Gas pipes: a comparative overview of all types of gas pipes + how to choose the best option
One of the most important issues in autonomous gasification of a house is compliance with fire safety standards and requirements. Even at the design stage, you need to clearly know which pipes for gas are applicable for external and internal installation. A successful combination of their various types will provide maximum reliability of the pipeline.
We will describe how the choice of pipes is made depending on the operational category of the gas pipeline. We will show you which products are used for laying external branches and internal wiring. Based on our recommendations, you can perfectly select the material for the system device and control the work of hired gas workers.
The content of the article:
- The main classification of gas pipelines
- Types of materials for gas pipes
- Characterization and use of steel pipes
- Features of gas pipes made of polyethylene
- Nuances of building a copper gas pipeline
- Conclusions and useful video on the topic
The main classification of gas pipelines
The gas pipeline category, which depends on the gas pressure, is one of the most important criteria that have a significant impact on the choice of pipe material.
There are 5 main categories of the gas network:
- I-A - construction with the highest pressure exceeding 1.2 MPa. The diameter of the pipe is 1000-1200 mm, the purpose is to connect thermal stations, turbines and steam plants.
- I - a system with high pressure in the range of 0.6-1.2 MPa. Its purpose is the transportation of gas and the arrangement of gas distribution points.
- II - pressure is lower than in the previous category, but still considered high. It ranges from 300-600 kPa. The diameter of the pipe is 500-1000 mm, the purpose of the pipeline is to deliver gas from gas distributors to industrial facilities, residential and social buildings.
- III - medium pressure design with indicators of 5-300 kPa. The use of pipes with a diameter of 300-500 mm is allowed.Its purpose is to transport gas from the highway to gas distribution points located near residential buildings.
- IV - a system with a minimum pressure (less than 5 kPa). The diameter of the pipe does not exceed 300 mm, the purpose is to deliver gas from the inlet gas pipeline to residential buildings and directly to the end gas consumption devices.
In addition to the pipeline category and pressure values, an important influence on the choice of pipes is exerted by the features of their laying and operating conditions - external or internal laying, ground or underground.
If they are laid in the ground, then it will be necessary to reckon with such factors as freezing depth, density and thickness of the soil layer, the likelihood of corrosion processes, the presence of stray currents.
To ensure a stable and long-term operation of the gas pipeline, it is necessary to take into account the features of installation and operation at the stage of preparatory and design work, to perform all analyzes that prescribe gasification standards.
Types of materials for gas pipes
The main requirements for a gas transportation system are their fire safety, which is achieved by complete sealing of butt joints. Previously, exclusively steel products were used for the network device, the life of which depended on the thickness of the material and the pressure in the system.
Today, along with steel pipes, industrial products made of copper and polyethylene are very actively used in the creation and arrangement of gas pipelines. The scope directly affects the choice of material.
So, steel pipes are suitable for aboveground and underground gas pipelines. They are successfully used both for house wiring and for creating high-pressure lines. Polyethylene pipes are only suitable for underground installation, while copper pipes are suitable for installing gas systems inside apartments and houses.
To understand which pipes can be used to transport gas, it is necessary to familiarize yourself not only with the norms of the device and gas pipeline design, but also to understand the weaknesses and strengths of each of their materials.
Characterization and use of steel pipes
Currently, steel pipelines are the most common. This is due to the high reliability of the material and a wide range of applications.
General description of steel products
Welded pipes with a spiral or straight seam or seamless hot or cold rolling products meet the requirements of building gasification standards. They are ubiquitous and are used in construction as trunk pipelines so and lines connections to private homes.
For the manufacture of steel pipes used for gasification, low-carbon steel (up to 0.25%) is used. Sulfur (content of not more than 0.056%) and phosphorus (content of not more than 0.046%) are removed from it. This is necessary to give the material the required properties.
The main parameters of the pipes are the thickness of the steel wall and gas pipe diameter, which are determined by calculation and depend on the volume of pumped gas and the pressure in the system.
In addition to the calculated values, the steel pipe must comply with GOST, the main requirements of which are in the following parameters:
- the diameter of the internal gas pipeline should be 25 mm or more;
- pipe diameter for gas distribution systems - 50 mm;
- for the construction of an above-ground gas duct, it is allowed to use a product in the manufacture of which steel 2 mm thick and above is used;
- the thickness of the underground gas duct steel should be at least 3 mm.
In addition to the method of laying the gas pipeline, the diameter and wall thickness of steel products can be influenced by the seismic and climatic features of the territory on which construction is carried out.
Steel pipe marking
Any specialist must understand the marking of pipes, as important information is hidden behind a set of simple letters and numbers. So, the abbreviation VGP means that you have a water and gas pipe, the manufacture of which should be regulated by GOST 3262-75.
The main parameter of the gas pipe is the conditional diameter, marked as DU. For manufactured products with DN 6-150 mm, the standard wall thickness is in the range of 1.8-4 mm. Reinforced pipes are industrially produced. Steel is used for their manufacture, the thickness of which can exceed 5.5 mm.
Marking is present directly on the pipe, the thickness of which is more than 3.5 mm, and the remote control exceeds 159 mm. Otherwise, a package of products is marked on which a label is posted containing information about the length and diameter, grade of steel used. Be sure to label the manufacturer’s OTC mark.
The letters in the marking of steel pipes correspond to the following parameters:
- P - steel of high accuracy;
- N - the presence of knurled threads;
- P - the presence of chopped threads;
- D - elongated thread;
- M - coupling equipment.
The standard length of steel pipes VGP is 4-12 m. They are called dimensional. With a length of more than 12 m they are called unmeasured.
Features of steel pipelines
Thin-walled lightweight steel pipes are used exclusively in low pressure gas ducts, which are used in gasification of private houses and in the construction of intra-apartment wiring. The light weight of the material makes it easier to work with pipes and allows you to easily lay a network, characterized by complex structural features.
Light products can be bent at a slight angle without resorting to a pipe bender. Pipes made of steel with thin walls are characterized by high thermal conductivity, which often leads to the formation of condensate.
It is possible to avoid premature aging as a result of corrosion if, after installation of the pipeline, their surface is treated with oil paint. The more layers it is applied, the more effective the steel protection will be. Such products can easily be connected by soldering, and threaded connections using fittings are also allowed.
If necessary, the installation of a gas duct that can withstand the highest pressure, it is customary to use more massive thick-walled reinforced pipes. The highest strength of the gas pipeline is achieved with high-quality joining of seamless steel pipes by welding, at the final stage, the control of joints is mandatory.
Advantages and disadvantages of designs
Steel products, due to their physical qualities, are characterized by high strength, and high-quality welding work ensures reliability and tightness of the seam. They can be considered universal due to the ability to perform ground and underground styling. They are also suitable for both indoor and outdoor use.
Along with the positive aspects, there are also a number of disadvantages that cannot be ignored when choosing pipes and taking measures to optimize the service life of steel gas ducts:
- the complexity of the installation work;
- low corrosion resistance;
- a tendency to form condensate, especially actively manifested in light pipes;
- high mass;
- high cost;
- poor flexibility.
Subject to construction standards, installation rules, operation and ensuring high-quality insulation, the uninterrupted operation of a steel gas pipeline will be at least four decades.
Features of gas pipes made of polyethylene
Along with steel structures, other products have recently been actively used, for the manufacture of which polymeric materials are used.
Installation work on the installation of a polyethylene gas pipeline is carried out much faster than in the case of steel pipes, which is explained by the absence of threaded connections and the need to use heavy electric and gas welding equipment.
Methods of joining polymer structures
Today, the quality of polyethylene pipes makes it possible to build reliable underground gas pipelines, whose service life reaches 80-90 years. Most often, a network of polyethylene materials is arranged to lead the line to private houses.
In addition, such products can be used to transport gas in systems whose pressure does not exceed 1.2 MPa.
The tightness of the connection of polyethylene pipes of proper quality is ensured by welding, which can be performed in two ways:
- Pipes, the edges of which are preheated with a special soldering iron, are mounted end-to-end. Similarly, fittings are installed. Warming up must be carried out until viscosity is achieved.
- The edges of the product are inserted into a special coupling, inside of which there are heating elements. The applied voltage ensures the heating of the elements and the fixing of the pipes in the fitting. The joint obtained by electrofusion welding withstands pressure up to 16 MPa.
If you decide on the individual connection to the gas network, then it is better to prefer a cheaper installation option, which assumes butt welding.
With the collective gasification of cottage villages, summer cottages, villages, it is better to resort to more expensive electrofusion welding of polyethylene elements of the gas pipeline. This method provides maximum tightness and reliability of the connection.
Characteristics of polyethylene pipes
Pipes made of polyethylene are produced with a diameter of 20 to 400 mm, standard sizes are marked SDR11 and SDR17.6. Depending on the strength class, products with the marking PE80 (black with yellow inserts) and PE100 (black with blue inserts) are distinguished.
PE80 polyethylene pipes are suitable for individual gasification and arrangement of a low pressure pipeline. In turn, PE100 products have higher strength, and they can be used to create gas ducts with a pressure of up to 1.2 MPa.
It should be noted that the installation of PE100 pipes will require a lot of effort, since they will have to be heated to a higher temperature, however, these costs are compensated by the excellent quality of the connection.
Advantages and disadvantages of gas polymer pipes
The previously popular steel pipe rolling is noticeably superseded by polyethylene analogues.
There are many reasonable explanations for this fact, which lie in the useful qualities of PE pipes:
- Good corrosion resistance, ability to withstand the effects of chemically aggressive compounds.
- High strength, resistance to mechanical stress.
- Excellent throughput with no roughness.If we compare polyethylene products with steel of the same diameter, the throughput of the gas duct from PE pipes will be 30% higher.
- Ease of installation work. PET welding does not require heavy gas and electric welding equipment, as when installing a steel gas pipeline. In addition, pipes made of polyethylene are easily bent, which allows you to bypass the obstacle arising in the way of the gas pipeline.
- Low cost of polyethylene products in comparison with similar ones made of copper and steel.
Polyethylene pipes are quite actively used in connecting gas to a private house. This is due to a number of positive qualities. However, there are some features in their application that limit or even completely exclude the possibility of building a gas network from polyethylene structures.
So, you can’t use PET in seismic active zones, in areas where the temperature drops to -45 degrees, in gas pipelines with a pressure of more than 1.2 MPa.
In addition, polyethylene pipes are completely incompatible with the laying of networks in tunnels and sewers, while steel ones allow this option. It must be taken into account that when polyethylene is heated to 80 degrees, it deforms with subsequent destruction.
It is not recommended to use PET to create ground-based gas ducts, since the material is rapidly destroyed under the influence of ultraviolet radiation. If a decision is made on the installation of an onshore pipeline, then the pipes must be coated with a special protective polymer composition.
Nuances of building a copper gas pipeline
Copper pipes have recently begun to be used for the construction of a gas network. Drawn and cold rolled are allowed. copper pipes with a wall thickness of at least 1 mm for internal wiring.
Copper is a rather expensive material, however, its use is justified by the simplicity of installation work and the ability to create lines of complex configuration.
Another indisputable fact in favor of copper pipes is their attractive appearance. Since the gas pipeline cannot be hidden in niches of walls and ducts, steel structures can easily spoil the appearance of the room, while copper pipes only enrich the interior.
Copper products have the following positive qualities, which may be decisive when choosing them for a gas duct device:
- high ductility, due to which it is possible to lay lines of complex configuration;
- simplicity and ease of installation, the product is easy to cut, the pipes are connected by using press fittings or soldering;
- attractive appearance;
- durability - the service life, subject to technology, reaches 100 years;
- resistance to mechanical damage and resistance to the effects of chemically active compounds.
Copper pipes have their own weaknesses, the main of which is high thermal conductivity, which contributes to the formation of condensate. And also their strength is much lower than steel, and the price is much higher.
With the technology of soldering copper pipes, providing a tight connection, will introduce next articlewhich we recommend reading.
Conclusions and useful video on the topic
The video demonstrates the process of manufacturing seamless steel pipes:
Electrofusion welding of polyethylene pipes in the video:
Currently, copper and polymer pipes, although in some cases capable of competing with steel pipes, cannot fully replace them. Polyethylene constructions are ideally suited for underground gas pipelines, copper ones make installation of internal wiring easier, and steel ones are universal and can be used to create any type of gas network.
Do you have any valuable advice on choosing gas pipes? Want to tell us how you arranged the gas supply in your house? Please write comments, post a photo on the topic, ask questions in the block below.