Gas pipeline laying: methods, equipment, requirements. The gas pipeline security zone

The gas distribution system is a set of interconnected objects, the main purpose of which is to supply "blue fuel" to the consumer. When assembling such networks, of course, all the required technologies must be observed. Laying a gas pipeline is a responsible thing, and you can not neglect safety when doing such work.

The main components of the gas pipeline

Networks designed to transport "blue fuel" include:

• External mains of settlements;
• Means of electrochemical protection;
• Regulatory points;
• Automated control systems;
• Internal highways.

External piping refers to pipes stretched outside buildings, to the case or disconnecting device when entering premises. The internal system is the pipes laid from the external structure to the consumers (plates, boiler). Methods of laying the pipeline can be different.

Types of systems

The main lines intended for the supply of "blue fuel" are classified according to several criteria:

• Type of gas (LPG, natural);
• Number of pressure control stages (single or multi-stage);
• Structures (dead-end, ring, mixed).

In the settlements for the use of the owners of houses and apartments comes mainly natural gas. LPG (liquefied) along the main lines is transported rather seldom. In most cases, it is pumped into cylinders. LPG pipes are supplied only if there is a reservoir or regasification station in the village.

In cities and large settlements, the laying of a multi-stage distribution pipeline is usually carried out. The assembly of a single-stage low pressure is very expensive. And therefore, it is advisable to mount such systems only in small villages. When assembling multi-stage gas pipelines between branches of different pressure, regulatory points are established.

Actions before laying

Before proceeding with the assembly of the gas pipeline:

• Make calculations of the required quantity in a given locality of gas;
• Are determined with the diameter of the pipes;
• Are determined with the need to install automated control systems;
• Make up the project of an external gas pipeline.

The assembly of the internal supply systems of the "blue fuel" is usually the responsibility of the consumers themselves. Connect boilers and cookers under the contract with the owner of the house to licensed companies of the relevant specialization.

Calculation of the required gas

Such planning takes into account:

• Population size and density of construction;
• Absence or presence of hot water supply.

Calculate the estimated maximum gas flow rates. For example, for settlements with the number of people living from 700 to 2000 and a density of building 150-960 m ² / ha, this figure will be equal to 0.7-1.6 m ³ (h · person). In the absence of hot water supply, the estimated maximum flow is reduced by 25%. Perform calculations taking into account the prospects for the development of the town or city for 10 years ahead.

Calculation of pipes

The necessary diameter of the mains of the external gas pipeline is selected, proceeding from:

• The estimated consumption of "blue fuel" during peak hours;
• Pressure losses in the main.

Preliminary calculations of the diameter are performed by the formula

Q ^h(273+t) /P _m v, D = 3.62 * 10 ^-2 √ Q ^{h (273 + t)} / P _m v,

^h - часовой расход при нормальном давлении, P _m - абсолютное давление на участке, v — скорость движения газа. Where Q ^h is the hour flow at normal pressure, P _m is the absolute pressure in the section, and v is the gas velocity.

The resulting results are subsequently adjusted according to the resistance in the pipeline (fittings, connections, turns). To determine the pressure drop, special formulas are used (for each mode of gas supply - its own).

Installation of external gas pipelines: automated control systems

Such equipment is designed to ensure the highest productivity of the mains. Automated control systems (ACS TP RG) have a centralized structure. Their main elements are:

• Controlled points (KP) installed on external roads;
• Central control tower (upper level).
• Gas distribution system (lower level).

The central control room includes several workplaces, united by means of computer networks. The automated control systems of gas pipelines are used:

• With the purpose of operative control of distribution;
• Equipment condition monitoring;
• Accounting for the receipt and consumption of gas.

How can trunk lines

Pull the pipeline is allowed underground or aboveground method. The latest technology is the most economical. The method of laying underground is considered safer at the same time. . This is how the gas pipelines are drawn in the usual way around settlements . However, the implementation of such a technique is more expensive. подобная магистраль получается также более затратной. In service such a line is also more costly.

Some sections of the network in large settlements can be laid above the ground. But they are almost never too long. предусмотрена и на территории промышленных предприятий. The above-ground laying of the gas pipeline is also envisaged in the territory of industrial enterprises.

а чалом монтажа сети в обязательном порядке составляется ее схема. Before the initial installation of the network, its circuit is compulsorily compiled. The highway design, according to the standards, must be carried out in the topographical plan.

Underground gas pipeline laying: rules

: At the site, the gas pipeline is assembled in compliance with the following standards :

• The distance between the pipeline and other surface communications should not be less than 0.2 m;
• In the places of intersection with the communication manifolds, the pipes are stretched in a case;
• Gas mains are laid above other engineering systems;
• Cases outside the intersection are taken out for a distance of at least 2 m;
• The ends of the cases are sealed with waterproofing materials.

олжна составлять по нормативам не менее 0,8 м. Но как правило, траншеи под такие системы выкапывают на один и более метров. The depth of the gas pipeline should be at least 0.8 m in compliance with standards. But as a rule, trenches for such systems are excavated for one or more meters. In any case, the depth of the gasket should be such that the wall temperature of the pipe does not fall below 15 degrees.

Requirements for pipes

Serve "blue fuel" in underground systems can be on steel or polyethylene backbones. т носительно невысокая стоимость. Advantage of the latter is resistance to corrosion and relatively inexpensive cost. применять полиэтиленовые трубы для транспортировки « голубого топлива» нормативы допускают далеко не всегда. However, the use of polyethylene pipes to transport " blue fuel" standards are not always acceptable. прокладка подземных газопроводов с использованием подобного материала невозможна : For example, the laying of underground gas pipelines using such a material is impossible :

• On the territory of settlements with a gas pressure exceeding 0.3 MPa;
• Beyond the territory of settlements at a pressure above 0.6 MPa;
• For the liquid phase of the SGU;
• At a wall temperature of the pipeline below 15 degrees.

The coefficient of strength of pipes used for laying gas external networks should be at least 2.

Pipes made of steel gas can be both seamless and welded. For a subterranean system, such lines with a wall thickness of at least 3 mm can be used. It is allowed to use gas for both gas pipes and spiral seams.

Technology of laying underground highways

Such systems are assembled as follows:

• The marking of the construction strip and the geodesic breakdown of the horizontal and vertical corners of the turns are made;
• Excavating machines with backhoe are excavated;
• Manual completion of the trench;
• The bottom of the trench is leveled;
• Pipes are delivered directly before laying on a site;
• Pipes are inspected for the purpose of detecting defects;
• The whips fall into the trench;
• Welded and joint work is performed;
• Testing of the gas pipeline;
• Work is being done on backfilling the trench.

Prepare the trench for laying the gas pipeline in advance standards are not allowed. No stones and debris on its day should not be. Pipes are welded in lashes outside the trench. This eliminates the possibility of leaks in the future. When lowering the weaves, their impacts on the bottom and the wall must not be allowed.

The assembly of gas pipelines in the winter season of the standard is allowed. However, in this case the trench should be dug up to the unfrozen soil. On the rocky sections, the pipes are laid on a sand cushion. The thickness of the latter should be approximately 200 mm. This avoids the risk of damage to pipes due to contact with stones.

special instructions

Sometimes gas pipelines have to be pulled along problem areas of the terrain. On landslide areas, as well as on soils prone to erosion, the construction of the structure must be made below the limit of possible destruction. Pipes are pulled no less than 0.5 meters from the level of the slide mirror.

Rules for assembling aboveground systems

этого типа предусмотрены следующие : Requirements for laying gas pipelines of this type are provided as follows :

• Above the ground, the gas pipeline should be located not less than 2.2 m in the places where people pass, 5 m above the roads, 7.1 meters above the tram routes, 7.3 meters in the places where the trolley buses go;
• опорами линии должно быть равно максимум 100 м при диаметре трубы до 30 см, 200 м — до 60 см, 300 м — свыше 60 см; The distance between the fixed supports of the line should be a maximum of 100 m with a pipe diameter of up to 30 cm, 200 m - up to 60 cm, 300 m - over 60 cm;
• Pipes made of steel, gas- filled, designed for laying above the ground, should have a wall thickness of at least 2 mm.

The mains of the distribution gas pipeline in small settlements are often laid along the supports. The distance between the latter depends directly on the diameter of the pipes. Thus, for Du-20, this figure will be 2.5 m, Du-50 - 3.5 m, Du-100 - 7 m, etc.

What is the gas pipeline security zone

— сооружения взрывоопасные. Engineering systems of this variety are explosive structures. Therefore, in the immediate vicinity of them, no construction should take place. The dimensions of the security zones depend on the types of gas pipelines:

• High pressure category I (0.6-1.2 MPa) - 10 meters;
• High pressure category II (0.3-0.6 MPa) - 7 m;
• Medium pressure (5-300 MPa) - 4 m;
• Low pressure (up to 5 MPa) - 2 m.

СУГ равна обычно 100 метрам. The security zone of the LPG gas pipeline is usually 100 meters.

According to the regulations, the route is adjusted once a year with the introduction of existing changes in the documentation. In order to mark the protection zone of the gas pipeline, special columns are used. They must be located at a distance of not more than 50 m from each other. Are indicated by the bars and the turn of the road. In the intersections with roads and bridges in the security zone, appropriate warning signs are installed. On the road in such places are also provided signs prohibiting parking.

Laying of gas pipelines inside the premises

In this case, certain safety standards must also be observed. транзитная прокладка газопровода внутри зданий п о внешним поверхностям стен на высоте не менее 1,5 метра от пола. Transit gas pipeline construction inside the buildings and on the external surfaces of the walls at a height of not less than 1.5 meters from the floor. Sometimes the pipes are pulled in canals, covered with shields. The latter, in accordance with the standards, should be easily removable. Through walls or ceilings, gas pipelines are laid in metal, insulated, non-combustible material.

According to the regulations it is forbidden to pull pipes:

• On door and window boxes;
• Transoms;
• Platbands.

Wooden walls before installation of the gas equipment near to them should be isolated asbestos cement sheets. All joints of the internal gas pipeline are welded. Plug-in connections may only be made at the places where the valves are mounted.

For the assembly of internal systems, steel pipes are usually used. But sometimes copper is used for this purpose. It is not allowed to use such lines only for transportation of LPG.

транзитного газопровода к внешнему и его сборка должны по нормативам производиться только специалистами лицензированной компании. The connection of the internal transit gas pipeline to the external one and its assembly must be carried out according to the standards only by the specialists of the licensed company. After the installation of the system, it is tested and accepted with the signing of the relevant document.