Pipeline

Pipeline, tube for conveying fluids—liquids, gases, or slurries. Pipes vary in diameter considerably, according to the flow rate required and the pressure gradient. Materials used include steel, cast iron, other metals, reinforced concrete, fired clay, plastic, bitumenized-fiber cylinders, and wood. They are often coated inside and out with bitumen or concrete to prevent corrosion. Concrete, plastic, and steel pipes can now be made and laid in 1 continuous process, but most pipes still need to be joined by means of welding, screw joints, clamped flange joints, couplings, or bell-and-spigot joints caulked with lead or cement. Pipelines, consisting of long lengths of pipe with valves and pumps at regular intervals (about 60 mi/98 km for oil pipelines), are used chiefly for transporting water, sewage, chemicals, foodstuffs, crude oils, and natural gas.