Trans-Alaska pipelineIn 1977, the $7.7 billion trans-Alaskan oil pipeline opened. The $7.7 billion project links oil fields in Prudhoe Bay to the shipping port of Valdez, where oil arrives 38 days later. Because of the earth's heat at greater depths, oil pumped from the Prudhoe Bay field, which is 10,000-to-20,000 feet deep, is at about 145 to 180 degrees F. Using heat exchangers that work like a car's radiator, the oil companies cool the oil to about 120 degrees before it enters the pipeline. The pipe is a tube of 1/2-inch thick steel with a diameter of 48 inches, wrapped with four inches of fiberglass insulation and a cover of aluminum sheet metal. Where it snakes over land, the pipeline is supported by posts designed to keep permafrost frozen. |
