Two fuel oil circulation pumps take suction from the venting tank and discharge to the fuel oil circulating line, supplying fuel oil to the injection system of the main engines and of the diesel generators.The circulating line is equipped with two steam heated fuel oil heaters, one back flush fuel oil filter, one bypass filter and one viscosity controller. The capacity of each heater is sufficient for the max consumption for the main engines and the diesel engines.There is a facility to run the diesel generators on marine diesel oil with the main engine on heavy fuel oil.