Gas pipes: a comparative review of all types of gas pipes + how to choose the best option

One of the most important issues during autonomous gasification of a home is compliance with fire safety standards and requirements.Even at the design stage, you need to clearly know which gas pipes are suitable for external and internal installation. A successful combination of their different types will ensure maximum reliability of the pipeline.

We will tell you how to select pipes depending on the operational category of the gas pipeline. We will tell you which products are used for laying external branches and internal wiring. Taking into account our recommendations, you will be able to ideally select the material for the installation of the system and monitor the work of hired gas workers.

Main classification of gas pipelines

The category of a gas pipeline, depending on the gas pressure, is one of the most important criteria that has a significant impact on the choice of pipe material.

There are 5 main categories of gas network:

1. I-A - design 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.
2. I - system with high pressure, ranging from 0.6-1.2 MPa. Its purpose is to transport gas and arrange gas distribution points.
3. II - pressure is lower than in the previous category, but is still considered high.It fluctuates in the range of 300-600 kPa. The diameter of the pipe is 500-1000 mm, the purpose of the gas pipeline is to deliver gas from gas distributors to industrial facilities, residential and social buildings.
4. III - medium pressure design with values ​​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 pipeline to gas distribution points, which are located near residential buildings.
5. IV - system with minimal 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 final gas consumption devices.

In addition to the gas 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 installation, above-ground or underground.

If they are laid in the ground, then you will have to take into account such factors as the depth of freezing, the density and thickness of the soil layer, the likelihood of corrosion processes, and the presence of stray currents.

A ground or air gas pipeline is characterized by ease of installation work to create it, but additional care is required for reliable operation

To ensure stable and long-lasting 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, and perform all the analyzes that require gasification standards.

Types of materials for gas pipes

The main requirements for the gas transportation system are their fire safety, which is achieved by completely sealing the butt joints.Previously, exclusively steel products were used to construct the network, the service 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 choice of material is directly influenced by the area of ​​application.

Thus, steel pipes are suitable for above-ground and underground gas pipelines. They are successfully used both for intra-house wiring and for creating high-pressure lines. Polyethylene pipes are suitable only for underground installation, and copper pipes are suitable for installing gas systems inside apartments and houses.

Polyethylene gas pipelines are successfully replacing steel underground structures for similar purposes due to ease of installation, durability and lower cost.

To figure out which pipes can be used to transport gas, you need to familiarize yourself not only with the design standards and gas pipeline design, but also to understand the strengths and weaknesses of each of their materials.

Characteristics and use of steel pipes

Nowadays, steel gas 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

The requirements of gasification building codes are met by welded pipes with a spiral or straight seam or seamless hot or cold rolled products. They are ubiquitous and are used in construction as main pipelines so and lines connections to private houses.

For the manufacture of steel pipes used for gasification, low-carbon steel (up to 0.25%) is used. Sulfur (content no more than 0.056%) and phosphorus (content no more than 0.046%) are removed from it. This is necessary to give the material the required properties.

The main parameters of pipes are the thickness of the steel wall and gas pipeline diameter, which are determined by calculation and depend on the volume of pumped gas and pressure in the system.

Seamless steel pipes are most often used for high-pressure gas pipelines, this is due to the maximum tightness of the joints that are obtained during the joining process

In addition to the calculated values, rolled steel pipes must comply with GOST, the main requirements of which are the following parameters:

• the diameter of the internal gas pipeline must be 25 mm or more;
• pipe diameter for installing gas distribution systems - 50 mm;
• for the construction of an above-ground gas duct, it is permissible to use a product in the manufacture of which steel with a thickness of 2 mm or higher is used;
• The thickness of the steel of the underground gas pipeline must 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 seismic and climatic features of the territory where construction is taking place.

Marking of steel pipes

Any specialist must understand pipe markings, since behind a set of simple letters and numbers lies important information. So, the abbreviation VGP means that in front of you is a water and gas pipe, the manufacture of which must be regulated by GOST 3262-75.

The main parameter of a gas pipe is the nominal diameter, marked as DN.For manufactured products with a diameter of 6-150 mm, the standard wall thickness is in the range of 1.8-4 mm. Reinforced pipes are produced industrially. For their manufacture, steel is used, the thickness of which can exceed 5.5 mm.

A package of steel pipes with a diameter of less than 159 mm is marked with a label, after reading which you can find out the full characteristics of the product

The marking is present directly on the pipe, the thickness of which is more than 3.5 mm, and the DN exceeds 159 mm. Otherwise, a package of products is marked, on which a label is posted containing information about the length and diameter, and the grade of steel used. The manufacturer's quality control mark must be present on the label.

The letters in the marking of steel pipes correspond to the following parameters:

• P – high precision steel;
• N – presence of rolled thread;
• P – presence of cut thread;
• D – extended thread;
• M – equipped with a coupling.

The standard length of VGP steel pipes is 4-12 m. They are called dimensional. With a length of more than 12 m they are called unmeasured.

Features of steel gas pipelines

Thin-walled lightweight steel pipes are used exclusively in low-pressure gas pipelines, which are used in gasification of private houses and in the construction of intra-apartment wiring. The low weight of the material makes it easier to work with pipes and allows you to easily lay a network characterized by complex structural features.

Lightweight products can be bent at a slight angle without using a pipe bender. Steel pipes with thin walls have high thermal conductivity, which often leads to the formation of condensation.

Premature aging as a result of corrosion can be avoided if, after installing the pipeline, their surface is treated with oil paint. The more layers of it are applied, the more effective the protection of the steel will be. Such products can be easily connected by soldering, and threaded connections using fittings are also allowed.

A threaded connection is the most vulnerable point of a gas pipeline; it is best to use flax fiber for sealing, and after installation, check the tightness of the connection by applying a soap solution to the joint

If it is necessary to install a gas pipeline that can withstand the highest possible pressure, it is customary to use more massive, thick-walled, reinforced pipes. The highest strength of a gas pipeline is achieved with high-quality connection of seamless steel pipes by welding; at the final stage, control of the connections is required.

Advantages and disadvantages of designs

Steel products, due to their physical properties, are characterized by high strength, and high-quality welding work ensures the reliability and tightness of the seam. They can be considered universal due to the ability to perform above-ground and underground installation. And 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 pipelines:

• complexity of installation work;
• low corrosion resistance;
• tendency to form condensation, which is especially active in light pipes;
• high weight;
• high cost;
• poor flexibility.

If construction standards, installation and operation rules are observed, and high-quality insulation is ensured, the time of uninterrupted operation of a steel gas pipeline will be at least four decades.

Features of polyethylene gas pipes

Along with steel structures, other products for the manufacture of which polymer materials are used have recently been actively used.

Installation work on 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 for joining polymer structures

Today, the quality of polyethylene pipes makes it possible to install reliable underground gas pipelines, the service life of which reaches 80-90 years. Most often, a network of polyethylene materials is installed to connect the line to private houses.

In addition, such products can be used for gas transportation in systems whose pressure does not exceed 1.2 MPa.

To connect polyethylene pipes end-to-end, you need to carefully center them, heat the edges until melting and connect under pressure, which is set on an adjustable centralizer

The tightness of the connection of polyethylene pipes of proper quality is ensured by welding, which can be performed in two ways:

1. Pipes, the edges of which are preheated with a special soldering iron, are mounted end-to-end. Installation of fittings occurs in a similar way. Warming up must be carried out until viscosity is achieved.
2. The edges of the product are inserted into a special coupling, inside of which there are heating elements.The applied voltage ensures heating of the elements and fixation of the pipes in the fitting. The joint obtained using electrofusion welding can withstand pressures of up to 16 MPa.

If the issue of an individual connection to the gas network is being decided, then it is better to prefer a cheaper installation option that involves butt welding.

When collectively gasifying cottage communities, dacha communities, and villages, it is better to resort to more expensive electrofusion welding of polyethylene gas pipeline elements. This method ensures maximum tightness and reliability of the connection.

Characteristics of polyethylene pipes

Polyethylene pipes are produced with diameters from 20 to 400 mm, standard sizes are marked SDR11 and SDR17.6. Depending on the strength class, there are products marked PE80 (black with yellow inserts) and PE100 (black with blue inserts).

The PE-80 polyethylene pipe is marked with a characteristic blue line and is used for constructing an underground low-pressure gas pipeline

PE80 polyethylene pipes are suitable for individual gasification and low-pressure pipeline installation. In turn, PE100 products have higher strength and can be used to create gas pipelines with pressures up to 1.2 MPa.

It should be taken into account that the installation of PE100 pipes will require great 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 products are being noticeably replaced by polyethylene analogues.

There are many reasonable explanations for this fact, which lie in the beneficial qualities of PE pipes:

1. Good corrosion resistance, ability to withstand exposure to chemically aggressive compounds.
2. High strength, resistance to mechanical stress.
3. Excellent throughput, ensured by the absence of roughness. If we compare polyethylene products with steel products of the same diameter, then the throughput of a gas pipeline made of PE pipes will be 30% higher.
4. Ease of installation work. Welding PET does not require heavy gas and electric welding equipment, as when installing a steel gas pipeline. In addition, polyethylene pipes bend easily, which allows you to bypass obstacles that arise along the path of the gas pipeline.
5. 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 of their use that limit or even completely eliminate the possibility of constructing a gas network from polyethylene structures.

Thus, PET cannot be used in seismic active zones, in areas where there is a decrease in temperature to -45 degrees, in gas pipelines with a pressure of more than 1.2 MPa.

In addition, polyethylene pipes are completely incompatible with laying networks in tunnels and collectors, while steel pipes allow this option. It should be taken into account that when polyethylene is heated to 80 degrees, it deforms and subsequently breaks down.

The use of PET for creating above-ground gas pipelines is not recommended, since the material quickly degrades under the influence of ultraviolet radiation.If a decision is made to install an above-ground pipeline, then the pipes must be coated with a special protective polymer composition.

Nuances of constructing a copper gas pipeline

Copper pipes relatively recently began to be used for the installation of gas networks. It is allowed to use drawn and cold-rolled 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 ease of installation work and the ability to create lines of complex configurations.

Properly connected copper pipes not only ensure complete tightness of the joints, but also fit perfectly into the interior of any room

Another indisputable fact in favor of copper pipes is their attractive appearance. Since the gas pipeline cannot be hidden in niches in walls and ducts, steel structures can easily spoil the appearance of the room, while copper pipes will only enrich the interior.

Copper products have the following positive qualities, which may be decisive when choosing them for a gas duct installation:

• high plasticity, which makes it possible to lay lines of complex configurations;
• simplicity and ease of installation work, the product is easy to cut, pipes are connected by using press fittings or soldering;
• attractive appearance;
• durability - service life, subject to technology, reaches 100 years;
• resistance to mechanical damage and resistance to the effects of chemically active compounds.

Copper pipes also have their weaknesses, the main one of which is high thermal conductivity, which contributes to the formation of condensation.And also their strength is much lower than steel, and the price is much higher.

He will familiarize himself with the technology of soldering copper pipes, which ensures a hermetic connection. next article, which we recommend reading.

Conclusions and useful video on the topic

The video demonstrates the manufacturing process of seamless steel pipes:

Electrofusion welding of polyethylene pipes in the video:

At present, although copper and polymer pipes are capable of competing with steel pipes in some cases, they cannot completely replace them. Polyethylene structures are ideal for underground gas pipelines, copper structures facilitate the installation of internal wiring, and steel ones are universal and can be used to create any type of gas network.

Do you have valuable advice regarding the selection of gas pipes? Would you like to tell us how you installed the gas supply in your home? Please write comments, post photos on the topic, ask questions in the block below.