Pipeline is a system of pipes that transports certain substances over long distances. Pipelines play an important role in the operation and the economy of modern communities. They carry most of the water used in homes, businesses, and industry, and transport natural gas, petroleum, and such petroleum products as gasoline, kerosene, and diesel fuel. They also carry industrial waste and sewage, and particles of coal, iron ore, and limestone used for industrial purposes.
Many pipelines consist of a series of steel pipes welded together. But many gas and water pipelines are made of such plastics as polyethylene and polyvinyl chloride. Pipelines are also made of aluminum, concrete, iron, or a combination of asbestos and cement. Water pipelines are often built in segments connected at joints with watertight gaskets or sealing materials.
A pipeline may be more than 3,000 miles (4,800 kilometers) long. Pipelines range in diameter from about 1/2 inch (1.3 centimeters) to 15 feet (4.6 meters). Most pipelines are buried at least 2 feet (0.6 meter) underground. Some are laid on the ground or along supports above the ground. Some lines are laid underwater. Pipelines run across deserts, over mountains, and under rivers and lakes.
Pipelines are among the most efficient means of transportation. They deliver large quantities of materials in a continuous flow directly from a supplier to a user. A pipeline 650 miles (1,050 kilometers) long and 40 inches (102 centimeters) in diameter can transport about a million barrels of petroleum a day. Although pipelines are expensive to build, they are relatively cheap to operate and maintain. They distribute more fuels used as energy—chiefly petroleum, petroleum products, and natural gas—than do any other means of transportation.
In the United States, about 220,000 miles (355,000 kilometers) of pipelines carry crude oil and petroleum products to refineries and market areas. Natural gas travels to processing plants and communities through a network of about 1.6 million miles (2.6 million kilometers) of pipelines. Canada has more than 52,000 miles (84,000 kilometers) of pipelines that carry either petroleum or natural gas.
Kinds of pipelines
There are three chief kinds of pipelines: (1) gas pipelines, (2) liquid pipelines, and (3) solids pipelines.
Gas pipelines
carry mainly natural gas. Pipes called gathering lines transport gas from a well to processing plants. The processed gas is then fed into transmission pipelines, which carry it to cities and towns. There, it flows to consumers through distribution lines. There are two kinds of distribution lines, mains and individual service lines. Mains are pipes connected to transmission pipelines. They typically range in diameter from 2 to 24 inches (5 to 61 centimeters). Service lines branch off the mains, and most are 2 inches (5 centimeters) or less in diameter. They carry the fuel sold by utility companies to homes, offices, factories, and other consumers.
Liquid pipelines
carry chiefly petroleum, petroleum products, and water. In transporting petroleum, gathering lines take the oil from the well to trunk pipelines. Some trunk lines move the oil directly to refineries. Others take it to shipping points for delivery to refineries by tankers, barges, railroad cars, or trucks. The refineries use the petroleum in making gasoline, lubricating oil, and other products, which are carried to market areas through product pipelines.
Water-transmission pipelines bring water to cities and towns from lakes, reservoirs, wells, and other sources. The water then flows into distribution pipelines, through mains, and into service lines that lead to buildings in the community. Pipes inside each building distribute the water to faucets, toilets, and other plumbing fixtures. Another network of pipes carries wastewater and sewage from these fixtures through drains and sewers. Water pipelines also supply water for agricultural and industrial uses, such as in irrigation systems and mining operations.
Solids pipelines
transport most materials in the form of slurries, which are mixtures of liquids and finely ground solid particles. Slurries include coal and water, iron ore and water, limestone and water, and coal and oil. They flow like liquids, and pipelines that carry slurries resemble liquid pipelines. Solids pipelines transport certain materials, such as sawdust and wheat, by means of air flowing through the system.
How pipelines work
Pipelines use tremendous pressure to transport the substances being carried through them. This pressure usually ranges from 50 to 2,000 pounds per square inch (34 to 1,379 newtons per square centimeter) at the beginning of the pipeline. It moves natural gas at about 15 miles (24 kilometers) per hour and liquids and slurries at 2 to 5 miles (3 to 8 kilometers) per hour.
As the substance travels through the line, the pressure propelling it decreases because of friction of the material against the walls of the pipe. Therefore, the material requires a boost of energy every 30 to 150 miles (48 to 241 kilometers) to push it along. This energy is supplied by compressor stations for gas pipelines and by pumping stations for liquid and slurry lines. The flow of material through a pipeline may also be regulated by control valves along the route.
Several materials at a time can be transported by pipelines that carry petroleum products. The different materials are pumped through the line one after the other in “batches” at least 15 to 20 miles (24 to 32 kilometers) long. The materials are arranged so that the most valuable substances are separated from the least valuable. This arrangement reduces any damage that may result if some of the products get mixed together. Near the end of the line, an instrument called a gravitometer determines the dividing line between products by measuring the differences in their weights.
Pipelines are continually inspected for leaks and for damage caused by such conditions as corrosion, freezing temperatures, heavy rain, and soil erosion. The locations of underground pipelines are marked to prevent damage from any future construction projects. A coating of tar or some other substance helps protect pipelines against corrosion. Special control devices are installed in pipelines to minimize damage to the environment that may be caused by breaks in the line.
Many people believe that pipelines should not be built in certain areas. Environmentalists fought for years to prevent the construction of the Trans-Alaska Pipeline, which opened in 1977. They argued that the pipeline and the heat of the oil traveling through it could upset the delicate ecological balance of the frozen land. Some conservationists oppose the construction of slurry pipelines in the Western United States. They believe the limited water resources of the region are needed for agricultural purposes and should not be used in slurry.
Major pipelines of the world
In the United States,
an extensive network of pipelines crisscrosses the country. One of the longest of these pipelines carries natural gas from Baton Rouge, Louisiana, to Pittsburgh, Pennsylvania, Philadelphia, and New York City. It is about 2,000 miles (3,200 kilometers) long and has about 8,000 miles (13,000 kilometers) of branch lines.
The Trans-Alaska Pipeline was built to help reduce the nation’s fuel shortage by tapping Alaska’s vast oil reserves. The pipeline runs about 800 miles (1,300 kilometers) from Prudhoe Bay on the Arctic Ocean in the north to Valdez on the southern coast of Alaska.
In Canada,
about 80 percent of the nation’s petroleum and natural gas comes from Alberta. Pipelines move these resources to more heavily populated areas. For example, the Interprovincial Pipeline carries oil about 2,500 miles (4,020 kilometers) from Redwater, Alberta, to Montreal, Quebec. The Trans-Canada Pipeline carries natural gas almost 2,300 miles (3,700 kilometers) from the Alberta-Saskatchewan border to Montreal.
In other countries.
The nations of the Middle East rely heavily on pipelines to transport the region’s huge production of oil. For example, the Trans-Arabia Pipeline runs about 750 miles (1,200 kilometers) across Saudi Arabia between the Persian Gulf and the Red Sea. The Trans-Arabia Pipeline eliminates the need to use the shipping lanes through the Strait of Hormuz, between Oman and Iran.
One of the world’s longest pipelines, the Export Pipeline, delivers natural gas more than 4,000 miles (6,400 kilometers), from western Siberia to Austria, Belgium, France, Germany, Italy, and the Netherlands. Another pipeline, eastern Europe’s Friendship Pipeline, transports oil about 1,625 miles (2,615 kilometers) from the Ural Mountains in Russia to the Czech Republic, Germany, Hungary, Poland, and Slovakia.
The South European Pipeline carries oil nearly 500 miles (800 kilometers) from Lavera, France, to Karlsruhe, Germany. In China, the oil fields in the northeastern region are linked with Qinhuangdao, a port on the Yellow Sea, by a 715-mile (1,151-kilometer) pipeline.
History
The first pipelines of historical importance made up part of the water distribution system of ancient Rome. This system was more than 380 miles (612 kilometers) long and may have carried up to 320 million gallons (1.2 billion liters) of water daily. It was constructed so that the force of gravity carried the water through the system. In 1582, the first pumps for pipelines were installed in the water system of London.
During the mid-1800’s, pipelines started to become an important part of the water distribution system of the United States. The nation’s first successful oil pipeline was laid in 1865. It carried about 800 barrels of oil a day from an oil field near Titusville, Pennsylvania, to a railroad 5 miles (8 kilometers) away. The first major natural gas pipeline in the United States was completed in New York in 1872. This line delivered gas from West Bloomfield to Rochester, a distance of about 25 miles (40 kilometers). In 1879, a 110-mile (177-kilometer) oil pipeline began to operate in Pennsylvania. This pipeline carried about 10,000 barrels of oil a day from Coryville, near Bradford, to Williamsport.
The pipeline industry grew rapidly after the development of seamless, electrically welded pipe in the 1920’s. This kind of pipe was much stronger than earlier types. It could carry materials under greater pressures and, thus, in larger quantities. It enabled gas and oil companies to build profitable pipelines more than 1,000 miles (1,600 kilometers) long. Today, such lines make up a network that carries oil and natural gas from the major producing areas to every part of the United States.
See also Coal (Shipping coal) ; Gas (Transmitting and distributing gas) ; Petroleum (Transporting petroleum) ; Water (City water systems) .
