A colorless, flammable hydrocarbon gas, C4 H10, a saturated aliphatic existing in two isometric forms: used chiefly in the manufacture of rubber and as fuel. (E.g. camping gas)


An olefinic hydrocarbon recovered from refinery processes.


A colorless flammable gas with an unpleasant odor.


A substance which affects, initiates, or accelerates reactions without itself being altered.


A mixture of hydrocarbons that exists in liquid phase in natural underground reservoirs and remains liquid at atmospheric pressure after passing through surface separating facilities. The primary feedstock used to make gasoline, diesel, jet, residual fuel and other finished petroleum products.

Crude Distiller

An oil refinery unit that separates crude oil into different products according to their individual boiling point ranges. Distillation allows for the materials to be separated without being subjected to conditions that would cause cracking or decomposition.

Deadweight Tonnage (DWT)

The number of tons of 2,240 pounds that a vessel can transport of cargo, stores and bunker fuel. It is the difference between the number of tons of water a vessel displaces “light” and the number of tons it displaces when submerged to the “load line”.


Product from a distillation process.


The lightest of all gases, occurring mainly in combination with oxygen in water; exists also in acids, bases, alcohols, petroleum, and other hydrocarbons.

Hydro Treating

A refining unit whereby processed material from the crude units is treated in the presence of catalysts and hydrogen, to remove sulfur and other unwanted substances. The hydrotreater is often the critical unit for producing gasoline, low-sulfur diesel and naphthenic base luboils.

Lubricating Oils

Substances used to reduce friction between bearing surfaces or as process materials either incorporated into other materials used as processing aids in the manufacture of other products, or used as carriers of other materials. Petroleum lubricants may be produced either from distillates or residues. Lubricants include all grades of lubricating oils from spindle oil to cylinder oil and those used in greases.


Mercaptans are also known as thiols of which the simplest one is methylthiol or methylmercaptan. They are chemically harmless and have been described as having the stench of rotting cabbages or smelly socks.

Methylmercaptan is often added to natural gas, which is colorless and odorless, to make it easier to detect leakages.


An olefinic hydrocarbon recovered from refinery processes or petrochemical processes.


Liquid capable of dissolving another substance.


Straight-run gasoline fraction. Used as a feedstock for reforming and as a petrochemical feedstock.

Vacuum Distillation

Distillation under reduced pressure, which lowers the boiling point of the liquid being distilled. This technique prevents cracking or decomposition of the charge stock.