Abstract

Pipelines are continuous large-diameter pipes, usually buried underground, for transporting gases, liquids, or solid slurries over distances ranging from a few to several thousand kilometers. The largest uses are the transport of natural gas or crude oil from producing fields to terminals or processing plants, or petroleum products from oil refineries or natural gas processing plants to distribution points. Pipeline systems in the oil and gas industries consist of small-diameter gathering pipelines that carry oil or natural gas from producing, wells, and large-diameter cross-country pipelines with either compressor stations (for gases) or pumping stations (for liquids) along the route to maintain flow velocities over great distances. Small-diameter pipe in distribution systems is not part of a pipeline system. Despite great similarities between gas and liquid pipelines in these industries, their regulation has been significantly different. Pipelines are also used to transport anhydrous ammonia, hydrogen, carbon dioxide, molten sulfur, chlorine, nitrogen, oxygen, helium, and other liquid or gaseous chemicals. Freight pipelines transport solids, either as finely divided particles slurried in water or other fluids, or encased in capsules propelled by compressed air or flowing water. Slurry pipelines transport coal, iron ore, phosphate rock, mine-tailings, municipal wastes, wood fibers, and other finely divided solids suspended in water, the slurry often being dewatered at the terminus. Pipeline transport of materials is probably the safest, least costly, and most environmentally benign of all forms of over-land transport of materials.