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a long pipe, esp underground, used to transport oil, natural gas, etc., over long distances


A line of pipe connected to valves and other control devices, for conducting fluids, gases, or finely divided solids.


A line of piping and the associated pumps, valves, and equipment necessary for the transportation of a fluid. Major uses of pipelines are for the transportation of petroleum, water (including sewage), chemicals, foodstuffs, pulverized coal, and gases such as natural gas, steam, and compressed air. Pipelines must be leakproof and must permit the application of whatever pressure is required to force conveyed substances through the lines. Pipe is made of a variety of materials and in diameters from a fraction of an inch up to 30 ft (9 m). Principal materials are steel, wrought and cast iron, concrete, clay products, aluminum, copper, brass, cement and asbestos (called cement-asbestos), plastics, and wood.

Pipe is described as pressure and nonpressure pipe. In many pressure lines, such as long oil and gas lines, pumps force substances through the pipelines at required velocities. Pressure may be developed also by gravity head, as for example in city water mains fed from elevated tanks or reservoirs.

Nonpressure pipe is used for gravity flow where the gradient is nominal and without major irregularities, as in sewer lines, culverts, and certain types of irrigation distribution systems.

Design of pipelines considers such factors as required capacity, internal and external pressures, water- or airtightness, expansion characteristics of the pipe material, chemical activity of the liquid or gas being conveyed, and corrosion.


A sequence of functional units ("stages") which performs a task in several steps, like an assembly line in a factory. Each functional unit takes inputs and produces outputs which are stored in its output buffer. One stage's output buffer is the next stage's input buffer. This arrangement allows all the stages to work in parallel thus giving greater throughput than if each input had to pass through the whole pipeline before the next input could enter.

The costs are greater latency and complexity due to the need to synchronise the stages in some way so that different inputs do not interfere. The pipeline will only work at full efficiency if it can be filled and emptied at the same rate that it can process.

Pipelines may be synchronous or asynchronous. A synchronous pipeline has a master clock and each stage must complete its work within one cycle. The minimum clock period is thus determined by the slowest stage. An asynchronous pipeline requires handshaking between stages so that a new output is not written to the interstage buffer before the previous one has been used.

Many CPUs are arranged as one or more pipelines, with different stages performing tasks such as fetch instruction, decode instruction, fetch arguments, arithmetic operations, store results. For maximum performance, these rely on a continuous stream of instructions fetched from sequential locations in memory. Pipelining is often combined with instruction prefetch in an attempt to keep the pipeline busy.

When a branch is taken, the contents of early stages will contain instructions from locations after the branch which should not be executed. The pipeline then has to be flushed and reloaded. This is known as a pipeline break.


A sequential channel in which data, instructions or signals are moved from one point to another. See pipeline processing and graphics pipeline.
References in periodicals archive ?
Indeed, for years Congress and the NTSB had been asking OPS to require pipeline operators to radically improve inspections of equipment and training of employees who monitor the pipelines.
The court applied the test enunciated in Plainfield Union in determining if Badger's pipeline relocation costs were currently deductible.
Samo said he was confident that oil companies would voluntarily replace their acetylene-welded pipelines because they fear the cost of a spill cleanup.
The Cajon-EPTC project proposal, which includes the use of an already existing pipeline, was not been addressed in the draft environmental report when it was circulated last year.
The Fayetteville Lateral, consisting of approximately 167 miles of 36 inch pipeline with an initial design capacity of 800,000 MMBtu per day and a maximum capacity of 1.
Our new pipeline has been designed to give our storage customers significant additional take-away capacity and to provide new transportation alternatives to gas producers and other shippers in the Barnett Shale.
Current pipeline capacity in the region is not sufficient to accommodate this growth, creating an outstanding opportunity for Enterprise to combine elements of its North Texas midstream infrastructure with the new Sherman Extension project to provide a comprehensive export solution for producers and gatherers from this region.
After months of preparation including permitting, rights-of-way acquisition, engineering design and materials procurement, it is exciting to see the actual construction of this pipeline begin," stated Irv Toole, President and Chief Executive Officer of Pacific Energy.
The Shenzi pipeline will provide producers in the area with access to the premier oil markets in both Texas and Louisiana and offer additional benefits for Enterprise through our ownership interest in the Cameron Highway and Poseidon oil pipelines.
The Partnership's actual results, performance or achievements could differ materially from those expressed or implied in this release as a result of certain factors, including competition within the energy industry, climactic conditions and the price of gas in the Appalachian and Mid-Continent areas, actual versus projected volumetric production from wells connected to the Partnership's gas-gathering pipeline system, and the cost of supplies and services in the energy industry.