instances of incompatible fuels post-2020, she recommended that existing segregation regimes should be used for 0.50% sulphur fuels. For ships that do not currently manage their fuels in that way, there may be some additional complications as they begin to handle these new fuels, she said.

She suggested that, to reduce compatibility problems, it is important to minimise the amount of fuel in a tank and to know how much fuel is left in it before bunkering new fuel into it. This is no different from current practice, she suggested, and noted that ships trading into ECAs have already gained relevant experience of switching between segregated fuels.

Despite the potential differences between low- and high-sulphur fuels, ISO 8217 is valid for both, she stressed, but said that the PAS will advise bunker buyers and fuel users to be alert to their different properties such as viscosities and cold flow properties. For example, if an order is placed for a 380cSt HFO, the delivered fuel will not be far from that figure. A 380cSt low-sulphur fuel, however, could be very different from that on delivery, perhaps 220cSt she suggested, depending on the blend’s composition.

A ship’s automatic viscometers and heating equipment will adjust to that, she said, but nonetheless, “communication between the supplier and the purchaser will probably become more important after 0.50% sulphur fuel appears.”