The development of industry and modern urban economy is completely impossible without the use of pipelines for various purposes. Uninterrupted operation of heating systems for water supply, sewage, gas, oil pipelines, etc. can be ensured only subject to the observance of the established technologies and standards during their installation. There are many ways to assemble pipelines.
What technologies can be used
The following basic piping methods are available:
- An open method involves the assembly of highways on supports, as well as in impassable and passage collectors.
- Closed or trenchless method. It involves laying pipelines underground without first digging the ground.
- The hidden way. In this case, the pipes stretch along the dug trenches.
To assemble highways, depending on the characteristics of the transported medium, installation methods and external conditions, pipes made of different materials can be used: concrete, metal, plastic, ceramic, asbestos. In cities, the laying of water supply pipelines can be carried out in the same trench with other communications (heating mains, cable systems, etc.). In this case, the use of both trench and channel technology is allowed.
Features of an open method of laying pipelines
Using this technique, heating, water supply, sewage, and other pipelines can be laid. The use of non-passable channels under the mains in comparison with the trench method has one undeniable advantage. The pipes laid in them are not subjected to soil pressure during heaving or moving, and therefore, they last longer. The disadvantage of this methodology is considered to be difficult access to highways if they need to be repaired.
Piping in the passageways is more expensive. However, in this case, the specialists of the service companies have the opportunity to access the highways without the need for earthwork.
Above the surface of the earth, pipes are usually laid only in undeveloped areas of settlements, as temporary highways, etc. Various types of concrete and metal structures, overpasses, walls of structures, etc. can serve as supports for them.
Ways to lay pipelines in cities can be different. But in any case, the highways through settlements are pulled out of the pressure zone in the ground from structures and buildings. This helps preserve the foundations in the event of a breakthrough. All underground urban utilities are divided into three large groups: trunk, transit and distribution. The first variety includes all the main communication networks of the village. Transit pipelines pass through the city, but are not used in any way. Distribution called highways, departing from the main directly to the buildings.
Hidden laying method
Pipeline construction using this technique is most often carried out. The main advantage of laying pipes in trenches is its relative cheapness. However, the assembly technology in this case must be strictly observed. After all, access to pipes in this case is difficult and it is necessary to ensure that repair of the pipeline is required as little as possible.
Rules for work with hidden laying
Trenches under the trunk can be used shallow or deep. In the first case, the pipeline is laid at 50-90 cm. When using the deep method, trenches are dug below the freezing of the soil. The industrial pipeline can be laid at a depth of up to 5 m. The rules for laying highways are observed:
- If the soil is dense, pipes are laid directly on it.
- When laying at a depth of more than 4 m, or if the pipes are made of not too strong material, they arrange an artificial substrate. The same is done on condition of the assembly of highways in difficult hydrogeological conditions.
- The bottom of the trenches is prepared so that the pipes come into contact with it throughout. Existing voids are covered with local soil or sand.
- If there is groundwater in the lowest places, pits are arranged for their pumping.
Hidden laying method: technology features
The technology for assembling highways is selected, including depending on which pipes of which material are used. Polymer welded several pieces (up to a length of 18-24 m) directly near the storage facility, and then delivered to the place of laying. Here in the summer time they are collected in a continuous string, after which they are placed in a trench. Installation is carried out using mobile welding units. In winter, the pipes are laid in a trench one at a time and connected by gluing or using rubber rings.
The construction of ceramic pipelines on a slope is made from top to bottom. Before installation, pipes are inspected for chips. They are connected by the bell method with compaction with a bitumen strand and a cement mortar lock device. Concrete pipes are laid in approximately the same way. In this case, a rubber ring can be used as a sealant.
Asbestos cement pipelines with a pressure of up to 0.6 MPa are assembled using double-breasted asbestos cement couplings, and with a pressure of up to 0.9 MPa - using cast-iron flanged ones. Non-pressure pipelines are made using cylindrical couplings. Steel lines are laid using welding.
Trenchless method
Pipeline laying in this way is mainly used when it is impossible to assemble using hidden technology. For example, this is exactly how highways are pulled under busy highways, railways, external utilities, etc. There are the following methods for trenchless pipe laying:
- a puncture;
- punching;
- horizontal drilling;
- shield penetration.
Puncture method
According to this technology, main pipelines are pulled on loamy and clay soils. When using it, it is possible to lay pipelines up to 60 m long. This technique consists in the following:
- a steel tip is put on the pipe;
- at a certain distance from the obstacle, dig a pit and install a hydraulic jack on it on supports;
- a pipe is lowered into the pit with a pipe of a smaller diameter inserted into it - a “ramrod”;
- a gradual puncture of the soil is performed.
Using this technique, the earth cannot be pulled out. In the process of puncture, it is simply compacted around the circumference of the pipe.
Punching method and shield penetration technology
These technologies are also quite often used when it is necessary to assemble pipelines under obstacles. Laying the pipeline by the method of punching allows you to overcome obstacles up to a hundred meters long. In this case, the pipe is pressed open into the ground with its open end. An earthen plug formed in the process is removed.
The driving shield consists of a support, a knife and a tail. The second provides cutting of the rock and deepening the structure into an array. The supporting part has the form of a ring and is designed to give the structure the necessary rigidity. In the tail section is a control panel shield.
Directional horizontal drilling
This method is considered the most costly. But he has one definite advantage. Using this technology, even the most dense soils can be penetrated. In this case, drilling is carried out by special rods connected by hinges. Driving can be carried out at a speed of 1.5-19 m / h. Unfortunately, this technology cannot be used if there is groundwater on the site.
Thus, the choice of pipelining methodology depends on the characteristics of the soil, the material used to make the pipes, and production needs. In any case, the technology for assembling highways must be followed exactly. A high-quality pipeline is a guarantee of uninterrupted operation of industrial enterprises and urban utilities.