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pipe, hollow structure, usually cylindrical, for conducting materials. It is used primarily to convey liquids, gases, or solids suspended in a liquid, e.g., a slurry. It is also used as a conduit for electric wires.
The earliest pipes were probably made of bamboo, used by the Chinese to carry water c.5000 B.C. The Egyptians made the first metal pipe of copper c.3000 B.C. Until cast iron became relatively cheap in the 18th cent. most pipes were made of bored stone or wood, clay, lead, and, occasionally, copper or bronze. Modern materials include cast iron, wrought iron, steel, copper, brass, lead, concrete, wood, glass, and plastic. Welded steel pipe is made by bending strips of steel into the form of a tube and welding the longitudinal seam either by electric resistance, by fusion welding, or by heating the tube and pressing the edges together. Seamless pipe is made from a solid length of metal pierced lengthwise by a mandrel with a rounded nose.
Steel pipe, introduced in the early 20th cent., is widely used for conducting substances at extremely high pressures and temperatures. Cast-iron pipes, which came into common use in the 1840s, resist corrosion better than steel pipes and are therefore frequently used underground. Clay and concrete pipes usually carry sewage, and concrete pipes are also used to carry irrigation water at low pressures; for moderate pressures, the concrete is reinforced with steel. Seamless copper and brass pipes are used for plumbing and boilers. Because of its softness and resistance to corrosion, lead is used for flexible connections and for plumbing that does not carry drinking water. The chemical and food industries use glass pipes. During World War II manufacturers developed plastic pipe to replace metals that were in short supply. Today PVC pipe is widely used to carry waste water as well as certain corrosive liquids.
A pipeline carries water, gas, petroleum, and many other fluids long distances. In laying oil or gas pipeline, 40- to 80-ft (12- to 24-m) sections of seamless steel pipe are electrically welded together while held over a trench. Before being lowered into place the pipe is coated with a protective paint and wrapped with bonded epoxy or polyethylene sleeves; unwelded sections are typically precoated in the factory. Oil pumping or gas compressor stations located 40 to 75 mi (35–120 km) apart boost the dwindling pressure back up to as much as 1,500 lb per sq. in. The piping must be kept clean, either by applying a negative electrical charge to the pipe or by regular use of a “pig,” or scrubbing ball, inserted at one end and carried along by the current. An oil pipeline 6 in (15 cm) to 24 in (60 cm) in diameter will move its contents at about 3 to 6 mi (5–10 km) per hr.
Water has been moved since ancient times in pipelines called aqueducts. The first natural-gas and petroleum pipelines in the United States were built during the 19th cent. Today in many parts of the world pipelines are an extremely important means of transporting diverse fluids. The Trans-Arabian Pipeline, which carries oil from the Persian Gulf to the Mediterranean, is over 1,000 mi (1,600 km) long. There are more than 180,000 mi (288,000 km) of pipeline in the United States alone.
(1) The common name for wind instruments that are related to single- and double-tube flutes.
(2) A Russian musical instrument (svirel’), a type of double-tube, vertical flute. One of the tubes usually measures from 300 mm to 350 mm long, and the second, from 450 to 470 mm. Each tube has a whistle structure in the upper end and three finger holes in the lower end for altering the pitch. The tubes are tuned a fourth apart. Together, they cover a diatonic scale with a range of a seventh.
(3) In literature, panpipes, which consist of a row of tubes. Kuvikly are also called panpipes.
(or tube), a hollow cylindrical or shaped product whose length is great in comparison to its cross section. In spite of their relatively light weight, pipes are highly resistant to bending and torsion.
Steel and nonferrous metal pipes are made mainly in circular sections, but they are also produced in square, rectangular, oval, and other sections. Cast-iron and nonmetallic pipes and tubing (made of glass, asbestos cement, and plastic) normally have a circular cross section.
Metal pipe and tubing is classified according to method of production as seamless, welded, or cast. Seamless tubing, with an outside diameter of 1–820 mm (for special applications, up to 1,420 mm), is produced from ingots and round bars by drawing or rolling (see). Welded pipe, with an outside diameter of 8–1,620 mm (for special applications, more than 2,500 mm), is made from steel plate, strip, or skelp, with preparatory forming on presses and forming mills (see). Cast pipe, with an outside diameter of 50–1,000 mm, is produced on pipe-casting machines (see).
Steel pipe and tubing is divided into six grades. Grades 1 and 2 are produced from carbon steel. Grade 1, called standard and natural-gas pipe, is used for ordinary applications, such as the construction of scaffolding, partitions, or supports, for laying cables and irrigation systems, and for local distribution and supply of gases and liquids. Grade 2 pipe is used for high-pressure and low-pressure mains for natural gas, petroleum, water, petrochemical products, fuels, and solid substances (see). Grade 3 pipe is used in systems operating under pressure and at high temperatures—for example, in the chemical and food-processing industries, in nuclear engineering, in piping for petroleum cracking plants, and in furnaces and boilers. Grade 4 pipe is used as drill, casing, and auxiliary piping in the prospecting and exploration of petroleum deposits. Grade 5 pipe, or structural tubing, is used in the construction of transportation equipment, such as motor vehicles and railroad cars, in such steel structures as bridge cranes, masts, drilling towers, and supports, and for furniture parts. Grade 6 tubing is used in machine building for production of pump cylinders and pistons, bearing rings, shafts, and other machine parts, and pressure vessels. Steel pipe is divided into three size categories: small (with an outside diameter of up to 114 mm), medium (114–480 mm), and large (480–2,500 mm and more).
Some pipe is heat-treated to improve the structure and properties of the materials. To protect against corrosion and abrasion, pipe can be coated with nonmetallic materials, such as plastic, cement, asphalt, paint, and varnish, or it can be encased in basalt, rubber, glass, or similar materials. Steel pipe and tubing accounts for most of the world production of tubular products.
Cast-iron pipe with an inside diameter of 65–1,000 mm is made from gray cast iron, which is machinable. It is used mainly for water-supply lines (bell-mouthed pressure pipe), in refrigeration plants and acid pipelines (flanged pressure pipe), in the heat exchangers, condensers, and coolers of soda-ash plants (soda-ash pressure pipe), for sewerage systems (nonpressured overflow and sewage pipe), and in gas and petroleum pipelines (nonpressured pipe).
Nonmetallic pipe is manufactured from polymer materials (diameter up to 300 mm), asbestos cement (50–500 mm), reinforced concrete (500–1,600 mm), heat-resistant glass (up to 100 mm), and basalt (up to 1,100 mm). The way in which pipe is produced from various nonmetallic materials is determined by the characteristics of manufacture of the materials. For example, asbestos-cement pipe is produced on pipe-molding machines, and basalt pipe is fabricated by casting in molds (seeSTONE CASTING and ROCK-CASTING INDUSTRY). Plastic pipe is used in water-supply systems. Asbestos-cement and reinforced-concrete pipe is used not only in water-supply systems but also in irrigation and drainage systems. Glass pipe is used for pipelines in the chemical, food-processing, and pharmaceutical industries, and cast-stone pipe is used to convey abrasive materials and slurries in the coal industry and in metallurgy and power engineering.
REFERENCESPolunepreryvnaia otlivka chugunnykh trub. Minsk, 1965.
Shevakin, Iu. F., and A. Z. Gleiberg. Proizvodstvo trub. Moscow, 1968.
See also references under TUBE ROLLING.
M. SH. KAUFMAN
What does it mean when you dream about a pipe?
A pipe may indicate a peaceful outcome to a troublesome situation, as in smoking a “peace pipe.” A pipe may also represent knowledge or contemplation, as symbolized by the stereotypical professor puffing on his pipe. Alternatively, if the pipe in the dream is a conduit, as in a pipeline, then the interpretation may be of communication—hopefully the pipe is clear of rust and corrosion.
grep foo log | more
which feeds the output of grep into the input of more without requiring a named temporary file and without waiting for the first process to finish.
pipe(1) Slang for "communications channel" (line, wire, fiber, etc.). See data pipe, fat pipe and thin pipe.
(2) The symbol for Boolean OR operations, which is the Shift-Backslash key on a computer keyboard. For example, to search for Dell or Toshiba laptops in Google, the pipe symbol can be used instead of upper case OR as follows:
laptops (dell | toshiba) laptops (dell OR toshiba)
(3) The symbol for a shared space that accepts the output of one program for input into another. In Windows, DOS and Unix, the pipe command is a vertical line (|). For example, the DOS/Windows command dir | find directs the output of the directory list to the FIND filter. In Unix/Linux, the statement ls | wc directs the directory list output to the word count function to count the number of files. See ls and filters and pipes.