Natural gas pipeline

This article or the following section is not adequately provided with supporting documents ( e.g. individual evidence ). Information without sufficient evidence could be removed soon. Please help Wikipedia by researching the information and including good evidence.

This article covers public utility lines and gas pipelines. For gas pipes in buildings and on individual properties, see gas installation .

Marking of a gas pipeline in the forest near Darmstadt

Natural gas pipelines are pipes or pipelines that are used to transport natural gas (and other fuel gases ) and distribute them to various consumers.

construction

Natural gas pipeline in the arid region of Antofagasta, Chile

As a rule, they are made of metal or plastics (mostly HDPE , less often PVC ), can be hundreds to thousands of kilometers long for international energy transports and were mostly characterized by the color rapeseed yellow (RAL 1021) until 2007. The new color for gas pipes is signal yellow ( RAL 1003 ) according to DIN 2403 .

The supply of municipalities and city districts is provided by underground lines that measure up to a few decimetres clear width and are laid below the frost line. On the other hand, pipes in private households usually only have nominal widths between ¹ ⁄ ₂ and 2 inches (= DN 15–50 mm).

Cable diameter class	Nominal size DN
A.	${\displaystyle x\geq 1000{\text{ mm}}}$
B.	${\displaystyle 700{\text{ mm}}\leq x<1000{\text{ mm}}}$
C.	${\displaystyle 500{\text{ mm}}\leq x<700{\text{ mm}}}$
D.	${\displaystyle 350{\text{ mm}}\leq x<500{\text{ mm}}}$
E.	${\displaystyle 225{\text{ mm}}\leq x<350{\text{ mm}}}$
F.	${\displaystyle 110{\text{ mm}}\leq x<225{\text{ mm}}}$
G	${\displaystyle x<110{\text{ mm}}}$

Large pipelines often run in two or more strings. Nord Stream in the Baltic Sea has two parallel pipes with an internal diameter of 1153 mm, two further parallel strings for Nord Stream 2 have a similar diameter, and the Nabucco pipeline was planned with a diameter of 1220 mm. South Stream through the Black Sea was planned in 2014 with an outer diameter of 813 mm and a wall thickness of 39 mm at a depth of up to 2200 m. The EUGAL project from 2017 with predominantly two strings on the 485 km long route from Lubmin to Deutschneudorf provides for pipe diameters of 1420 mm. The Power of Sibiria pipeline should also have a diameter of 1,420 mm, a distance of 3,000 km and a pressure of 98 bar. The 1804 km long Trans-Anatolian Gas Pipeline (TANAP) will have 1420 mm and 1220 mm diameter pipes on land, but 915 mm in the Sea of ​​Marmara .

The overpressure in gas lines is between 200 bar in high-pressure transport lines, over 800 millibars in medium-pressure lines, down to 50 and 20 millibars in streets or house connections . Depending on the supply area, house connections are also operated with medium pressure; here there is a pressure reducer inside the building that lowers the increased street-side pressure to the level required in the building. Long sea crossings typically have higher feed pressures, while compressor stations are built on land at shorter intervals.

Gas lines with the smallest diameters in the millimeter range supply the pilot flame in boilers or small appliances in laboratories. They are protected against extinguishing of the pilot flame by thermocouples or other valves, which has been increasingly monitored by electronics for about ten years.

A number of non-detachable and detachable connections for gas pipes are permitted. See also pipe connection # gas lines

Each gas pipeline is divided into individual sections, the connecting nodes of which have technical facilities for operational safety and maintenance of the pipeline.

Depending on the dimension of the pipeline, the latter devices consist of simple gas slides , larger shut-off valves or, in the case of cross-border natural gas lines, of complete cooling, heating and pumping stations . One of the first gas pipelines equipped in this way was the southern European Trans Adriatic Pipeline .

Supplied pressure levels:

• High pressure (> 1 to 4 bar, 16 bar)
• Medium pressure (> 100 mbar to ≤ 1 bar)
• Low pressure (≤ 100 mbar)

safety

In the 1970s, most consumer networks were converted from town gas to the non-toxic natural gas . It is provided with odorous substances ( odorization ) in order to smell an uncontrolled discharge. In this way, a rough check can also be made as to whether the house lines are tight. Odorisation can be detected with the nose from a concentration of around 300 ppm, which is far below the lower explosion limit.

A serious disadvantage of natural gas, however, is its dry consistency, which means that older pipes become leaky because the sealing hemp dries out on the threaded connections. The "long sleeves" previously used are particularly susceptible to this. This led to tree damage in urban areas during the conversion period. Regular inspections of galvanized steel gas pipes in the house installation are therefore recommended in order to detect leaks at an early stage. However, the gas lines in the house installation are almost exclusively laid in copper or NiRo steel and fittings sealed with O-rings are pressed, so that the likelihood of leaks is very low. Before that, pipes in houses with a 1–2 inch diameter were carried out in “black” iron pipes, oxy-fuel welded, which, however, required high craftsmanship. Much earlier, leads made of lead were also common, which had the great advantage of being easy to bend and lay. But since the soft material could easily be damaged, they were banned as early as the first half of the 20th century.

Gas and power lines laid underground must be laid with a minimum clearance for safety reasons. This can be fallen short of if electrical insulation and explosion-proof ventilation is guaranteed. On one rare occasion, damage to an underground cable triggered an electric arc that damaged a plastic natural gas pipeline, ultimately leading to a gas explosion . Since then, an extra insulating layer has been mandatory when natural gas and power lines intersect in the ground. Gas pipes laid underground made of steel are provided with a protective jacket made of polyethylene to protect them against the damp environment of the ground . This is to prevent rust formation and the associated weakening of the pipe material. Gas lines with increased protection requirements, such as high-pressure gas lines, are additionally secured using cathodic protective measures.

Capture

Underground gas pipelines are increasingly being recorded in a special pipeline register in which all maintenance and construction companies must enter their data. Therefore, in a few years' time, the public networks will be almost completely covered, while the private feed lines are subject to official inspection anyway.

The line cadastre is usually kept by the municipality, in the wider area by the federal state. In addition to the most important data on the respective line, it also contains its position coordinates and the mean laying depth. Cables of all kinds are increasingly being laid in shared cable ducts in order to enable damage to be repaired more quickly. In addition, the gas pipes have been marked with yellow bands for a long time in order to indicate the critical depth to the excavator operator when excavating.

See also

• List of natural gas pipelines
• pipeline
• Trigger (line)

Web links

Wiktionary: Natural gas pipeline  - explanations of meanings, word origins, synonyms, translations

Footnotes

1. ↑ Impetus for the German economy: South Stream and EUROPIPE sign major order europipe.com, January 29, 2014, accessed May 15, 2019.
2. ↑ EUROPIPE delivers 635,000 tons of large-diameter pipes for the EUGAL pipeline europipe.com, April 3, 2017, accessed May 15, 2019.
3. ↑ Power of Sibiria: Largest gas transport system in Eastern Russia gazprom.de, accessed May 15, 2019.
4. ↑ Trans Anatolian Natural Gas Pipeline (TANAP) socarmidstream.az, accessed May 15, 2019.
5. ↑ Knut Håkansson: Lexicon of gas installation: (Gas installation from A - Z) , p. 284 ff., Vulkan-Verlag, 1996.