Residual fuel oil

Heavy fuel oil produced from the residue in the fractional distillation process rather than from the distilled fractions. No. 6 fuel oil is the most common product used to generate electricity.

The heavier oils that remain after the distillate fuel oils and lighter hydrocarbons are distilled away in refinery operations and that conform to ASTM Specifications D396 and D975. Included are No. 5, a residual fuel oil of medium viscosity; Navy Special, for use in steam-powered vessels in government service and in shore power plants; and No. 6, which includes Bunker C fuel oil and is used for commercial and industrial heating, electricity generation, and to power ships. Imports of residual fuel oil include imported crude oil burned as fuel. See crude oil, hydrocarbons.