The picture on the left is a cargo tank after unloading Heavy Fuel oil, it is black and smoky, it is heavy lower fraction oil used for fueling ships and factory generators and old style electricity power plants and the like, smoky because it has been heated to 85 or 90 degrees Celcius to get it out of the tank. The pump won’t get any decent suction if it’s cooler than 50 degrees Celcius the viscosity jumps for every degree colder it gets. Tricky because you have to stop heating before you empty the tank or rlse the heating coils will get too hot….. Heavy dirty smelly poisonous and a bastard to get clean after.
The picture on the right is the same tank 5 days later after cleaning, first soaked in diesel then washed with near boiling water and finally with a high pressure water jets. Ready for loading clean products again. The silver pipes are the stainless steel heating coils filled with thermal oil which heats the cargo. Next cargo? Ultra Low Sulphur Diesel, the really environmentally friendly fuel called City Diesel and Green Diesel. Drive carefull now!
Hi Tim,
For several years I sailed on a dedicated fuel oil carrier and I remember that temperature of cargo was my most common nightmare… we used to load all sort of different grades of fuel (low sulphur, residual, bunker fuel, etc.). Stripping the tanks was always a stressful task, with the temperature dropping and the “liquid” going “solid”… poor pumps.
On that tanker we only carried fuel so we didn’t have to tankwash between voyages, unless we had to prepare the vessel for drydock, and the heating coils were fed by steam. As I would learn later, fuel is even dirtier than crude (although less dangerous…).
Nevertheless it was my first vessel which I will always remember.