Managing the changeover to low sulphur fuel

Aerial view of a ship in the water

Ensuring compliance with the International Maritime Organization’s (IMO) 0.50 per cent sulphur cap isn’t just about fuel selection; the actual switchover process from heavy fuel oil (HFO) to new, low-sulphur alternatives needs careful management.

First, operators will need to ensure that their fuel tanks do not contain high-sulphur HFO by the IMO deadline. Fuel tanks will probably retain sediment from previous bunkers, which is likely to contain high levels of sulphur. If this is not removed, there is the risk that it will contaminate compliant fuel, pushing its sulphur content above the 0.50 per cent limit.

ExxonMobil expects that many compliant fuels entering the market will have sulphur content very close to the 0.50 per cent cap, so even very low levels of residual sulphur left in a fuel tank could tip a vessel over the IMO’s limit.

To minimise this risk, ExxonMobil recommends that vessel operators flush fuel tanks with a distillate-based product to help remove sludge deposits. This process may need to be repeated, depending on the amount of residue present. In some instances, tank bottoms may have to be manually cleaned. Vessel operators must factor in how long these processes could take and keep in mind that any sludge removed from the tanks will need to be disposed of properly.

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