The contact between two surfaces under pressure and subject to a slight relative motion.

Keyed-taper connections, splines, bolted connections and clamped flanges give rise to fretting failure. The basis is two surfaces which are able to move relatively to each other, even by a small amount, leading to contact scars.

Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other.

A non-dimensional number indicating the relation between a vessel’s length and its speed, expressed as Fn = V / √gL ; where V = speed, g = acceleration due to gravity, L = length of the vessel

A fuel is any material that can be made to react with other substances so that it releases energy as heat energy or to be used for work.

The fuel assembly of nuclear fuel usually consisting of uranium or uranium–plutonium mixes.

A fuel cell is an electrochemical cell that converts the chemical energy of a fuel (often hydrogen) and an oxidizing agent (often oxygen) into electricity through a pair of redox reactions.

A fuel cell power pack consists of a fuel and gas processing system (the balance of plant), and a stack of fuel cells that convert the chemical energy of the fuel to electric power through electrochemical reactions.

The fuel cladding is the first layer of protection around the nuclear fuel and is designed to protect the fuel from corrosion that would spread fuel material throughout the reactor coolant circuit.

A new automated two-stage fuel oil supply module developed by Alfa Laval.

A measure of how well fuel can be converted into mechanical work or motion.

A fuel element failure is a rupture in a nuclear reactor's fuel cladding that allows the nuclear fuel or fission products, either in the form of dissolved radioisotopes or hot particles, to enter the reactor coolant or storage water.

Fuel gas is any one of a number of fuels that are gaseous under ordinary conditions.

Fuel injection is the introduction of fuel in an internal combustion engine, most commonly automotive engines, by the means of an injector.

Fuel derived from the distillation of crude oil. There are a number of variations such as Heavy, medium and light fuel oils which have differering specifications such as specific gravity and calorific value.

see fuel oil systems.

An oil fuel tank that contains only the required quality of fuel ready for immediate use. Two oil fuel service tanks, for each type of fuel used on board, necessary for propulsion and generator systems, are to be provided.

Fuel oils are produced from various crude oils and refinery processes. Due to incompability, such fuels can occasionally tend to be unstable when mixed.

Various piping systems, provided for bunkering, storage, transfer, offloading and treatment of fuel oils.

Old vessels, but unfortunately also many new ones, have bunkers in double hull and any shell damage can result in oil spill. This common practice has been stopped by new revised MARPOL Annex I, Regulation 13A.