A gas pipeline is a network of pipes that are used to transport gas across a vast distribution network. In the context of energy and civil engineering, pipelines are used to distribute various fluids, such as oil, oil products, or natural gas. These oil and gas pipelines form extensive distribution networks.
In the energy sector, there are two major types of pipelines: liquids pipelines and natural gas pipelines. Liquid pipelines are used to transport either crude oil or natural gas in liquid form. These substances then go to refineries where they're subject to distillation and production processes. Some liquid pipelines may also be used to transport distilled petroleum products to distribution centers.
Largely, however, natural gas pipelines are the ones used for distribution. These pipelines transport natural gas to processing plants and are used for distribution purposes-natural gas is often delivered directly to homes through such pipelines.
Within these two categories, there are also four subcategories that describe pipelines of different sizes and purposes: gathering lines, feeder lines, transmission pipelines, and distribution pipelines. The combination of these four types of lines make up the complex network of natural gas pipelines that we see in countries throughout the world.
Pipelines made for gathering and transmission are usually made of steel, but a select few are made from plastic, iron, composite, or other materials. Most gas pipelines are made of steel, but the type of pipe material used in a pipeline normally depends on the expected service requirements and predicted operational parameters for the pipelines.
The steel pipe used in the construction of these pipelines can range in size, reaching from several inches in diameter to several feet. In terms of length, they can be anywhere from hundreds of feet to hundreds of miles long.
Typically, the steel pipe necessary for constructing gas pipelines is manufactured according to strict design specification. It's often produced in 40-foor sections that are joined together in the field with welding tools when the pipeline is being constructed.
Another important distinction when it comes to pipeline materials is uncoated versus coated pipelines. Some gas and hazardous liquid pipelines are uncoated and are known as bare steel pipelines. Most of this type of pipeline has been taken out of service and is no longer used in constructing new pipelines today, but there are a few that continue to operate.
Gas flow through a pipeline due to the results of a serious of compressors creating pressure differentials. In other words, natural gas flows from an area of high pressure to an area of lower pressure, following the natural laws of physics. The compressors are powered by electric or natural gas-fired engines that compress the incoming gas and then push it out at an increased rate of pressure.
There are a few gathering systems out there that actually don't need compressors. Why? In some cases, the natural gas coming out of the wells has enough pressure to move through the gathering lines on its own. As you might expect, the compressors needed for large transmission lines are significantly larger than those compressors used to move gas through smaller distribution lines-such as the ones that go directly to houses and residential locales.
In transmission pipelines, natural gas is typically compressed to pressures between 500 and 1400 pounds per square inch. The compressor stations on these pipelines are normally built every 50 to 100 miles along the length of the pipeline. This is just about the required distance to ensure the pressure can keep the gas moving.
Some transmission pipelines are built to be what's called bidirectional. This means that gas can come from both ends of the pipelines, depending on where the gas is gathered from. In other words, the compressors can be used to create varying pressure differentials, meaning gas can flow in either direction in the pipeline.
Oil pipelines transfer liquid petroleum in its crude format, while gas pipelines transfer natural gas and biofuels, Although they might seem similar, oil and gas pipelines have many important differences, ranging from capacity, speed, temperature, impact and power source.
These different types of pipelines operate at very different speeds. Oil pipelines generally move faster than their gas counterparts. Their storage capabilities are also different. While the pipe's area itself is fixed, natural gas is fare more compressible than crude petroleum, so gas pipelines can carry more fuel at once.
Gas pipelines can also be kept at lower temperatures than oil pipelines. Oil pipelines require additional heat to ensure they don't get clogged. Going along with this point, crude oil pipelines have a far more drastic impact on the environment. If sudden leakage occurs, crude petroleum pipelines can have dramatic consequences and the leak can catch fire quite easily.
Finally, the two pipelines have different sources of power. Oil pipelines are typically powered by a centrifugal pump whereas gas pipelines are powered by a compressor and the pressure differentials that it creates.
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