Big questions still hang over the safety of new low-sulphur fuels to be introduced on 1 January 2020, on all ships sailing internationally.

The major concerns about the IMO 2020 rule are around the sudden increase in demand for compliant fuels globally and the possible safety repercussions from the reactions of ship engines and machinery to fuels of much lower viscosity.

Many ships are temporarily switching to lower sulphur fuels when transiting a Sulphur Emission Control Areas (SECA) such as US coastal waters. However, engineers are concerned about how engines will react to the continuous operation of machinery with the lighter fuel.

In 2015, a 0.10% m/m sulphur limit was set in SECAs; within days there was an increase in vessels losing propulsion and machinery break downs when the operations were switched to the less-polluting marine distillates.

In that year, the US Coast Guard recorded many incidents in SECAs involving leakage caused by the switch to low-viscosity distillate fuels from regular bunker fuel.

The leaks resulted in some fuel pumps seizing up and on-board machinery breaking down, according to a bulletin entitled Loss of Propulsion Incidents (LoPI), published by the California Air Resources Board.

There were also concerns that fires could break out if distillate fuels came into contact with hot surfaces, and machinery break downs if the same fuel was used in cold environments.

The subsequent loss of engine power due to leaky fuel pipes could mean the ship cannot manoeuvre in heavy seas, potentially leading to grounding, capsizing and sinking.

Today, with IMO 2020 looming, engineers are also concerned about the exposure of fractures in engine room pipes that may leak when using lower viscosity fuels. These fractures are not apparent when using thicker Heavy Fuel Oil (HFO).

Another problem is the potential leakage of the lower viscosity oil from flange joints and couplings that form an effective seal for HFO usage. Blended fuels also pose a problem – any instability in the mix could result in variations in viscosity can lead to engine and machinery failure.

The main issue is the lack of standardisation of the new fuels available at present. The International Organization for Standardization (ISO) is developing supplementary advice on the handling of new fuels, and this is due to be published in the coming weeks.