To deliver energy thermal resources from generation sources to remote consumers, it is necessary to use special transport networks - heating mains. These are main lines through which, in particular, hot water is transferred in order to ensure the operation of the communal heating system. Despite the massive transition of private homeowners to autonomous hot water systems, heating mains are also used in this area. Installation is carried out according to different schemes - both underground and above it. But the most important thing is compliance with the rules for laying and operating such lines.
Requirements for pipes used
The material of the pipeline must correspond to the temperature loads and pressure in the line. As a minimum, it must maintain performance at 95 °C. Concerningpressure, then for autonomous heating a level of 1.5 atmospheres is considered normative. In the installation of heating mains for heating with such requirements, the following pipes are usually used:
- Steel galvanized. There are practically no temperature restrictions, and the pressure limits are about 12 atmospheres. Mechanical strength and resistance to deformation loads can also be emphasized. However, steel can cause a lot of problems due to threaded connections, not to mention the fact that metal is, in principle, a fairly labor-intensive material in terms of physical handling during laying.
- Polypropylene pipes. There are temperature restrictions (up to 95 ° C), and the maximum pressure is 9 atmospheres. However, the combination of mechanical strength, tightness at the joints and modest weight compensates for these shortcomings.
- Metal-plastic pipes. The optimal solution that stands out for its durability, installation flexibility and practicality. Such pipes for heating mains are used both in industry and in the private sector.
Insulation for heating mains
Even properly selected pipes do not guarantee heat conservation during its transportation. This property depends on the coating of the circuit - a heat insulator. Today, the following materials are used for such purposes:
- Glass wool. It goes well with metal-plastic, has a low density and is cheap. But glass wool can provide effective heat saving only in combination with roofing material or fiberglass. Accordingly, both the costs and the time for installation work increase.
- Bas alt insulator. It has a cylindrical shape, is characterized by ease of installation and high thermal insulation performance. The only negative is that it is expensive in itself.
- Polyurethane foam (PPU). A type of plastic that exhibits resistance to temperature extremes. But the main advantage of this material lies elsewhere. There are practically no restrictions for the installation of PPU heating mains in terms of the complexity of the pipeline. The isolator can even be applied in liquid form, which allows them to spot treat hard-to-reach local areas.
- Cross-linked polyethylene. Polymer-based structural insulator, among the main advantages of which are strength, resistance to thermophysical stress, chemical and mechanical stress.
Technology of installation of heating mains
Organization of the main heat supply system is carried out in several stages:
- Design. Based on the results of a comprehensive survey of the direction of laying the line, taking into account the requirements for the transportation of the coolant, a list of materials, their performance characteristics, as well as the installation configuration are determined.
- Preparing for laying. Technical conditions for the future installation of pipes are being created. The laying area is cleared and, if necessary, trays (channels) are installed for the rear protection of the circuit.
- Installation of pipes. Direct installation of the pipelineheating mains, in which the substrate and insulation material are attached to the prepared trays. Clamps, anodized protection and fixing hardware can be used for this.
- Testing and commissioning in progress.
Heating pipe layout configurations
Several pipelines can be laid in one line. In this regard, one- and two-pipe, as well as a beam method of laying are distinguished. In the first case, only one circuit is used, in the second, two channels, respectively. With radial installation of a heating main, several circuits are connected to a collector, from which flows are directed to individual points of consumption. This system is beneficial in that it allows you to regulate the work of threads, alternately loading and distributing them depending on current needs.
Features of channelless laying
The main difference between this method of organizing heating systems is the rejection of bearing pads. That is, the installation of trays for this type of heating main is not necessary - the installation is carried out directly on the ground. The lack of additional protection and support of the pipeline is compensated by the use of special fittings in polyurethane foam thermal insulation with a polyethylene sheath. Also, for such networks, a system of operational remote control is provided, which continuously monitors the state of the insulation.
Repair of heating mains
Maintenance with diagnostics and repair procedures canbe carried out both in a planned manner according to the schedule, and according to a signal from the control equipment. Repair and restoration operations are performed in the following order:
- Localization of damage using special equipment.
- Dismantling of tray ceilings.
- Dismantling the faulty section.
- Replacement, repair or addition of a problem area with a necessary element. Often, electric welding installation of a heating main is performed at a point with pipe damage in a gaseous environment.
- Cleaning the circuit from dirt and foreign objects.
- Pressure work aimed at checking the tightness after repair.
- Assembling the structure.
Conclusion
Heating mains differ from conventional pipelines in their large diameter and the obligatory ability to serve hot media. This explains the increased requirements for the materials used and the conditions for laying. In the domestic sphere, homeowners are faced with the installation of heating mains when organizing hot water supply. But even in this case, pipes and components of a smaller format are used - with an eyeliner from secondary distribution lines. In terms of technological support, the means of regulation can correspond to industrial networks - at least in terms of functionality. Thermostats, manifold valves, pressure and temperature sensors are also used to control and manage flows.
