Today they are used for heating different materials. One of them is polyurethane foam. Its popularity is growing. But like any material, it can be damaged. The UEC system for polyurethane foam pipes comes to the rescue. It controls the insulating layer of the pipeline. Thanks to the UEC, you can prevent pipe damage by taking timely measures. This reduces repair time and costs.
UEC system: purpose, operating principle, damage correction
What is ODC? This is a system of operational remote control. Performs constant and continuous monitoring of (PPU). Monitoring is carried out throughout the service life of the heating main.
The system is designed to detect defects such as:
- damage to the pipe itself;
- damage to the polyethylene wrapping that wraps the pipe and the thermal insulation layer;
- damage to signal wires;
- the process of connecting signal wires to a pipe;
- poor butt connection of wires.
The principle of operation of the UEC is based on a sensor that monitors the insulation layer, namely its humidity, which runs along the entire length of the pipeline. At least two wires are located in a layer of thermal insulation and connected along the entire length of the pipeline. At the starting and ending points they are connected into one loop. The loop consists of signal wires made of copper. Between steel pipes and a polyurethane foam layer of thermal insulation, a sensor is formed to control the level of humidity of the thermal insulation.
Sensor tasks:
- control of the entire length of the sensor and control of the length of the signal loop. Identification of the length of the pipeline section that is covered by the sensor;
- moisture control of the thermal insulation layer;
- searching for the place where the thermal insulation layer has become wet or the signal wire has broken.
The sensor's job is to provide accurate data on the moisture content of the insulation. When the amount of moisture in the thermal insulation layer increases, this means that it can be either a coolant leak from the pipe or moisture from outside. Once this happens, the sensor reports by reflecting the pulse.
The principle of recognizing the damaged area and eliminating it:
- As soon as the thermal insulation is broken, the sensor reports this. It remains to find the damage in the area that is located between the signal indicators;
- the selected area is disconnected from the UEC system;
- overlaying data on the joint diagram;
- Based on the data obtained, the required section of the pipeline is dug up and repairs are made.
PPU pipes - a new and promising development
The question remains, what is PPU? It's quite simple. These are polyurethane foams - a universal group of polymers. The material is new, but has already gained its popularity.
The Russian climate forces us to heat our homes. And the pressing question is not how to bring heat into the house, but how to bring it with the least loss. Previously, the pipeline was wrapped in glass wool, secured with steel wire, and covered with galvanized steel sheets on top. The material is valuable, so it did not last long on the pipes. Today, polyurethane foam pipes are increasingly used. Thermal insulation is also made from it.
Advantages of PPU:
Stages of installation of polyurethane foam pipes:
- stripping;
- welding and quality control;
- for this purpose a flaw detector is needed;
- putting on the coupling. It is poured under it polyurethane foam. The coupling heats up and settles. This allows for a tight connection.
The UEC system for the heating main is an additional method of protection. And it lies in preventing major emergencies and eliminating small damage as quickly as possible.
The UEC system: what does it consist of?
Built-in copper wire. It is a conductor through which a signal about damage is transmitted. It is located in a heat-insulating layer of polyurethane foam. Without it, the UEC system will not work.
There are two types of wire:
- basic. It follows the contour of the pipeline and stretches along the entire path of the heating main;
- transit. Designed to form a signal loop and runs along the shortest path between the start and end points of the heat pipe.
Instruments for monitoring and measurement:
- damage detectors. They monitor the break or short circuit of the built-in signal wire. They do not establish the cause of the damage, but state a fact. A stationary detector (220 V) provides constant monitoring, a portable detector (9 V) provides periodic monitoring. The first option can monitor from one to four pipelines. Has an alarm system. The second option works autonomously, powered by a battery. Capable of servicing an unlimited number of pipelines. They are installed at control points using a switch terminal;
- pulse reflectometer. Capable of not only recording damage, but also finding its location. Does not provide information about the causes of the defect. It is connected at the factory and before installation to the ends of the pipes in those places where the signal wires extend beyond the insulation. It is also connected during control, directly during operation of the heating main.
The switch terminal of the UEC system is presented as an intermediate link between the control devices and the pipe. Usually they are placed at a distance of 300 meters from each other. They are used for connecting control devices, as well as switching signal wires.
UEC system project - how it happens
The UEC system for polyurethane foam pipes is designed with the ability to connect with existing heating mains, as well as with pipelines that are just being planned.
One of the two signal wires is marked (also known as the main wire). Located to the right in the direction of water movement to its destination. The location of the conductor from the surface of the pipe ranges from 10 cm to 25 cm.
The resistance indicator must meet certain requirements:
- for signal wires per meter of length, the resistance should range from 0.012 Ohm to 0.015 Ohm;
- for PPU insulation per 300 meters of pipe length - 1 Ohm.
For various conditions During operation, various switching terminals are used. The classification depends on different conditions.
Weather:
- measuring instruments are used only in dry and ventilated conditions;
- sealed. Applicable subject to high humidity air.
Territorial:
- end, used at the end points of control;
- unifying. It is used at the points of connection of some sections of the heating main;
- combining with the ability to access stationary detectors;
- passable. In those places where a rupture of the insulating layer was recorded;
- intermediate. It is installed at control points where the lateral branch of the heating main begins, as well as at intermediate control points.
The maximum length of the heating main for the UEC project is calculated by determining the maximum coverage area of the monitoring devices.
The above-mentioned sensors are selected depending on the availability of 220 V in the designed area where the use of UEC systems is planned:
- if 220 V is present, a stationary detector is used.
- in the absence of the necessary resistance, a portable one is used.
What devices will be installed and their quantity depends on the length of the heating main section. If the length of the planned heating main is longer than that allowed for the detector to operate, this section of the heating main is divided into smaller sections. Separate control systems are used for them.
The control points provided by the project are intended to allow operating personnel access to the signal conductors. The points should not be further than 300 meters from each other.
The terminals are installed into the carpet at the end points. Their installation is also possible in central heating points.
ICC "Technology" offers modern operational remote control for leaks in pipelines - UEC.
If, after laying a pipeline or during operation of a heating network, a water leak appears at any joint (welding point), its presence is detected by determining the reduced resistance between signal wires laid in polyurethane foam (PPU insulation).
- Broken copper signal conductors;
- Wetting of the thermal insulation layer of polyurethane foam (due to a leak in either the metal pipe or the outer polyethylene shell).
- Detect a defect without disrupting the operating mode of the heating network.
- Remember and store measurement results.
Diagnostics of heating network pipelines
Most of the heating networks in Russia are significantly worn out. This is due to active corrosion of the outer surface steel pipeline. According to the data given in the article “Ways to reduce accident rates at thermal and engineering networks enterprises", the corrosion rate in some sections of the heating pipeline reaches values above 1 mm/year. This leads to failure of individual sections of the heating pipeline within 5...7 years after the start of its operation.
Currently, for laying pipelines of heating networks, pipes that are previously thermally waterproofed with polyurethane foam (PPU insulation) are becoming increasingly widespread.
Such pipes are produced with certain construction lengths and have signal lines inside the insulating layer covering the pipe.
When laying, the pipes are welded, and the corresponding signal wires from adjacent pipes are connected to each other (Fig. 1). Pipe welding areas are isolated.
Fig. 1 An example of the formation of a signaling line from the conductors of an installed pipeline.
If, after laying a pipeline or during operation of a heating network, a water leak appears at any joint (welding point), its presence is detected by determining the reduced resistance between the signal wires, since the insulation between the signal wires gets wet. For this purpose, a stationary damage detector “Pikkon” is used (Fig. 2).
The specific location of wetness is determined using the device "Portable digital reflectometer REIS-105M" or "Digital reflectometer REIS-205".
The UEC system allows you to detect the following types of defects:
- breakage of copper signal conductors;
- getting the thermal insulation layer of polyurethane foam wet (due to a leak in either the metal pipe or the outer polyethylene shell);
- Detect a defect without disrupting the operating mode of the heating network;
- Remember and store measurement results;
- Exchange information with a personal computer.
Based on the results of measurements on pipelines, a report is drawn up, which indicates the diagram of pipeline joints and pulse reflectometry data, which can be used to accurately determine the specific location where the insulation is wet. The use of the UEC system makes it possible to create a computer database in order to determine the dynamics of the development of insulation defects and signal control systems.
Installation of conductors at the factory
Before manufacturing the PI pipe at the factory, between the polyethylene protective sheath and metal pipe two copper signal wires configured in a certain way are fixed. The conductors must have the necessary pretension.
Installation of conductors during construction.
1 - fastening tape;
2- crimp sleeve;
3- wire holder;
4- polyurethane foam insulation;
5- metal pipe;
6 - signal conductors;
7 - polyethylene insulation.
Detector Features
A stationary detector allows for constant monitoring of the condition of pipelines. The detector is installed permanently and only on one object. The detector operates from an alternating current source of 220 Volts. Detectors can monitor from one to four pipelines simultaneously at one site independent systems control.
Fig.2 Stationary damage detector “Pikkon”
The detector is installed at a control point, which must be provided for and indicated in the design of the UEC system.
At the control point, the detector is connected to the signal conductors using special switching terminals of the “KT14” or “KT15” brand - for a four-channel and two-channel detector, respectively.
An example of calculating the cost of a UEC system for a pipeline.
Initial data
1. The pipeline diagram is shown in Appendix No. 1.
3. The diagram of the UEC system is shown in Appendix No. 2.
2. Heat supply system 2 pipes (n = 2).
Solution
1. Selection of monitoring devices
1.1 Determination of the type of control devices.
From the above pipeline diagram we see that the designed pipeline enters the central heating station. The central heating center has the ability to supply 220V power, therefore, for monitoring it is necessary to use a stationary two-channel damage detector "PIKCON" DPS2A.
1.2. Determination of the number of devices.
For a stationary detector, according to the passport data, the maximum length of the controlled pipeline is equal to one channel: L max. = 2500 meters.
The length of the projected section is equal to: L pr. = 600+300+500+400+300 = 2100 m meters.
Since L max. > L ave., then for a given route one stationary detector is sufficient.
2. Determining the location of control points
2.1. In point 1, it is planned to connect a stationary damage detector there.
2.2. After 300 meters from the camp. 1
2.3. At a side branch
2.4. Because 2
2.5. After 200 meters from the camp. 2
2.6. Because 3
2.7. Because 4
2.9. After 250 meters from the camp.
3. Equipping control points with elements of the control system.
| Feature point | Element of the UEC system | Qty | Unit Change |
| 1 | Stationary damage detector “PIKKON” DPS-2AM | 1 | PC. |
| Switching terminal “KT15” | 1 | PC. | |
| Pulse reflectometer "Flight-105M" | 1 | PC. | |
| Copper wire MM 1.5 | 4200 | M | |
| 2 | Ground carpet | 1 | PC. |
| 1 | PC. | ||
| 2 | PC. | ||
| 3 | Ground carpet | 1 | PC. |
| Intermediate terminal “KT12/Sh” | 1 | PC. | |
| Cable extension kit “KUK5” | 2 | PC. | |
| 4 | Ground carpet | 1 | PC. |
| 1 | PC. | ||
| Cable extension kit “KUK5” | 2 | PC. | |
| 5 | Ground carpet | 1 | PC. |
| Intermediate terminal “KT12/Sh” | 1 | PC. | |
| Cable extension kit “KUK5” | 2 | PC. | |
| 6 | Ground carpet | 1 | PC. |
| Connecting terminal “KT15/Sh” | 1 | PC. | |
| Cable extension kit “KUK5” | 2 | PC. | |
| 7 | Ground carpet | 1 | PC. |
| Intermediate terminal “KT12/Sh” | 1 | PC. | |
| Cable extension kit “KUK5” | 2 | PC. | |
| 8 | Ground carpet | 1 | PC. |
| Intermediate terminal “KT12/Sh” | 1 | PC. | |
| Cable extension kit “KUK5” | 2 | PC. | |
| 9 | Ground carpet | 1 | PC. |
| End terminal "KT-11" | 1 | PC. | |
| Cable extension kit “KUK5” | 2 | PC. |
The exact cost of the work is determined according to the technical specifications provided by the customer within two working days.
The ODC (operational remote control) system is used to detect mechanical or chemical (caused by corrosion) damage to isothermal pipelines laid by air or underground. Today it has become widespread, being used as part of pipelines itself. for various purposes(including utilities).
TO important features UEC systems should include:
- high level of automation of the damage search process;
- its continuity;
- accuracy of detection of damage locations;
- reliability and security of the system from failures under any operating conditions;
- relatively low cost of system components;
- ease of use.
The purpose of using the UEC system is:
- detection of depressurization points in the serviced pipeline;
- detection of places of depressurization of its outer shell.
In addition, the UEC system is capable of identifying its own faults, including
- violation of the integrity of detector conductors;
- poor butt connection of detector conductors;
- short circuit of detector conductors to the pipe.
ODK system: principle of operation
The operating principle of the UEC system is based on the fundamentals of pulse reflectometry technology. In accordance with it, the indicator conductor acts as a pulse emitter, the pipe and outer shell act as reflectors, and the heat-insulating layer acts as a medium with certain wave properties. It is on the constancy of these properties that the operation of the mechanism is based.
If the thermal insulation layer gets wet, its wave properties change towards a decrease in resistance and, as a result, an increase in conductivity. This is immediately detected by special control and measuring instruments that combine the functions of a reflectometer and a megger.
An increase in the humidity of a heat-insulating layer installed in accordance with all the rules of an isothermal pipeline can be caused either by damage to the pipe and leakage of the medium transmitted through it, or by damage to the outer shell and the ingress of moisture from atmospheric air (or, alternatively, soil). In any case, repairs are needed.
Modern UEC systems have several stages of operation. This makes it possible not only to detect the fact of depressurization and establish its location, but also to determine the extent of possible damage. The detection accuracy is very high, and the probability of error is zero.
UEC system: equipment composition
The standard UEC system has three technological levels
- conductor-detectors from copper wire(wire cross-section diameter 1.5 mm) with output cables;
- switching terminals for connecting control and measuring instruments installed in carpets (special metal safe-type boxes, which are available in wall-mounted and ground-mounted versions);
- stationary or mobile instrumentation, also called “damage locators”.
The structure of the UEC system is universal. This makes it possible to easily expand and rebuild it, providing the most complete and most effective monitoring possible technical condition pipeline communications.
The procedure for using the UEC system is extremely simple. It includes the following technical actions:
- checking the readiness of the instrument and the integrity of the wiring network (self-monitoring);
- data collection;
- saving data for further analysis.
The frequency of control activities using the UEC system is not regulated by law and is established by operating organizations on an individual basis.
