The presence of the UEC system on PPU pipelines makes it possible to determine with high accuracy the places of moisture penetration into the pipeline (the occurrence of damage or defects in the polyethylene sheath, welded and butt joints), prevent accidents and reduce repair costs to a minimum. Accuracy in determining the place of moistening of thermal insulation made of polyurethane foam allows you to carry out repair and restoration work quickly, efficiently and with minimal involvement of material and human resources.

Absence of the system of ODK of PPU pipelines at channelless laying entails the impossibility timely detection corrosion of the full section of the pipeline, which is contrary to the requirements safe operation thermal networks.

The cost of equipping the pipeline with devices of the UEC system is no more than 0.5 - 2% of the cost of the facility.

The ODK system consists of:

• built-in copper wire(control conductor) in advance insulated pipes and pipeline elements in PPU insulation,
• components, shaped products for connecting equipment elements,
• measuring equipment for continuous monitoring of controlled pipeline system,
• outline diagram of the entire signaling system,
• a project with documentation on control conductors built into a specific signaling system.

The composition of the instrumental part of the UEC system:

• Terminals (connectors) for connecting control devices. Connectors are usually placed at a distance of 300 meters from each other,
• Cables for connecting signal conductors to terminals in control points,
• Stationary or portable detectors (stationary 220 V or portable 9 V), fixing changes in the humidity of the heat-insulating layer. The detector allows you to simultaneously control two pipelines up to 5 km long each,
• Damage locator (pulse reflectometer) that determines the type and location of a pipeline malfunction or breakage of a signal conductor with an accuracy of several meters,
• Insulation tester.

Principles of operation of the ODK system.

The UEC system provides high precision determination of wet areas of insulation, which cannot be achieved by methods based on the measurement of active resistance. Monitoring the state of the UEC system during the operation of pipelines is carried out using a device called a detector. This device captures electrical conductivity thermal insulation layer. When water enters the heat-insulating layer, its conductivity increases, and this is recorded by the detector.

One detector allows you to simultaneously control two pipes up to 5 kilometers long each (two lines of conductors of 10 km each). The detectors can be powered from a 220 volt mains supply or from an independent 9 volt power source (standard batteries), which eliminates the need for laying separate power lines.

When using a stationary detector, it is possible to organize a centralized control of the state of the UEC system of an extensive heating network of considerable length (up to 5 km) from a single control room. To do this, the stationary detector has contacts with galvanic isolation for each channel, which are closed in the event of a malfunction.

Used to locate damage portable device, called a locator. As a locator in the UEC system of STS Izolyatsia, a pulse reflectometer is used, which ensures high measurement accuracy.

One locator allows you to determine the location of damage at a distance of up to 2 kilometers from the point of its connection. Due to the fact that the measurement accuracy of the locator is 1% of the length of the measured line, it is advisable to locate the locator connection points at a distance of no more than 300-400 meters from each other in order to fix the damage location more accurately. To obtain more accurate measurements, these distances must be reduced accordingly.

With the help of STS Izolyatsia locators, it is possible to determine several humidification points from one terminal. The connection of the detector and the locator to the conductors of the UEC system, as well as the necessary switching, is carried out using special connectors called terminals. Terminals are installed in ground or wall carpet.

The terminals are sealed and do not require additional power supply. To simplify switching and measurements, according to the requirements of operating organizations, plug-in connectors are used. Terminals are connected to conductors using flexible cables. The delivery set includes two types of cables: for connecting terminals at intermediate points along pipelines (5-core cable) and for connecting terminals at the end sections of the heating main (3-core cable). To measure the parameters of the UEC system (insulation resistance and resistance of signal conductors) during the period of work on the insulation of joints, adjustment and commissioning of the control system, an insulation tester is used that provides insulation control during high voltage(250V and 500V).

Measurement at a voltage of 500 V is carried out only for individual elements pipelines during the installation of the heating system. For inspection of installed heating mains, only 250 V voltage should be used.

LIST OF MAIN EQUIPMENT FOR INSTALLATION OF THE UEC SYSTEM

Purpose and main technical characteristics

Switching terminals are an intermediate link between the pipeline and the control device.

Terminals are intended for connection of control devices and switching of signal conductors.

Depending on the functions performed, the terminals differ in design and have different designations:

Designation	Purpose
CT-11	Connection to the UEC system of portable damage detectors. Connection to the UEC system of pulsed reflectometers. Additionally, the terminal performs the function of the "KT-13" terminal, i.e. loops the signal wires. Loopback is performed outside the terminal.
KT-12/Sh	Separation of the UEC system at intermediate points of control. Connection of the UEC system at intermediate points of control. Connecting a portable fault detector and an impulse reflectometer.
CT-13	Loopback of the UEC system. Connection of impulse reflectometers.
KT-14	Connection to the UEC system of a stationary four-channel detector. Connection to the control system of a stackable connecting cable - for a four-pipe system. Connection of four independent systems JDC converging from different sides into one thermal camera or other similar object or diverging into four different sides from one object.
KT-15	Connection to the UEC system of a stationary two-channel damage detector. Connecting a pulse reflectometer. The connection of two disparate parts of one system from one project. Loopback of the UEC system at the end sections - for a four-pipe system.
KT-15/Sh	Connecting a pulse reflectometer. Connecting a portable fault detector. It performs the same function as "KT-11", but only for four pipes at the same time. Separation of the UEC system into independent sections. Connection of two independent systems of ODK from different projects. Connection of two disparate parts of one system from one project (in the case when the system is separated into parts by pipes or valves not insulated with polyurethane foam). Connection to the control system with a stackable connecting cable. Loopback of the UEC system at the end sections. Performs the same function as "KT-13", but only for four pipes at the same time.
KT-16	Connection of three independent UEC systems converging in one thermal chamber (or other similar object). Connection to the UEC system of a pulsed reflectometer.

Damage detector determines the type and presence of pipeline defects. The detector does not determine the location of the defect.

Detector brand	Name
DPP-A	Portable damage detector
DPP-AM	Portable multi-level damage detector
DPS-2A	Fault detector stationary two-channel
DPS-2AM	Fault detector stationary two-channel multilevel
DPS-4A	Fault detector stationary four-channel
DPS-4AM	Fault detector stationary four-channel multilevel

Locator - pulse reflectometer "Flight - 105R"

Pulse reflectometer is designed to determine the location of defects on pipelines in polyurethane foam insulation with a system of operational remote control(ODK).

Defined defects:

• Insulation wetting (fistula, damage to the membrane).
• Breakage of the conductors of the signaling system of the UEC.
• closure signal wire on the pipe.

Distinctive features:

• Compactness.
• Menu in Russian.
• Large memory capacity (up to 200 traces)
• Comes with software.
• Transported in a shoulder bag.
• The cost is lower than foreign analogues.

Instrument capabilities:

• Determination of defects at an early stage of their development - before the operation of damage detectors.
• Detection of defects without disturbing the operation of the heating system.
• Memorization and storage of measurement results.
• Exchange of information with a personal computer.

Specifications:

• insulation resistance;
• conductor resistance.

Used for:

StroyMetService carries out adjustment, repair and also delivery to MIPC (for heating mains under construction in Moscow) with UEC.

UEC system is designed for continuous or periodic monitoring of the moisture content of the heat-insulating layer and the integrity of the wires of the UEC system. It ensures the absence external corrosion steel pipeline, guaranteeing safe and long-term operation.

UEC system is an obligatory element (included in GOST 30732-2006) of pipelines in polyurethane foam insulation.

UEC system at a cost of only 0.5-2% of total cost object depending on the volume of the order. One device (portable detector) can control several objects. The specialists of our company carry out the adjustment of the UEC system of any kind of complexity.

The system includes:

• signal copper conductors embedded in all elements of the heating network,
• terminals (connectors) along the route and at control points (central heating, boiler room, carpet),
• control devices: portable (mobile) for periodic and stationary for continuous control,
• devices for determining the exact location of damage or leakage-locators (reflectometers).

All necessary elements we complete as soon as possible.

The system is based on measuring the conductivity of the thermal insulation layer, which changes with changes in humidity. To search for fault points (wetting of PPU insulation, breaks in signal conductors), methods and devices based on pulsed reflectometry are used.

Virtues this method is its applicability for a wide range of moisture insulation and the ability to search for breaks in signal conductors in several places. Before carrying out work on the adjustment of the SODK, the customer provides an approved wiring diagram and the project of the reconstructed heating main.

The article will tell you how the UEC system works in PI pipes and how to do it correctly. The information is useful for those who want to save money and do the installation themselves, and for those who already have experience in using such a heating system, but the remote control is out of order or of poor quality.

Ignorance of the basic principles of operation, incorrect installation of elements and inability to handle devices often lead to the fact that all good things are considered useless or useless. This happened with the system of operational remote control of heating networks: the idea was excellent, but the implementation, as always, let us down. The indifference of the customer, on the one hand, and the “responsible” work of the builders, on the other hand, have led to the fact that in our country, the SODK works correctly at best in 50% of the constructed pipelines, and it is used in 20% of organizations. Taking Europe as an example, even not far away, let's say Poland, one can see that the incorrect operation of the remote control system is equated to an accident on a pipeline with urgent repair work. In our country, you can much more often see a street dug out in the middle of winter in search of a place for a heat pipe break than summer ones. preventive work electrical teams. In order to make things clear, let's look at the SODK in heating networks from the very beginning.

Purpose

Pipelines of heating networks from generation to generation remain steel, and the main reason for their destruction is corrosion. It occurs due to contact with moisture, and the outer wall is more susceptible to rust. metal pipe. The main function of the SODK is to control the dryness of the pipeline insulation. Moreover, the reason is indicated without distinction as the ingress of moisture from the outside due to a defect in the plastic pipe-shell, and the ingress of coolant on the insulation as a result of a defect in the steel heat pipe.

With help special tool and SODK can be defined:

• wetting of insulation;
• distance to wet insulation;
• direct contact of the SODK wire and a metal pipe;
• cliff wires SODK;
• violation of the insulating layer of the connecting cable.

Principle of operation

The system is based on the property of water to increase conductivity electric current. Used as insulation in PI pipes, polyurethane foam in the dry state has a huge resistance, which electricians characterize as infinitely large. When moisture enters the foam, the conductivity instantly improves, and devices connected to the system record a decrease in insulation resistance.

Areas of use

It makes sense to use pipelines equipped with an operational remote control system for any underground laying. Quite often, even knowing that the pipeline has a defect and there are significant losses of the coolant, it is almost impossible to determine the location of the gust visually. It is precisely because of this that winter period you either have to dig the whole street in search of a leak, or wait until the water itself washes its way out. The second option quite often ends in news bulletins with notes that cars, people or anything else that had the misfortune to be nearby failed in the city of N due to an accident on heating networks and a collapse of the earth's surface.

Does not add information content and the presence of the pipeline in the channel. Due to steam, it is not always possible to determine the point of leakage and excavation will still be significant and long. The only exception, perhaps, are large passage tunnels with communications, but they are rarely built and are very expensive.

The option of air laying of pipelines is the place where the UEC system does not make any practical sense. All leaks are visible to the naked eye and waste for additional control is useless.

Structure and structure

PI pipes used in heating networks consist of steel pipe, shell pipes made of polyethylene and foamed polyurethane as insulation. This foam contains 3 copper conductors with a cross section of 1.5 mm 2 s resistivity from 0.012 to 0.015 Ohm/m. The wires located in the upper part are assembled into a circuit, in the position “without 10 minutes 2 hours”, the third one remains unused. The signal or main conductor is considered to be located to the right in the direction of the coolant. It enters all branches and it is by it that the condition of the pipes is determined. The left conductor is transit, its main function is to create a loop.

Connecting cables are used to extend cable outlets and connect pipelines to switching points. Usually 3 or 5 cores with the same cross section of 1.5 mm.

The switching terminals themselves are located in carpet boxes installed on the street or in the premises of pumping and heating points.

Measurements are carried out using specialized instruments. Usually it is a portable pulse reflectometer domestic production. For stationary installation there are also certain devices, but they are of little information and in most cases are not used.

Mounting

The assembly of all elements of the system takes place after welding of the pipeline. And if most of the work on the construction of a heating main is carried out exclusively by specialists and using technology, then with little knowledge in the field of electrics and the presence of a soldering iron, gas burner and a megohmmeter, you can do the installation of remote control yourself. For correct execution, the following sequence should be followed:

• check the integrity of the conductors in the pipe insulation by ringing;
• remove the foam to a depth of 2-3 cm, regardless of the degree of its wetting;

• carefully unwind and straighten the conductors rolled up for transportation;
• install plastic supports on the pipe, secure them with tape;
• strip conductors sandpaper and degrease;
• tension the conductors within reasonable limits (excessive tension can cause the wire to break due to the thermal expansion of the pipe, insufficient to sag the conductor and contact with the pipe);
• connection and soldering of conductors to each other (do not confuse the signal and transit wires with each other);

• press the wires into special slots in plastic stands;
• evaluate the strength of the connection with your hands;
• degrease with a solvent and dry the ends of the shell pipes with a gas burner for subsequent installation of the coupling;
• heating the prepared ends to a temperature of 60 degrees and installing glue;
• slide the sleeve over the connection, having previously removed the white protective film, shrink with a burner flame;
• drill 2 holes in the coupling to assess the tightness and subsequent foaming;
• assess the tightness: a pressure gauge is installed in one hole, air is supplied through the other, the quality of the connection is assessed by holding the pressure;

• cut off the heat-shrinkable tape;
• heat the place at the junction of the sleeve / pipe-sheath and attach one end of the tape;
• symmetrically lay the tape over the joint and fasten it with an overlap;
• heat the lock plate and close the joint of the tape with it;
• seat the tape with a burner flame;
• repressurize with air as described above;
• mix foaming components A and B and pour through the hole into the cavity under the installed coupling;
• when advancing the foam to the hole, install a drain plug to remove air;
• after the end of foaming, clean the surface of the coupling from foam and install a welded plug;
• after assembling the system in the pipe part, build up the conductors at the exit points;
• install carpet drawers;
• lay extended conductors in galvanized pipes from the outlet on the pipe to the installed carpet box;
• install and connect switching terminals in accordance with the project;

• connect stationary detectors;
• perform a full check with a reflectometer.

The description considers the option using heat-shrinkable sleeves, there is another type of joint insulation - electrofusion sleeves. In this case, the process will be a little more difficult due to the use of electrical heating elements but the essence remains the same.

When performing work on the installation of the UEC system, there are also the most common mistakes. They rarely depend on who did the work - the customer himself or the builder. The most important of them is the loose fitting of the couplings. In the absence of tightness, after the first rain, the system may show wetting. The second mistake is the unselected foam at the joints: even if it looks visually completely dry, it often carries an excess of moisture and affects the correct operation of the system. After the discovery of one or another defect, one should observe the dynamics and decide when to make repairs: immediately or during the summer non-heating period.

Repair methods

Repair of the UEC system is sometimes required already at the construction stage. Let's look at a few common cases.

1. The signal wire is broken at the exit from the insulation.

Remove foam before formation required amount conductor and increase the length by soldering an additional wire (you can use leftovers from other joints). When soldering, be careful not to ignite the pipeline insulation.

1. The wire of the UEC system is in contact with the pipe.

If it is impossible to get to the point of contact without violating the integrity of the shell, the 3rd unused wire should be used to connect to the circuit instead of the defective conductor. If all conductors are unsuitable due to manufacturing defects, the supplier must be informed. Depending on its capabilities and your desire, a pipe will be replaced or repaired with a reduction in cost right on the spot. If, for any reason, contact with the supplier is not possible, self repair carried out as follows:

• determination of the place of contact;
• section of the pipe-shell;
• foam sampling;
• elimination of contact, if necessary, soldering of the conductor;
• restoration of the insulation layer;
• restoration of the integrity of the shell pipe using a repair sleeve or an extruder.

During the operation of heating networks, repairs are associated not so much with the restoration of functionality, but with the drying of the foam. The reasons can be very different: construction errors in sealing couplings, rupture of a heat pipe, inaccurate excavation near pipes, and much more. When exposed to moisture the best option is to remove it normal indicators resistance. This is achieved different ways: from drying with the shell open to replacing the insulating layer. The degree of dryness is controlled by a pulse reflectometer. After reaching the required indicators, the restoration of the integrity of the shell is carried out in the same way as described above.

Conclusion

In conclusion, I would like to express the hope that after reading the article, not only private traders building networks to their production building or office, but also services closely involved in the operation of pipelines. Perhaps then there will be much fewer accidents and financial losses during district heating cities.

Olga Ustimkina, rmnt.ru

The article will tell you how the UEC system works in PI pipes and how to do it correctly. The information is useful for those who want to save money and do the installation themselves, and for those who already have experience in using such a heating system, but the remote control is out of order or of poor quality.

Ignorance of the basic principles of operation, incorrect installation of elements and inability to handle devices often lead to the fact that all good things are considered useless or useless. This happened with the system of operational remote control of heating networks: the idea was excellent, but the implementation, as always, let us down. The indifference of the customer, on the one hand, and the “responsible” work of the builders, on the other hand, have led to the fact that in our country, the SODK works correctly at best in 50% of the constructed pipelines, and it is used in 20% of organizations. Taking Europe as an example, even not far away, let's say Poland, you can see that the incorrect operation of the remote control system is equated to an accident on the pipeline with urgent repair work. In our country, it is much more common to see a street excavated in the middle of winter in search of a place for a heat pipe break than the summer maintenance work of a team of electricians. In order to make things clear, let's look at the SODK in heating networks from the very beginning.

Purpose

Pipelines of heating networks from generation to generation remain steel, and the main reason for their destruction is corrosion. It occurs due to contact with moisture, and the outer wall of the metal pipe is more susceptible to rust. The main function of the SODK is to control the dryness of the pipeline insulation. Moreover, the reason is indicated without distinction as the ingress of moisture from the outside due to a defect in the plastic pipe-shell, and the ingress of coolant on the insulation as a result of a defect in the steel heat pipe.

With the help of a special tool and SODK, you can determine:

• wetting of insulation;
• distance to wet insulation;
• direct contact of the SODK wire and a metal pipe;
• breakage of wires of SODK;
• violation of the insulating layer of the connecting cable.

Principle of operation

The system is based on the property of water to increase the conductivity of electric current. Used as insulation in PI pipes, polyurethane foam in the dry state has a huge resistance, which electricians characterize as infinitely large. When moisture enters the foam, the conductivity instantly improves, and devices connected to the system record a decrease in insulation resistance.

Areas of use

It makes sense to use pipelines equipped with an operational remote control system for any underground laying. Quite often, even knowing that the pipeline has a defect and there are significant losses of the coolant, it is almost impossible to determine the location of the gust visually. It is because of this that in winter you have to either dig up the entire street in search of a leak, or wait until the water itself washes its way out. The second option quite often ends in news bulletins with notes that cars, people or anything else that had the misfortune to be nearby failed in the city of N due to an accident on heating networks and a collapse of the earth's surface.

Does not add information content and the presence of the pipeline in the channel. Due to steam, it is not always possible to determine the point of leakage, and earthworks will still be significant and long. The only exception, perhaps, are large passage tunnels with communications, but they are rarely built and are very expensive.

The option of air laying of pipelines is the place where the UEC system does not make any practical sense. All leaks are visible to the naked eye and waste for additional control is useless.

Structure and structure

PI pipes used in heating networks are composed of steel pipe, polyethylene jacket pipe and polyurethane foam as insulation. In this foam there are 3 copper conductors with a cross section of 1.5 mm 2 with a resistivity from 0.012 to 0.015 Ohm / m. The wires located in the upper part are assembled into a circuit, in the position “without 10 minutes 2 hours”, the third one remains unused. The signal or main conductor is considered to be located to the right in the direction of the coolant. It enters all branches and it is by it that the condition of the pipes is determined. The left conductor is transit, its main function is to create a loop.

Connecting cables are used to extend cable outlets and connect pipelines to switching points. Usually 3 or 5 cores with the same cross section of 1.5 mm.

The switching terminals themselves are located in carpet boxes installed on the street or in the premises of pumping and heating points.

Measurements are carried out using specialized instruments. Usually it is a portable impulse reflectometer of domestic production. For a stationary installation, there are also certain devices, but they are of little information and in most cases are not used.

Mounting

The assembly of all elements of the system takes place after welding of the pipeline. And if most of the work on the construction of the heating main is carried out exclusively by specialists and using technology, then with little knowledge in the field of electrics and the presence of a soldering iron, gas burner and megohmmeter, you can do the installation of remote control yourself. For correct execution, the following sequence should be followed:

• check the integrity of the conductors in the pipe insulation by ringing;
• remove the foam to a depth of 2-3 cm, regardless of the degree of its wetting;

• carefully unwind and straighten the conductors rolled up for transportation;
• install plastic supports on the pipe, secure them with tape;
• clean the conductors with sandpaper and degrease;
• tension the conductors within reasonable limits (excessive tension can cause the wire to break due to the thermal expansion of the pipe, insufficient to sag the conductor and contact with the pipe);
• connection and soldering of conductors to each other (do not confuse the signal and transit wires with each other);

• press the wires into special slots in plastic stands;
• evaluate the strength of the connection with your hands;
• degrease with a solvent and dry the ends of the shell pipes with a gas burner for subsequent installation of the coupling;
• heating the prepared ends to a temperature of 60 degrees and installing glue;
• slide the sleeve over the connection, having previously removed the white protective film, shrink with a burner flame;
• drill 2 holes in the coupling to assess the tightness and subsequent foaming;
• assess the tightness: a pressure gauge is installed in one hole, air is supplied through the other, the quality of the connection is assessed by holding the pressure;

• cut off the heat-shrinkable tape;
• heat the place at the junction of the sleeve / pipe-sheath and attach one end of the tape;
• symmetrically lay the tape over the joint and fasten it with an overlap;
• heat the lock plate and close the joint of the tape with it;
• seat the tape with a burner flame;
• repressurize with air as described above;
• mix foaming components A and B and pour through the hole into the cavity under the installed coupling;
• when advancing the foam to the hole, install a drain plug to remove air;
• after the end of foaming, clean the surface of the coupling from foam and install a welded plug;
• after assembling the system in the pipe part, build up the conductors at the exit points;
• install carpet drawers;
• lay extended conductors in galvanized pipes from the outlet on the pipe to the installed carpet box;
• install and connect switching terminals in accordance with the project;

• connect stationary detectors;
• perform a full check with a reflectometer.

The description considers the option using heat-shrinkable sleeves, there is another type of joint insulation - electrofusion sleeves. In this case, the process will be a little more complicated due to the use of electric heating elements, but the essence will remain the same.

When performing work on the installation of the UEC system, there are also the most common mistakes. They rarely depend on who did the work - the customer himself or the builder. The most important of them is the loose fitting of the couplings. In the absence of tightness, after the first rain, the system may show wetting. The second mistake is the unselected foam at the joints: even if it looks visually completely dry, it often carries an excess of moisture and affects the correct operation of the system. After the discovery of one or another defect, one should observe the dynamics and decide when to make repairs: immediately or during the summer non-heating period.

Repair methods

Repair of the UEC system is sometimes required already at the construction stage. Let's look at a few common cases.

1. The signal wire is broken at the exit from the insulation.

It is necessary to remove the foam until the required amount of conductor is formed and increase the length by soldering an additional wire (you can use the remnants from other joints). When soldering, be careful not to ignite the pipeline insulation.

1. The wire of the UEC system is in contact with the pipe.

If it is impossible to get to the point of contact without violating the integrity of the shell, the 3rd unused wire should be used to connect to the circuit instead of the defective conductor. If all conductors are unsuitable due to manufacturing defects, the supplier must be informed. Depending on its capabilities and your desire, a pipe will be replaced or repaired with a reduction in cost right on the spot. If, for any reason, communication with the supplier is not possible, self-repair is carried out as follows:

• determination of the place of contact;
• section of the pipe-shell;
• foam sampling;
• elimination of contact, if necessary, soldering of the conductor;
• restoration of the insulation layer;
• restoration of the integrity of the shell pipe using a repair sleeve or an extruder.

During the operation of heating networks, repairs are associated not so much with the restoration of functionality, but with the drying of the foam. The reasons can be very different: construction errors in sealing couplings, rupture of a heat pipe, inaccurate excavation near pipes, and much more. If moisture gets in, the best option is to remove it to normal resistance values. This is achieved in various ways: from drying with the shell open to replacing the insulating layer. The degree of dryness is controlled by a pulse reflectometer. After reaching the required indicators, the restoration of the integrity of the shell is carried out in the same way as described above.

Conclusion

Finally, I would like to express the hope that after reading the article, not only private traders building networks to their production building or office, but also services closely involved in the operation of pipelines will think about the need to use a control system. Perhaps then there will be much fewer accidents and financial losses in the case of district heating of cities.

Olga Ustimkina, rmnt.ru