Since 2016 and the IMO’s decision to cut the permitted sulphur level in fuels used outside of ECAs to 0.5%, debate has raged over how ships can best comply with the requirement. The cut is of course a MARPOL rather than a SOLAS matter and emissions and fuel choices are rightfully covered under the MARPOL convention.
However, many have argued that there is also a safety aspect to the new rules that has been mostly overlooked in the scrubber v LNG v new fuels debate. The safety issue is not merely a repeat of what took place when the permitted sulphur limits in ECAs were reduced some years ago, although it has to be said that the same concerns that arose them will come into play on a much wider scale. Ships calling regularly to the four existing ECAs or to EU ports have by and large learned how to manage changeovers but this will be new ground for many ships’ crews around the globe when the new rules come into effect on 1 January 2020.
With so many new compliant fuels promised to be introduced in time for the new rules, concerns over compatibility and miscibility of the fuels have been raised. Thus many believe there is a high risk of ships suddenly losing power or suffering engine damage, fires and explosions under certain circumstances.
At MSC 100, it was agreed for the committee to include in its agenda for MSC 101 a new item on “Development of further measures to enhance the safety of ships relating to the use of fuel oil”. This followed the consideration of submissions concerning the potential need for guidance and advice concerning possible safety issues related to the implementation of the 0.50% limit of the sulphur content of fuel oil outside emission control areas. At the same time, the committee endorsed the view that, while fuel safety was a longstanding existing concern which needed to be carefully addressed, this should not affect Member States’ commitment to implementing the 2020 sulphur limit from the date of application.
Member States and international organisations were invited to submit concrete proposals to MSC 101 in June 2019 under the new output. The scope of work was agreed as follows: “Based on the review of existing safety provisions for fuel oil and information concerning the safety implications associated with the use of fuel oil, develop further measures to enhance the safety of ships relating to the use of fuel oil.” The target completion date is 2021.
The Marine Environment Protection Committee (MEPC 73) in October 2018 invited the MSC to consider relevant safety issues associated with the use of low-sulphur fuel oil, following the Intersessional Working Group on Consistent implementation of regulation 14.1.3 of MARPOL Annex VI (ISWG-AP 1).
The MSC agreed that a joint MSC-MEPC circular on ensuring fuel suppliers deliver compliant fuels should be developed by the Sub-Committee on Pollution Prevention and Response (PPR 6) held in February 2019, with a view to approval by MEPC 74 and MSC 101. MSC also noted the initiative of industry organisations to develop guidance to address potential safety and operational issues related to the supply and use of 0.50% sulphur fuels.
The potential problems were identified as:
- Stability – Very Low Sulphur Fuel Oil, which does not have the same stabilising effect as aromatic components in current fuels, can cause sludge build-up and blockage of centrifuges and filters due to the existence of paraffinic (wax) components.
- Compatibility Issues – segregation of Very Low Sulphur Fuel Oil (paraffinic-based versus aromatic-based) to facilitate proper management and handling.
- Cold Flow Properties – proper temperature management is needed to mitigate wax crystal formation at temperatures below the pour point when operating in colder regions which can lead to blockages at the filters and reduced fuel flow to the machinery plants.
- Acid Number – fuels with high acid number test results cause accelerated damage to marine diesel engines. However, there is no recognised correlation between an acid number test result and corrosive activity of the fuel.
- Flashpoint – the expectation that distillates will be supplied with flashpoints less than the 60°C SOLAS requirement not only presents an increased risk of fire and explosion, but violates SOLAS.
- Ignition and combustion characteristics – operational problems, engine damage and even total engine breakdown can occur when using fuels with poor ignition and combustion properties.
- Cat fines – abrasive wear of cylinder liners, piston rings and fuel injection equipment can occur if not sufficiently reduced by fuel treatment systems.
- Low-viscosity distillate – this is highly temperature-dependent and requires proper temperature management to avoid viscosity less than 2cSt, which can challenge the performance of the fuel pumps.
- Fuel Blending – clear cause and effect between blend components and associated operational problems is limited and there is a lack of statistical studies available to know which components are typically found in fuels and at what concentration.
As well as looking at the issues around new fuels, MSC 100 also approved revisions to the IGF Code which governs the use of gas and low-flashpoint fuels. The revisions apply to ships of 500gt and above and all passenger vessels using low-flashpoint fuels. The revisions will likely be adopted at MSC 101 and that it will assign the following dates to define new ships:
- a building contract placed on or after 1 January 2021; or
- in the absence of a building contract, the keel of which is laid or which is at a similar stage of construction on or after 1 July 2021; and
- regardless of the building contract or keel laying date, the delivery is on or after 1 January 2025.
The revisions include the following provisions:
- Where cargo tank insulation and location make the probability for the tank contents to be heated up due to an external fire very small, higher loading limits than calculated using the reference temperature may be permitted, but not more than 95%.
- Gaseous fuel pipes, except fully welded fuel gas vent pipes led through mechanically ventilated spaces, which pass through enclosed spaces, except piping in fuel preparation rooms or spaces surrounding all tank connections and valves, shall be protected by a secondary enclosure which may be a ventilated duct or a double-wall piping system.
- Exhaust systems of internal combustion engines of piston type shall be equipped with explosion relief systems unless designed to accommodate the worst case overpressure due to ignited gas leaks or justified by the safety concept for the engine.
- Crediting the use of fuel storage hold spaces as a cofferdam for type C tanks that are not located directly above category A machinery spaces or other rooms with high fire risk.
In another fuel-related measure, MSC 100 instructed its relevant sub-committees to consider parts of the draft interim guidelines for the safety of ships using methyl/ethyl alcohol as fuel prepared by CCC 5. The detailed interim guidelines provide requirements for the arrangement, installation, control and monitoring of machinery, equipment and systems using these types of fuel to minimise the risk to the ship, its crew and the environment, taking into account to the nature of the fuels involved.