Skuld has issued fresh guidelines for tank cleaning ahead of the new 0.50% sulfur cap on marine fuel.
The so-called IMO2020 rule comes into force from January 1, 2020, and the vast majority of vessels are expected to switch to low sulfur fuel for compliance.
"Most of these ships will have been using high viscosity High Sulphur Fuel Oil (HSFO) based primarily on residual fuel oils," writes Skuld Technical Manager, Dick Farrel Camoying.
"Such fuels tend to stick to the inside of fuel tanks forming layers of semi-solid substances containing sediments and asphaltenic sludge. Such residues will also typically have solidified and settled in various parts of the fuel oil service system including pipelines, settling and service tanks."
There are various options for such cleaning, ranging from manual cleaning, the use of chemicals, to simply flushing with compliant fuel ahead of time.
However, Camoying notes that it is not practical for the entire fleet to undergo dry docking during a very short period, so options should be carefully considered.
The length of time since the last cleaning of the tanks, as well as the condition of the tank and its shape will all impact the timing and effectiveness of any cleaning process.
Skuld's guidance in full can be found here: