Gas installation

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A gas installation is understood as the installation of pipelines (with fittings), gas devices that convey or consume gas. This includes laying the gas pipes, installing valves and, if it is a highly flammable gas such as natural gas or propane , safety valves with non-return valves , as well as installing gas appliances such as a gas-powered instantaneous water heater .

Furthermore, the installation of an exhaust system including condensation water disposal and the securing of the combustion air supply for the gas devices.

A gas detector is at least common, particularly in vehicles with a closed cabin .

At the transition from the incoming gas supply (e.g. of a house) to the gas installation, there are pressure regulators and gas measuring devices, commonly known as gas meters , which measure the volume taken.

If the gas supply does not come from an incoming line, it can come from the following sources:

  • Pressure vessels
    • Gas bottles, kettles; with or without liquid phase; with very different operating pressures,
  • (almost) pressureless containers (such as cryogenic kettles for liquefied air gases; collecting bubbles for expensive gases such as helium; piston syringes and plastic bags on a laboratory scale); gasometer
  • Gas generators
  • Geological sources
    • Cased borehole to a natural gas storage facility or to an outgassing covered landfill

All such sources of gases need a well-ventilated gas storage room or box that is locked to unauthorized persons, but accessible to the fire brigade, without fire-promoting material and with sufficient opportunities to relax outdoors; a fume cupboard in the laboratory. Flammable gases need an explosion- proof environment.

Gas meters in buildings (Germany)

Gas meters must be installed easily accessible in a dry place, which is determined by the network operator in accordance with the Low Pressure Connection Ordinance (NDAV) together with the type of meter location. From building class 3, gas meters may not be installed in necessary stairwells or their exits to the outside. Gas meters must not be an obstacle in hallways that serve as escape routes. The installation room must be ventilated through at least one upper and one lower opening, each with a 5 cm² free cross-section. A shut-off device must be provided in front of the gas meter. Connection pieces of dismantled gas meters must be closed on all sides.

Gas pipes in buildings (Germany)

Inside buildings, gas pipes can be made of galvanized threaded pipe , precision steel pipe ( carbon steel or stainless steel ) or copper pipe . Multi-layer composite pipes may also be used up to a pressure of 100 hPa . If the pressure is higher, metallic lines may no longer be laid under plaster . Otherwise, it can be laid exposed or in shafts or channels.

In the case of metal pipes, the load-bearing parts of the pipe supports must be made of non-combustible material. In the case of brazed copper pipes, this also applies to the dowels used. Since multi-layer composite pipes are not resistant to higher temperatures (HTB) anyway, protection against escaping gas is guaranteed in this case by using thermal shut-off devices (TAE).

Consistently without pipe connections routed gas lines (z. B. of corrugated pipe or multilayer pipe ) may run in the cavities, such as shafts, channels, suspended ceilings or drywall. In the case of multi-layer composite pipes, this only applies if no fire zones are exceeded. The integration of device connections or gas sockets is possible.

Gas lines with pipe connections may be laid in cavities that are either ventilated through ventilation openings with a free cross section of at least 10 cm² each or filled with a "suitable filler material that is dimensionally stable and tight" so that no gas can accumulate. Alternatively, the line can be laid in a corrosion-resistant casing pipe that is open at least at one end.

Gas pipes may not run in elevator or ventilation shafts, ventilation pipes, garbage disposal systems and chimneys or be embedded in chimney chimneys, provided they are still used as such or the commissioning is possible again at any time.

Gas pipes may be laid in escape routes from buildings up to building class 2. From building class 3, escape routes must be made of non-combustible building materials. Flammable coatings up to 0.5 mm thick are permitted. In accordance with DIN 4102-4, installation ducts and shafts in these escape routes must be at least fire-retardant (F-30) throughout and consist of non-combustible building materials. In the necessary stairwells and adjoining rooms on the way outside, installation ducts and shafts may have to be made fire-resistant (F-90); Necessary ventilation openings must not be arranged here. Alternatively, cables may be laid under plaster, free of voids, with an overlap of at least 15 mm on a non-combustible plaster base or comparable protection. Flammable pipe coatings up to 2 mm thick are permitted under plaster. The line may also be laid freely in necessary corridors. In principle, no gas pipes may be laid in the safety stairwells and their exits.

If gas lines cross movement joints, they must be laid in corrosion-resistant protective pipes made of steel or other measures must be taken to prevent the introduction of movement stresses into the pipeline. If the fire resistance is required, the gap to the protective pipe is filled at least 40 mm deep on both sides with high-temperature-resistant mineral wool or foaming material . In the case of composite pipes, a fire bulkhead or a fire-resistant installation duct must be used instead .

Multi-layer composite pipe can be laid in recesses in the raw ceiling or in leveling layers for impact sound insulation or screed , but not in the screed itself. From building class 3, exposed or concealed multi-layer composite pipes may not be installed in escape routes (necessary stairwells and corridors).

In buildings from building class 3, cables made of composite pipes that penetrate walls and ceilings with requirements for fire resistance must be provided with approved bulkheads or run in a fire-resistant installation duct or shaft. In the case of metal lines up to 160 mm in diameter, a continuous sheathing made of high-temperature-resistant mineral wool is sufficient, provided that the duct is closed so that it is smoke-tight. In all cases, the fire protection regulations in the building regulations and the pipeline system directive must be observed.

Dimensioning of the pipeline system according to TRGI 2018

The TRGI contains tables and diagrams for the simple dimensioning of gas lines made of steel or copper pipes. The manufacturer's tables and diagrams are to be used for composite pipes and special fittings. It is assumed that the pressure at the house connection or behind the pressure regulator is 23 hectopascals (hPA) or millibars . At least 20 millibars should be available on each gas appliance. The difference of 3 millibars corresponds with 300 Pa to the pressure loss within the gas distribution network, which must not be exceeded when designing the pipeline system. In addition to pipe length and diameter, the pressure losses from bends, branching T-pieces ("current separation") and fittings are taken into account. In the case of metal pipes, the pressure losses from bent pipe sections, connecting sleeves, reducers, tier bends and T-pieces in the passage are neglected. In the case of plastic pipes, the manufacturer's information on pressure loss in connection sleeves and T-pieces must also be taken into account in the passage.

The `` diagram method '' is suitable for measuring the maximum length of individual feed lines that consist of one pipe material throughout. A maximum pressure loss of 300 Pa is specified, as is the nominal size of the gas flow monitor , gas meter and device connection fitting . The gas meter is loaded with a maximum of 80% of its intended maximum flow. The diagrams envisage the use of copper, stainless steel, medium-weight threaded or corrugated pipes and a maximum load of 110 kW. In the TRGI of 2008 was u. a. include an "exemplary dimensioning diagram" for PE-X pipes. Otherwise, these diagrams are provided by the manufacturer of the pipe system.

The diagram method is based on the assumption that only a single gas appliance is supplied by the house connection, often a gas boiler . First of all, the length of the pipeline between the main shut-off device (HEA) and the gas appliance, as well as the number of 90 ° angles in the line, must be determined. For every 90 ° angle in pipes up to a nominal size of DN 28, the actual pipe length 30 cm is added; 50 cm for DN 32 and 70 cm for DN 40 are added. (No statement is made on 45 ° angles. Occasionally, it is suggested to add half the value for 45 ° angles.) If an additional corner shut-off device is provided after the gas meter, add 3 m to the line length. All other angles and bends on the gas meter as well as within the gas appliance were taken into account when setting up the diagrams.) With the total line length (the "calculated length ") in meters and the nominal load of the gas appliance, the maximum line length can be determined from the diagrams depending on the The nominal diameter of the pipeline can be determined. Depending on the nominal diameter of the gas meter and the gas flow monitor, as well as depending on the type and nominal diameter of the valve at the gas appliance (either angle type (E), straight through (D)), or alternatively, when using a safety gas outlet (GSD) is in each case a different curve on the graph to choose. When using type M (GS M) gas flow monitors, the line length must be limited by short horizontal lines on the diagram. A Type K flow switch should be used above these lines. The pressure gain in rising lines is not taken into account in the diagram method.

Pipe systems with branches, with more than one connection, with reduced pipe diameters in the course of the pipe or made of different pipe materials are to be dimensioned according to the `` table method ''. In coordination with the network operator, a total pressure loss other than 300 Pa can be provided. Up to three 90 ° bends required for mounting the gas meter as well as its inlet-side shut-off valve are included in the pressure loss tables.

General recommendations for the design of the system

The house connection line to the gas pressure regulator can be provided with a load of up to 200 kW with DN 25 and up to 500 kW with DN 32. From the house connection, the pipe diameter should not increase in the direction of flow. Gas stoves can be assumed with a nominal load of 9 kW and gas stoves, gas grills, patio heaters and gas lanterns with 13 kW. Gas instant water heaters are often assumed to have 23 kW.

If it turns out during the design that the total pressure loss exceeds 300 Pa, the pipe section with the greatest pipe pressure gradient R should be enlarged first. Device connection fittings should generally have the same or the next smaller nominal diameter of the supply line. In the latter case, if the total pressure loss of 300 Pa is exceeded, a larger connection fitting must first be selected. When selecting, the minimum nominal size according to table L.0 and the pressure loss according to table L.3 must also be observed.

Since natural gas is lighter than air, there is a pressure gain in the case of height differences in the pipe system. If risers are selected so that the pipe pressure gradient R remains below 5 Pa per meter, the pipe length can be disregarded, since the pressure loss in the pipe is compensated for by the pressure gain due to the height difference. The inlet pressure is then (approximately) the same at all connections of the riser.

The pressure loss between the house connection and the risers should be less than 70 Pa.

Sequence of fittings

Gas filters should only be installed before the gas pressure regulator or after the device connection fittings (probably to make the pressure losses calculable and to simplify the dimensioning of the system).

Grandfathering

The adaptation of a gas system to the current guidelines is necessary in the event of "significant changes" to the system. This includes neither maintenance work nor tests, changing the gas meter or replacing a gas device. However, if the new gas device is installed at a different location and a change in the routing becomes necessary, the existing protection expires and the installation of gas flow monitors and thermal shut-off devices may become necessary.

Guidelines

Please note the following when installing gas:

  • Model guideline on fire protection requirements for piping systems (MLAR) - contains u. a. Image examples for the production of fire protection seals for gas pipes. The first version from 1988 was still abbreviated as "MRbAaLeit".

literature

  • Andreas Braun, Stefan Gralapp, Jürgen Klement, Holger Schröder, Kai-Uwe Schuhmann: Gas installation in practice. The commentary on the technical rule for gas installations DVGW-TRGI 2018, DVGW reference book series Praxis, 2018, ISBN 978-3-8955-4218-3 .
  • Heinz Lüdke: Gas supply from A to Z. German publishing house for basic industry, 1963.

Web links

Footnotes

  1. ↑ Worksheet G 600 (A), Technical Rule for Gas Installations ( TRGI ) of the DVGW , Section 5.5, September 2018
  2. ↑ in some sources seamlessly drawn threaded pipe is required
  3. ↑ Worksheet G 600 (A), Technical Rule for Gas Installations ( TRGI ) of the DVGW , Sections 5.3.4.1 and 5.3.5.6, September 2018
  4. ↑ Worksheet G 600 (A), Technical Rules for Gas Installations ( TRGI ) of the DVGW , Sections 5.3.4.2 and 5.3.5.1f, September 2018
  5. ↑ a b Worksheet G 600 (A), Technical Rule for Gas Installations ( TRGI ) of the DVGW , Sections 5.3.4.3 and 5.3.5.7, September 2018
  6. ↑ Worksheet G 600 (A), Technical Rule for Gas Installations ( TRGI ) of the DVGW , Sections 5.3.4.3 and 5.3.5.7, September 2018
  7. ↑ Worksheet G 600 (A), Technical Rule for Gas Installations ( TRGI ) of the DVGW , Sections 5.3.4.6.1 and 5.3.5.12, September 2018
  8. ↑ Worksheet G 600 (A), Technical Rule for Gas Installations ( TRGI ) of the DVGW , Sections 5.3.4.5 and 5.3.5.9, September 2018
  9. ↑ Worksheet G 600 (A), Technical Rules for Gas Installations ( TRGI ) of the DVGW , Section 5.3.5.10, September 2018
  10. ↑ Worksheet G 600 (A), Technical Rule for Gas Installations ( TRGI ) of the DVGW , Section 5.3.5.12, September 2018
  11. ↑ Worksheet G 600 (A), Technical Rule for Gas Installations ( TRGI ) of the DVGW , Sections 5.3.4.6 and 5.3.5.12, September 2018
  12. ↑ a b c Worksheet G 600 (A), Technical Rule for Gas Installations ( TRGI ) of the DVGW , Section 7.1, September 2018
  13. ↑ Günter Cerbe, Benno Lendt: Fundamentals of Gas Technology: Gas Procurement - gas distribution - gas use , page 513, Carl Hanser Verlag GmbH & Co KG, November 7, 2016
  14. ↑ Günter Cerbe, Benno Lendt: Fundamentals of Gas Technology: Gas Procurement - gas distribution - gas use , page 529, Carl Hanser Verlag GmbH & Co KG, November 7, 2016
  15. ↑ Worksheet G 600 (A), Technical Rule for Gas Installations ( TRGI ) of the DVGW , Section 7.4, September 2018
  16. ↑ Günter Cerbe, Benno Lendt: Fundamentals of Gas Technology: Gas Procurement - gas distribution - gas use , page 530, Carl Hanser Verlag GmbH & Co KG, November 7, 2016
  17. ↑ Worksheet G 600 (A), Technical Rule for Gas Installations ( TRGI ) of the DVGW , Section 7.3.4, September 2018
  18. ↑ a b c d Worksheet G 600 (A), Technical Rule for Gas Installations ( TRGI ) of the DVGW , Section 7.3.5, September 2018
  19. ↑ Worksheet G 600 (A), Technical Rule for Gas Installations ( TRGI ) of the DVGW , Section 7.2.1, September 2018
  20. ↑ Dipl.-Ing. Jörg Schütz: Gas flow monitor - one year of practical experience , inventory protection - practical problems and remedies - changes to the installation guidelines, IKZ-HAUSTECHNIK, edition 01/02/2005, page 28 ff. In: IKZ.de
  21. ↑ DIBt : Model guideline on fire protection requirements for pipe systems (Edition 2 of October 11, 2016) (PDF; 507 kB)
  22. ↑ Sample guidelines on fire protection requirements for piping systems (MRbAaLei), (PDF document) version September 1988, point 2.4 "Piping systems for flammable liquids and flammable or oxidizing gases". In: Bauministerkonferenz.de