Pipeline
A gas pipeline or gas pipeline is a pipeline used to transport combustible gases on a large scale. In today's economic activity, its role is very important.
Construction
It consists of a pipeline through which combustible gases, mainly natural gas, circulate at high pressure from a point of origin to a distribution center. They are built buried in trenches at a usual depth of one meter and up to two meters, depending on the terrain and security. Exceptionally, they are built on the surface.
For safety reasons, the regulations of all countries establish that valves be placed in the gas pipelines at certain intervals, through which the flow of gas can be cut off in the event of an incident (such as a lack of pressure due to a leak Of gas). In addition, if the pipeline is very long, it may be necessary to locate compression stations at intervals, as well as fiber optic cables (for the transmission of information and the detection of gas leaks in the pipeline), emergency stations, equipment against fires and roads to access the place of the gas leak.
The beginning of a gas pipeline can be a field or a regasification plant, generally located in the vicinity of a maritime port where ships arrive (for natural gas, they are called methane tankers), which they transport liquefied natural gas in cryogenic conditions of very low temperature (−161 °C). They are also built to connect gas plants with bottling plants in cities, for filling gas cylinders, or for distributing it through pipelines to cities, consumption centers, industries, and power generation plants.
To cross a river in the route of a gas pipeline, two main techniques are used: horizontal drilling and directional drilling. With them it is achieved that both the flora and fauna of the river and the riverbank are not affected. These techniques are also used to cross other important infrastructure such as roads, highways or railway lines.
Laying by sea is done from specially designed ships, which deposit the pipe on the seabed once it has been welded on the ship, with a special pipe installation system as in the North Sea, England, Norway and Russia, with large ships that function as pipe factories and deposit the pipe on the bottom of the sea.
Particular regulations in many countries require buried gas pipelines to be protected from corrosion. Often the cheapest method is to coat the conduit with some type of polymer so that the pipe is electrically insulated from the surrounding ground. It is generally covered with paint and polyethylene up to a thickness of 2-3 mm. To prevent the effect of possible failures in this coating, gas pipelines are usually equipped with a cathodic protection system, using sacrificial anodes that establish sufficient galvanic voltage so that corrosion does not occur in the tube, anodes that must be changed during its operation. exploitation over the years.
The environmental impact produced by gas pipelines focuses on the construction phase of the pipeline. Once this phase is finished, all the impacts associated with the modification of the terrain, the movement of machinery, etc. can be minimized. It only remains to verify the effectiveness of the corrective measures that should have been taken, based on the changes made: reforestation, reforestation, protection of margins, roads, etc.
The operator of the gas pipeline, which can be a public, mixed or private company, must establish the protection strips (withdrawals) on each side of the gas pipeline, which may be 10 meters and up to 30 meters on each side of the gas pipeline, depending on the diameter, capacity and pressure of the pipeline; It will not be possible to build houses, buildings, roads, bicycle lanes, train lines and plant trees, within the strips assigned to each type of pipe by official regulations or by the gas pipeline operator.
In general, in Europe all gas pipelines are compulsorily subjected to environmental impact assessment procedures by the competent authorities. In this procedure, environmentally sensitive areas and protected spaces are identified, among others, potential impacts are evaluated and corrective actions are proposed, pipes cannot be installed near water sources and populated areas, but the government has the power to expropriate properties, land, agricultural plantations and houses, in case it is necessary to build a new gas pipeline, in the same way as it happens with the construction of a railway line, road or bridge in different places, and establish new withdrawal zones for the pipeline, where house construction permits cannot be issued in the future, houses, buildings, walls and roads cannot be built on the pipeline construction route and the pipeline withdrawal zone, established by the government, the construction company or the public or private company that manages the gas pipeline.
Gas circulation
The pressure at which the gas circulates through the gas pipeline is normally 72 bar for those of the basic transport networks and 16 bar in the distribution networks in the cities.
To bring gas to homes and businesses, the transportation pressure must be lowered to reasonably safe limits. This is achieved by installing regulation stations along the pipeline in which the pressure is lowered to the usual distribution pressure in the cities.
The pressure change is done analogously to electrical networks (high voltage/low voltage). In this case, regulation and measurement stations are used; Membrane pressure regulators regulate the output pressure that is needed in the different pipes. The higher the pressure inside the system, the larger the diameter of the pipe; Pipes for distribution networks in homes and buildings have lower pressure and smaller diameter.
The longest gas pipeline in the world is the Nord Stream built under the Baltic Sea between Russia and Germany; It includes two parallel branches, each one 1,224 km long, 1,220 mm (48 inches) in diameter, 22 MPa (220 bars) of pressure and a transport capacity of 27,500 million m³ of natural gas per year.
The first branch began to be built in April 2010 by the Gazprom company; it was completed in June 2011. Construction of the second branch began in May 2011 and its commissioning is scheduled for the end of 2012. The South Stream gas pipeline began construction in 2012, between Russia and Europe, under the Black Sea and It will reach Italy and Austria. The Blue Stream gas pipeline is an extension of the Trans-gas and Yamal-Europe gas pipeline between Russia and Europe, which runs from Russia to Turkey. Another construction project is the Nabucco Pipeline to transport gas from the Middle East to Europe via Turkey.
Long-length gas pipelines pass through several countries and are built jointly by several oil companies, with financing from England, Germany, Russia, France, Italy, Norway and China, which participate as partners in the project and receive profits for the transportation of gas in pipelines to final consumers and for gas exports.
In America, construction of the Texas-Tuxpan marine gas pipeline began on May 19, 2017. It will connect South Texas, United States with the Mexican states of Tamaulipas and Veracruz. Due to its length, it is one of the largest currently being built under the sea. It will have the capacity to transport up to 2,600 million cubic feet per day, which represents almost 40 percent of the estimated Mexican national demand in 2016.
Accidents
Gas pipelines carry flammable and volatile material, which is why they are a source of safety concerns.
- June 3, 1989: two moving trains produced sparks that detonated natural gas from a leaking pipeline near Ufa, Russia. There were about 645 dead people.
- 28 September 1993: During the work of placing fiber optics at the Regional Autopista del Centro in Venezuela, the accidental breakage of a main gas pipeline caused an explosion and subsequent fire, leaving 53 people dead and 70 wounds.
- December 28, 1998: explosion of a pipeline in Colombia, in the population of Arroyo de Piedra, where 15 people died and 25 were injured. It was not possible to determine the causes but tests performed by the Colombian authorities indicated the existence of colonies of bacteria, which attacked the pipe causing a localized corrosion and generating a gas leak and an explosion.
- August 19, 2000: the breakage of a natural gas pipeline exploded in flames near Carlsbad, New Mexico killed 12 members of the same family. The cause was an important internal corrosion of the pipeline.
- 30 July 2004: a main pipeline exploded in Ghislenghien, Belgium (treinth kilometres south-west of Brussels), killing at least 23 people and leaving 122 injured, some of which are extremely serious. (Expatica)Filed on 9 February 2007 in Wayback Machine.
- 7 May 2007: an explosion in Ukraine partially destroyed a gas pipeline that transports gas from Russia to the European Union.
Attacks
- September 10, 2007.— Four Mexican oil pipelines (PEMEX) exploded in the early morning in Veracruz, Mexico. These attacks were claimed by the Revolutionary People's Army (PRS).,
Spain
In Spain, in the places through which a gas pipeline passes, the following limitations on property are established:
- Prohibition of performing works of plow or similar to a depth greater than 50 centimeters, as well as planting trees or bushes at a distance less than 2 meters, to count on the axis of the pipe.
- Prohibition of performing any kind of works, construction, building or performing any act that could damage or disrupt the proper functioning of the facilities at a distance less than 10 meters from the axis of the layout, one and the other side. This distance may be reduced if the conditions established by the competent organ of the Administration are expressly requested and met.
- Free access to the necessary personnel and equipment to maintain, repair or renew the facilities with payment, if any, of the damages that occur.
- Possibility to install signaling or demarcation milestones and ventilation tubes, as well as to perform surface or underground works that are necessary for the execution or operation of the facilities.