How to select Marine Fuel Oil and Factors Necessary for Fuel Oil System on Merchant Ships

Maritime Transport utilises lowest grade of fuel to run its propelling plant. This is one of the reasons which make it the cheapest mode for transporting goods to different countries. However, by using such low grade fuel, eco system can be severely damaged from harmful exhaust of the ships.

To reduce such causes of pollution, several guidelines are made which helps in reducing emission from the ship as well as offer ways to make the process of running the massive main propulsion plant and other auxiliary services on board ship more economical.

Marine fuel oils used for merchant ships are selected as per the requirements laid down by the regulation authority under MARPOL and according to the area where the ship usually functions. On the basis of these factors, along with several others, marine fuel oil and fuel oil system selection is done.

On what basis is Marine Fuel Oil Selection done?

• If the fuel is derived from petroleum process then it should be a blend of hydro carbons derived from refining and it may contain additives.

• The fuel oil should be free from inorganic acids

• It should not exceed NOx as required by the regulation in MARPOL Annex VI

• It shall not exceed sulphur content more than 3.5% globally and 1.0% for special areas

• Flash point of the fuel used onboard ship must be at least 60 °C

• For fuel used in emergency generator, lifeboat and other emergency appliance flash point must be at least 43 °C

Factors Necessary for a Fuel System Installation and working

• All fuel tanks except double bottom tanks must be outside Category A machinery space of the ship

• The biggest fuel bunker tank on ship should have maximum capacity not more than 2000m³

•  The entire fuel oil tank within machinery spaces must be provided with quick closing valve operational from remote position.

• Fuel tank sounding pipe inside the engine room must be fitted with self closing device

• Vent must be provided to all tanks to prevent over pressurising

• High Level alarms must be fitted in all fuel oil tanks to avoid oil spill

• Pipes used for fuel oil must be of steel and as per the required pressure of the system

• Stop valve provided on inlet and outlet of fuel oil filters and pumps

• Material for valves used in fuel system is steel or spheroidal cast iron

• All high temperature pipes are covered with heat retardant lagging

• All high pressure pipe used in injection system must be double jacketed or double walled type