Floating storage of very low sulphur fuel oil (VLSFO) can cause some of these blended fuels to sludge, blocking pipes and filters on board vessels as asphaltenes increase during the period when the fuel remains unused.
According to MABUX concerns for the quality of VLSFO bunker fuel have arisen because of the continued “Weakness in prices and slow demand”.
Some reports suggest that after around 90 days of storage, “Asphaltenes start to precipitate and sludge problems could develop. The sludge...
https://container-news.com/concerns-over-fuel-quality-after-long-vlsfo-storage/