The need to repair and/or renovate the often several decades old, aged and more and more frequently damaged supply pipelines, including concrete and reinforced concrete sewers is a more and more urgent problem worldwide.

The technical experts developed several technologies to solve this problem.

The essence of one of these methods, known as"liner"technology in the field, is to place into the pipelin-sewer-a synthetic resin impregnated insert hose having a matrix structure, it is pressed onto the inside pipe surface to be repaired/renovated, and the two-component resin is polymerized in this state of the insert hose. By hardening of the resin, an inside shell structure will upgrade the existing pipeline, e. g. concrete wastewater sewer for further decades. In the course of the resin polymerization, e. g. in the case of wastewater sewer, the continuous sewerage of the wastewater shall be provided, consequently, the structure, the so-called"packer"which presses the insert hose to the sewer wall shall be designed to allow the wastewater flowing through.

Providing a given sewer section with such a lining presumes the application of a relatively costly equipment, including, among others, a remote control measurement and control vehicle moving in the sewer, a robot equipped with TV camera, and a control unit located above the ground. Both of the economical utilization of the equipment and the need for normal sewer use require the possible shortest period to carry out the"lining", therefore, the experts aim at achieving the minimum technology time consumption of all parts of the operation.

Polymerization of the resin used for the impregnation of the insert hose is a rather time consuming phase during the execution of the"liner"technology, that is why its possible acceleration may result in the considerable reduction of the operation time for the whole technology. There is an indication in the literature that hot water treatment or electric heating has been applied to provide the satisfactory polymerization rate of the insert hose impregnated by synthetic resin. (D. Stein, W. Niederehe: Instandhaltung von Kanalisationen, 2. Auflage, p. 523,"Copeflex-Verfahren", Ernst & Sohn, Berlin 1992.) The hot water treatment is not used for packer repair operations, but the electrical heating, which can be solved by different, e. g. copper, iron, constantan or carbon fiber material wires with electrical resistance chosen according to the actual needs, can effectively accelerate the resin polymerization.

Carbon fibers have been well known for a long time, but were not able to spread widely in the mass production at the different technical fields due to their very high price. As a result of the recent application technique research achievements and of the production rationalizations, the carbon fiber sales grow quickly, and their price shows a decreasing tendency. According to the forecasts, these tendencies will continue in the next some years. This is important for the concerning invention, because carbon fibers have several advantages compared to the metal fibers in the field of"liner"technologies, e. g. full chemical resistance, higher specific strength than of metal fibers, and their surface can be modified,"finished"with different intermediate layers, to provide optimum bond between the carbon fibers and the actually used resin type."Carbon fibers"are meant as any carbon based product which is sold as fiber strand or spin yarn made of cut carbon fibers, consisting of dozens or hundreds of individual fibers, with infinite or nearly infinite length. Net-like products containing carbon fiber strands or carbon fiber yarns in at least their longitudinal direction are also considered as carbon fibers.

The heating structures for the acceleration of polymerization of the synthetic resin impregnated insert hoses, regardless of their material, have to cope with severe technical and application problems. Nowadays, we do not know any electric heating equipment, which would be known as standard one used in the industry. In the following, we aim at explaining these problems, or at least a part of those.

It is obvious that the size of either the metal or the carbon fibers depend on the diameter of the pipelines to be lined, and on the length of the lined section within a wide range. E. g. in the case of gravity wastewater sewers the standard practical pipe diameters in mm are the following: 100,125, 150,175,200,225,250,275,300,350,400,500,600.

A remark: within the"liner"technology it is a tradition to use two phenomena:"short-liner"and"part-liner". The first one means that between two manholes the sewer is lined for a length of 200 to 2200 mm only, i. e. it is a repair of a local damage (the most common"short-liner"size, i. e. insert ring width is about 400 mm). In the case of the"short-liner"technology, packers with stiff core are used up to about 600-mm ring width to press the rings to the sewer wall. Above 600 mm, however, flexible (e. g. corrugated) packers are used, because this is the only way to put those in the sewer through the manholes. In the frames of the"part-liner"technology sections above 2000-2200 mm, but shorter than the full manhole distance are repaired, and/or renovated.

In both of the"short-liner"and"part-liner"technologies the insert ring is made of synthetic resin impregnated glass felt-glass mat combination. An impregnated matrix sheet having a length of about 10-20% more than the nominal perimeter is laid on the packer mantle with overlapping, it is moved into the sewer, and the rubber mantle of the packer is blown up by compressed air, till it is pressed to the pipe section to be lined. During blowing up the mantle, the synthetic resin impregnated glass matrix material slips continuously, till it reaches the inside wall of the lined pipe, and the rubber mantle presses it to the wall with some tenth of bars (max.

1.5 bars).

For the purpose of heating pads, both for the"short-liner"and"part-liner" technologies, rectangle sheets can be used in practice, having a width and length, which are nearly the same as those of the developed mantle made in the pipeline. The heating pads (wires, cords or nets), according to our perception, have to be fixed between two carrier layers, made of materials with net-like structure, low-count textile structure, or low-count non-woven textiles (felt, mat, artificial felt). The applied synthetic resins must be able to impregnate the full heating pad easily, but the carrier layers have to be strong enough to resist the mechanical stresses during the packer blow-up, protecting the heating wires against displacement, damage or rupture. The lower and upper carrier material can be e. g. impregnated or non- impregnated high strength glass net, glass mat, low-count glass textile, synthetic fiber net, synthetic fiber textile, geotextile, etc. The material quality of the lower and upper layers can be the same or different. The mechanical connection between the two layers can and must be provided by gluing, welding, stitching, etc.

Obviously the electric resistance and the power of the heating pad can be varied within wide range-using the same material and cross-section-by applying different voltages. The situation is sophisticated, because the thickness of the matrix material has also to be changed in the function of the diameter (between about 3-12 mm). Therefore, considerably different quantities of resins have to be heated case by case, usually from 15 3°C (this is the average temperature in the sewers) up to at least 50-60°C, to accelerate the polymerization process so much, that the produced heat energy per time unit is nearly equal with or more than the heat energy per time unit, taken by the surrounding. This is the precondition of reaching the quick and nearly optimum quality polymerization of the lining material. Of course, the emitted heat energy depends not only on the amount, but also on the type of resin. The individual resin types used nowadays in the practice, such as polyester, vinylester, epoxy, polyurethane and 3P resins, are considerably different (the detailed description of the 3P synthetic resin can be found in the Hungarian Patent #210 033).

It is also harmful if the temperature of the lining material is too high due to the heat production. In the case of the very often used insert hoses made of non-woven synthetic fiber mixes, the softening temperature of the fibers is an upper limit of the temperature. The expansion temperature of the synthetic resins is between about 100-200°C, depending on the type. In the core region of thicker lining materials, depending on the resin type, the temperature may also reach about 100-200°C. In the case of 3P resins the maximum allowable temperature is 90-95°C, or else the water content of the resin produces foam by steaming.

To provide the shockproof operation, the heating voltage is limited at 48 Volts; therefore, increasing the heating current rate can only increase the heating power. This makes the increase of the input wire cross-sections necessary, but the thick wires are stiff and heavy, and the placing and positioning of the lining materials-lining rings-will be difficult.

The electric resistance of the pads belonging to different pipe diameters and lined lengths can be so large, that in some cases there can be problems with the satisfactory heating along the full perimeter.

Considering that the average skill level of the manpower applied at sewer renovation is lower than the standard construction industry level, it is a high risk to appoint the workers at site to decide on the heating parameters in the case of the"liner"technologies, using rather high number of parameters.

The task of the invention is to provide a procedure and heating equipment for the renovation/repair of existing pipelines, especially concrete or reinforced concrete sewers by means of the"liner"technology described above, especially by"short-liner"or"part-liner", that the acceleration of polymerization of the resin component forming a part of the lining is achieved without any perceptible quality loss of any component (neither the actual resin, nor the impregnated matrix structure).

The invention is also based on the perception that if the carrier material of the heating pads and the heating wires are properly chosen, then they can form a composite with the lining material and the resin, having at least the same strength as the average of the composite, and the heating pad can become an eternal part of the lining, providing a supplemental increase in its strength, thickness and durability, or it can be taken into account during the structural design. Furthermore, our other perception is that the damage of the two-component resin and/or matrix material can be avoided, if the heating power is controlled suitably in the function of electric parameter (s) of the heating wires, and the matrix temperature cannot reach those high values where any component of the matrix might be damaged. It is also our perception that the most effective way of accelerating the resin hardening- in other words, the process will be completed at the highest speed with a maximum safety against any quality loss-if the control of the operation is carried out in the function of the electric resistance change due to the temperature change of the heating wires.

Based on these perceptions, the problem has been solved by the following procedure: a resin impregnated fiber containing material is pressed to the inside surface of the pipeline to be renovated/repaired, and the resin being in that is polymerized, the polymerization is accelerated by heat input produced by a heating equipment containing heating wires connected to an electric source, and the essence of the procedure is that a heating structure, containing at least one heating pad is placed between two, resin impregnable -in actual case, resin impregnated-carrier layers, is placed on the lining material and/or between its layers, the heating power of the heating structure causing the acceleration of the resin polymerization is controlled based on the measurement of temperature values guaranteeing the production of the full resin and/or matrix quality, and the heating structure impregnated by the resin being in the insert hose will be unified with it and will become its part.

It is expedient if the lower and upper carrier material of the heating pads is of net-like structure or low-count textile-structured material, or low-count non-woven textile, e. g. felt, mat or artificial felt, etc. Actually, impregnated or non-impregnated high strength glass net, glass mat, low-count glass textile, geotextile, synthetic fiber net, synthetic fiber textile, etc. can be used.

According to a specific way of carrying the procedure out, the insert hose is continuously heated by the heating structure, the insert hose material temperature is expediently measured by thermo-element, and the heating power is reduced by decreasing the voltage in the heating wires of the heating structure in the function of the measured temperature values.

According to another expedient way of carrying the procedure out, the technology process including the heating is controlled in the function of the resistance changes caused by the temperature changes of the heating wires, being parts of the heating structure. It is advisable to determine the optimum temperature range where the polymerization of the actual resin occurs in the shortest period, but the heat treatment still does not cause any deterioration in the applied materials, furthermore, the operation period of the heating (heat treatment) which lasts from the beginning of the heating till the reaching of the self-supporting state of the resin, is determined; then current is switched to the heating wires, expediently at the standard voltage level, and the heating wires are heated up to a temperature belonging to the upper part of the actual optimum temperature range, expediently to the upper temperature value, and after reaching this temperature, the heating is switched off ; then the resistance of the heating wires is measured at previously fixed time-intervals by switching back the heating current, and the heating wire temperatures are calculated from the measured resistance belonging to said temperatures; at that time when the temperature calculated from the measured resistance decreases to a value being in the lower half of the optimum temperature range, expediently to the lower value, the heating current is let switched on till reaching the temperature value in the upper part of the range; and after elapsing the operation time, the heating current is switched off. The above way of controlling the technological procedure is a control process by nature, allowing that the procedure is controlled as reliably as possible, and can be influenced if necessary.

The solution according to the invention can be perceived also, of course, that a part of the matrix structure is used for heating; the heat transmitted to the system by this way is measured somewhere in the system; and the input power is varied in the function of the temperature history occurring in the whole matrix.

According to another way of carrying out the procedure is that the process is modeled under laboratory conditions, and a control function is created, using calculation of algorithms for the possible technology setups or for a part of those, and the process control is realized adjusted to this control function. By nature, it is a control operation, and, although, it leads to proper results in many cases, the other control solution described earlier provides more reliable and quicker hardening of the resin.

Usually, it is suitable if by heating wires constituted carbon fiber is used in the heating structure. Carbon fibers, as it was mentioned earlier, can be considered as economical solutions even now for both of the"short-liner" and the"part-liner"technologies, and their competitiveness will probably considerably improve in the next years.

One of the heating equipments being object of this invention has a control power unit which can be connected to an electric source; a power input instrument which can be connected to the heating wire system (network) of the heating structure; electric cables containing resistors, and a switch to create connection with the power supply network. The essence of this equipment is that it has a constant value reference resistor, reference resistors, and an operational amplifier serving for the steering of the controllable power unit is connected into the bridge diagonal.

Also another heating equipment is the object of the invention; this equipment has a control power unit that can be connected to an electric power source; a power input instrument that can be connected to the heating wire system (network) of the heating structure, electric cables containing resistors, and a switch to create connection with the power supply network.

This heating equipment can be characterized by a heating resistor connected into an electric cable starting from the control power input unit and connected to a resistance measurement gauge, and by a potentiometer connected to this cable and to the resistance measurement gauge.

We wish to emphasize that the process control based on the resistance changes of the heating wires due to temperature changes has very important advantages. This way, namely, we are able to detect the highest occurring temperature on the heating wire surface, and not the temperature in a matrix point; namely, the temperature of the wire surface is important, because either the resin, or the matrix structure elements may be damaged due to the maximum temperature peaks occurring on the surface of the heating wires.

There is a perfect quality guarantee for the control by heating wire resistance. The heat treatment unit makes a protocol during the control process, which is available for the customer after finishing the job, and it is also a kind of quality document. The continuous heat treatment method based on measurements by thermo-elements gives only limited possibility for that; the subjective handling factors cannot be avoided in that case; it cannot be checked whether the damage has been really occurred, because the resin covers the eventually damaged locations, and the size of the eventual damage cannot be seen.

Related to the heating equipments according to this invention, a favorable factor has to be emphasized: the sign which is necessary for the control is taken at the same place where the heating current is supplied, which allows the very simple setup of the equipment; the control does not need separate instruments or measuring devices.

As mentioned earlier, the thick electric cables which are necessary for the energy supply of the longer linings, are stiff and heavy, and make the placing and positioning of the lining materials difficult. Applying a three- phase heating system can solve this problem. The three coils of the three- phase transformer, each of 48 Volts, are put in star connection, and the star point is grounded. This way all phase points give 48 Volts related to the ground. We connect three cables to the three-phase heating pad so, that the heating resistors are connected between the phase points, and by this way each resistor will havez 48 Volts, i. e. 83 Volts, and the connected current can be decreased accordingly. Another advantage is that, compared to the two cables of the one-phase system, the number of cables has to be increased by 50% only (one more cable), and the capacity grows by a factor of three.

If, eventually, the resistance of the pads is so large, that the heating cannot satisfactorily be provided simultaneously around the full perimeter, the heating pads are formed and applied in another way: the current impulses are applied onto the heating pads just segment by segment, e. g. clockwise, continuously around.

In order to make always high quality, long-lasting linings (minimum requirement: 5 years warranty, the estimated lifetime shall be 50 years), the heat treatment is suitable to make by a pre-programmed heat treatment unit, applying process control.

First, the heat treatment control unit has to measure the resistance of the heating pad, and, for a short time, the temperature dependence of the resistor, which is a clear information on the material quality of the resistance wires constituting the heating pad. This is also a quality control, because if these measurements can be carried out with success, then the heating pad that has been laid onto the packer works, the electric connections are suitable, and the packer provided with lining material can be moved into the sewer.

Of course, also further information is needed for the heat treatment unit to carry out its task properly. At least the type of the resin and the matrix material, the matrix thickness and the material quality of the pipe to be lined have to be given.

After blowing up the packer at site, the heat treatment unit makes one more measurement to check if the heating pad was damaged during moving in or blowing up. If the result of this measurement is the same as the previous one measured on the ground, the heat treatment can be completed by the required way and with the required result. If not, the packer is to be exchanged or held in for such a long time as if the heat treatment did not accelerate the normal polymerization rate.

After beginning the heat treatment, the unit controls the measure of the heat treatment by current impulses, taking into account the previously measured data. This means essentially that in the beginning the unit gives heat impulses for a longer period, and measures the change of resistance, i. e. the average temperature of the heating pad between the two impulses. Later on the heat impulses are decreased, taking into consideration the amount of heat produced and cumulated in the resin. After a certain time the system may reach a state when no further heat impulse is necessary, and the function of the pad is only the measurement of temperature.

Usually, the heat treatment can be considered as completed and the packer rubber mantle can be released, if the heat development in the resin composite is beyond its maximum and begins to decrease. This point of time, however, has to be eventually modified (increased) by a factor defined in advance, because the polymerization process is slower at the edges where only some mm and having decreasing thickness resin layer has been pressed out, than in the core zones of the structure, because at these narrow rings without matrix material the heat conductivity has a considerably greater degree. Nevertheless, the packers can only be released when these resin rings do not bond to the protection foil of the packer any more.

By the proper dimensioning of the heating pad it can be achieved that the resin rings at the edges reach the hard kit-like, or hard self-supporting state nearly the same time as in the core zone, and then the packer pressure can be released and the packer with its protection foil can be removed easily.

For the control tasks it is expedient to use PC (personal computer). For jobs with less demand, the task can be solved with more simple control units or regulator units composed of the proper elements.

The use of PC with printer is expedient because the repair can be documented immediately at site, as the authorities or the clients require it. The contractor can prove the most easily by these protocols that a proper and high quality work had been done. The situation is rather easy, because before, during and after the repair the use of a TV camera truck is inevitable.

Most of these diagnostic trucks possess PC and printer of the right quality.

The object of the present patent application is composed by the PC and intermediate units serving for the control and regulation tasks of the technology processes describe above, and by the rich size assortment of the concerning heating pads. Also the less manysided versions are objects of the invention, where the system does not contain any PC.

In the following, the invention will be described in detail based on the attached drawings, containing, first, the diagram showing the polymerization process of the resin accelerated by heating, second, two possible examples of the heating equipment. In the drawings: Fig 1 is a diagram showing the polymerization process of the resin accelerated by controlled heating, Fig 2 is a sketch of heating equipment used to carry out the process, Fig 3 Shows another heating equipment.

As we mentioned earlier, during the technology process, in order to help the polymerization of the two-component synthetic resin, a current with 48 Volt according to the Hungarian Standard is switched to the heating wire stock of the heating structure. The electric resistance of the heating wire bundle can be measured between the two heating input points (see points X in Fig 2 and 3).

The resistance will change proportionally with the warming of the heating wires. Knowing the resistance vs. temperature diagram, the heating wire temperature belonging to the actual resistance value can be calculated.

The process goes on in a two-dimensional state space, where the time (t) is the independent variable and temperature (T) is the controlled (regulated) variable.

The optimum temperature range is an interval where the polymerization occurs in the shortest time, but the temperature still does not cause any deterioration (falling off in quality) in the applied materials.

The operation period is the time range reckoned from the beginning of heating till the reaching of the self-supporting state of the resin.

The optimum temperature interval and the operation period are experimentally determined values, depending on the resin type, the applied matrix material, the pipe diameter and the lining thickness.

The co-ordination of the technology process can be done either by controlling or by regulation. If we work with controlling, the first step is to set the optimum temperature range and the operation period, and then the heating wires are heated up to the upper temperature value of the given temperature range. By reaching the required temperature value, the heating is switched off by interrupting the heating current.

Since there is no way to measure the temperature if the heating is off, it has to be switched back in some (short) periods, set previously. If the temperature calculated from the measured resistance decreases to the set lower value, the heating current remains until we reach the upper temperature value.

After elapsing the operation time, the heating current is not switched back any more, only the output of the measurement impulses is necessary. The output measurement impulses provide information on the cooling of the resin after polymerization, and give a sign when the process is finished.

It can be seen well in Fig 1 that after the initial heating period, with the polymerization of the resin, the exothermic process of the resin will be more and more intensive, so the heating will be switched off for longer and longer periods. When the process turns back, and the heating has to be switched back for keeping the temperature more and more frequently again, it is a sign that the polymerization is slower and the resin starts to be self- supporting. The process can also be shown by a heating period interval function (curve).

To determine the final switch-off time of the heating, there are measured laboratory data for each resin type and each pipe diameter.

The end of the heating period can be determined from the time range and the time interval curve taken under the actual working conditions: when the time determined under laboratory conditions has elapsed, and the heating is switched on for longer and longer periods, the heating has to be switched off finally.

The self-supporting state can be determined similarly, based on a time period measured in laboratory and on the measured temperature. After reaching the self-supporting state, the technology process is finished; the packer can be released and pulled out.

If we wish to control the technology process by regulation, the process described above concerning the controlling has to be modeled under laboratory conditions, and regulation functions have to be created for all possible technology setups with calculation algorithms. The regulation has then to be carried out adjusted to these regulation functions.

Either computer or electronic control gear can solve both of controlling and regulation.

If the technology is carried out by computer control or regulation, the system has to contain the following units: * Heating wire stock, * Electric regulation unit, 'Analogue-digital coder, Connector (e. g. RS 232), Portable personal computer (PC).

The heating wire bundle is connected to the input cables only. The electric regulation unit is placed on the ground, near the manhole. The analogue- digital coder is located in the measuring truck.

The computer supervises and controls the process by means of a special supervising and regulation software, having the following modules: Database handling module to store the control (regulation) parameters, Checking module to test the serviceability of the equipment, Control module to carry out the control task, Regulation module to steer the process with regulation curve adjustment, * Documentation module for preparing the protocol.

In the case of applying electronic control gear, the task has to be fulfilled by building together automatic units.

In the following, the heating equipment types according to the invention are described in detail.

The heating rate-i. e. the heat energy that can be put into the system per second-is limited by the heat conductivity and the allowable maximum local temperature. The latter, due to the water content of the system, may reach maximum 94-96°C in the case of 3P resin, or else the resin begins to foam, and its mechanical properties are deteriorated. Since the heat conductivity of the system is low, the local temperature is also influenced by the setting time of the resin, and simultaneously, the heat conductivity of the surrounding can also vary in a wide range. It is not easy to determine the value of the heating current, the optimum solution is the stabilization of the heating wire temperature, consequently, it is necessary to measure the heating wire temperature. There is a simple way for that if the resistance of the heating wire varies in the function of the wire temperature; i. e. its thermal coefficient is not zero. This condition is fulfilled for most pure, one- component conductor; thermally invariable resistances can only be produced by special alloys. The thermal coefficient of some materials to be taken into account: steel: +5x103, aluminum: +4.2x10-3, bronze: +5x10-3, nickel: +4.3x10-3, copper: +4.25x10-3, carbon fiber:-1.7x10-2, (1/°C).

The resistance can be calculated due to T temperature change as R=Ro (l+TkAT) And if the temperature change and resistance are known, then: AT = (R-Ro)/ (TkRo) where Ro is the resistance of the heating pad in the sewer, at the temperature measured in the vicinity of the damage location.

We stated that, in the case of placing an impregnated lining in a sewer, e. g. concrete sewer, the highest temperature occurs at the surface of the heating wires during the resin polymerization, and, since the wire has good thermal conductivity, this temperature is the same as the inside temperature of the wire. Therefore, if the wire temperature, i. e. the wire resistance is stabilized according to the allowable ultimate temperature, no overheating can be occurred in the lining.

The heating equipment types shown in Fig 1 and 2, using electronic measuring and control units can be used for the stabilization.

The heating equipment shown in Fig 2 is used in analogue mode of operation. In this equipment the Rf heating resistor is connected into a Wheatstone bridge with a Ret constant reference resistor, with R, and R2 reference resistors and with P potentiometer. The A operation amplifier regulates the T controllable power supply unit depending on the voltage difference in the bridge diagonal. The connection points of the heating pad are mentioned, as X. Ube is the electric network connector.

The heating equipment shown in Fig 2 works the following way: Upon switching on, the resistance of Rf is the lowest one, the voltage difference in the bridge diagonal is the highest one, therefore the"A" amplifier initiates the highest If heating current by means of the"T"power supply unit.

Due to If, the heating wire is warmed up, its resistance increases (if its thermal coefficient is positive), the voltage in the bridge diagonal decreases.

This process-goes until the bridge diagonal voltage difference becomes so low that If does not decrease any more, because the If Rf thermal power created by it just does not cover the emitted heat energy per time unit.

If the amplification factor"A"is high: a very small alteration of Rf value (less than 0.1 percent) is enough for alteration of If from 0 to Ifma, i. e. If decreases when the resin's excess reaction heat produces higher temperature and increases in case of higher heat loss by the thermal conductivity.

The heating equipment shown in Fig 3 is used in impulse mode of operation.

The switch is marked with K, the connection points of the heating pad are marked with X, the heating resistor is Rf, the controllable power supply unit is T, the connected electric cable is e, the potentiometer is P, and the resistance meter is R. Ube is the electric network connector, as before.

The heating equipment shown in Fig 3 works the following way: Upon switching on the"K"switch, Ifma, heating current is switched to the Rf heating resistor for tbe = tma, time period. The resistance value is then minimum, and the heating current will be switched off for tM time period. Then the R resistance meter connects itself to the Rf and measures its resistance. If it is lower than the warm resistance value that has been set by the P potentiometer, the Tmax switch-on time will not be reduced. If Rf approaches the set Rfma, value, then the switch-on time will be decreased till the condition is. If the polymerization heat of the resin would rise the temperature, then Rf > Rfmax should be the case, when tbe should be reduced further, till the Rf= Rfmax equation should be fulfilled again.

This mode of operation requires more sophisticated and quick circuits, but, especially if there are large heating current values, it has advantages like high efficiency and robustness against the variation of feeding resistances.

In the following, the invention will be described in detail through examples.

Example 1.

The inside diameter of the sewer section to be repaired is 200 mm; the sewer is made of concrete. A glass mat-glass felt matrix-having a specific mass of 1.150 g/m2 is impregnated with 3P Sl type resin with a pot life of 30 minutes at room temperature, produced by Polinvent Ltd. The impregnated matrix is folded into three parts in longitudinal direction, and a heating pad containing 0.3 mm thick heating wire is placed between the first and the second layers.

Then the matrix containing the heating pad is placed on the mantle of the inflatable robber balloon so, that the folded matrix material is overlapped, forming two layers being able to slip on each other. Each folded layer consists of three original matrix layers and one heating pad (the exact measure of overlapping depends on the perimeter of the released packer).

The electric cables being connected to the control unit through the electric regulation unit are connected to the heating pad. The control unit carries out its tasks according to a preset list of operations (programs). In this case, condition depending (controlling) programs run in the control unit.

The over-ground checking program is run in the control unit.

In case of proper result, the packer provided with matrix material is moved into the sewer section to be repaired. It is there connected to a TV camera robot unit, and by means of that, it is moved and positioned exactly by remote control.

Blowing the packer up to 1.5 bar pressure, the impregnated matrix is pressed onto the inside mantle of the sewer to be repaired. After it, the second, in situ checking program is run in the control unit. If the expected result is obtained, the heat treatment program for the control of the polymerization is started.

In this example, the values of the parameters in Fig 1 are the following: U, r,, = 48 V I 15 A T = Q5°r <BR> <BR> <BR> <BR> <BR> Tmin90°C<BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> Tpacker,down = 80°C<BR> <BR> <BR> <BR> <BR> <BR> <BR> tmeas=IOseC tmeas, int = 1 minute theating, off = 40 minutes tpacker, down = 45 minutes The meaning of the parameters is as follows: Unom = nominal voltage Inom = nominal current intensity Tmax maximum allowable temperature of the heating wire during heating Tri,, minimum allowable temperature of the heating wire during heating Tpacker, down = temperature when the packer may be released because the material is already self-supporting tme = time of measuring measuring time interval theating, off = time when the polymerization reaches a state that the further heating is inefficient tpacker, down = time when the lining becomes self-supporting and the packer can be released.

Before starting the control program, the parameters are set using a data table.

Upon starting the program, it sends a control sign, switching on the heating, and measures the resistance at each measuring interval till the end of the process, and calculates the temperature values belonging to the measured resistance values. When reaching the preset upper temperature, the program sends a sign to stop heating. On the expiration the preset measuring interval tmeas switches back the heating for the measuring time, measures the resistance of the heating wire and calculates the temperature. This is periodically repeated, till the measured temperature decreases to the preset lower value. Then the heating is switched on again till the upper temperature value is reached.

The switch-in and switch-out periods are automatically recorded.

By reaching the preset heat switch-off time, the program checks if the recorded switch-off periods show a decreasing tendency. If yes, the heating is finally switched off, and in the following it will be switched on only for the measurement periods. If not, an error signal is sent. After the error signal, the process invalidates the further operations, and the procedure has to be controlled manually.

By reaching the preset packer releasing time, it checks the actual temperature. If it is within the allowable range, the equipment sends a signal to the operator that the packer may be released. If the condition is not fulfilled, an error signal is sent.

Example 2.

This example is similar to Example 1 in its conditions and parameters, but instead of controlling, regulation is applied.

In this case the control gear runs the technology program along a function, recording the beginning and finishing time of the individual operations on the time axis. In this case there is no possibility for feedback, so the setup of the applied operations has to be prepared by aiming at the safety, instead of maximum polymerization speed. It means that, due to the lower (about 80°C) maximum temperature, the polymerization is slower, therefore, the total time of technology is about 8-10 minutes longer.

Example 3.

Also this example is similar to Example 1 in its conditions and parameters, but here an independent measuring circuit controlling is applied.

In this case a thermo-element measures the temperature of the matrix at the packer side. The heating is continuous, varying the current intensity provides the running within the temperature range.

The solution in this example is less economical than in Example 1 and the conditions for quality control are also worse.

Example 4.

This example is similar to Example 1 in its conditions and parameters, but no heating pad was used for the polymerization and hardening of the resin impregnated matrix. Due to this, the 3P S 1 type resin hardened the traditional way, 4 hours after blowing the packer up, and it was possible to release the packer then.

The difference between the test results in Examples 1 and 4 is significant.

When the heating pad was skipped, i. e. in Example 4, the time needed for resin hardening and packer releasing was longer by 3 hours and 15 minutes.

Example 5.

This example is similar to Example 1 in its conditions, but instead of 3P Se type resin, another resin, 3P Wl was used, having considerably faster polymerization, and 15 minutes pot life at room temperature.

Therefore, some parameters of the heat treatment had to be changed. The applied parameters, using the symbols of Fig 1, were the following: Tmax = 90°C Tmin = 85°C <BR> <BR> <BR> <BR> 0<BR> Tpacker, down-75 C<BR> <BR> <BR> <BR> <BR> <BR> theating, off-20 minutes tpacker, down = 22 minutes As it can be seen from the above parameters, in the case of 3P W1 resin we were able to reach the self-supporting state in about half the time compared to the other example. In other words, a half, using the considerably faster 3P Wl resin instead of the 3P S 1 could reduce the time consumption of the heat treatment.

Example 6.

This example is also similar to Example 1 in its conditions, but in this case we applied MaxPox 15 type epoxy resin and MaxPox 48 type additive for poLymerization, both produced by the CIBA AG. The mix ratio was 2: 1 by mass, with a pot life of 45 minutes at room temperature.

Therefore, we had to change some parameters of the heat treatment in Example 6, as follows: <BR> <BR> <BR> <BR> TmaX= 100°C<BR> <BR> <BR> <BR> <BR> <BR> <BR> T.. = 95°C<BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> Tpacker,down"-'<BR> <BR> <BR> <BR> <BR> <BR> <BR> theatingoff= 60 minutes tpacker, down =65 minutes As it can be seen from the above parameters, in the case of epoxy resin the time periods for switching the heating off and for the packer release had to be increased by 15 minutes, compared to the 3P S 1 resin. The operation time is still considerably shorter than for in the case of traditional lining. Namely, if no heating pad and no heat treatment is applied, the time between packer blowing up and releasing is 5 hours to reach the suitable resin strength.

Example 7.

This example is similar to Example 1 in its conditions, but the heating pad is not made of copper wire but of chopped and stranded carbon fiber yarn with about 0.3 mm diameter.

The parameters applied in this example are approximately the same as in Example 1. Difference was observed in the nominal current intensity, 20 A had to be applied in the case of carbon fiber containing heating pad.

Otherwise, the carbon fiber containing heating pad produced correct result.

The advantageous effects supplied by the invention are the following: The basic advantage of the invention is that the polymerization of the actual resin used in the insert hose is accelerated very much, improving the economy of the whole process by leaps and bounds.

It can be considered as an unexpected effect that the control unit can be provided with such a learning program that assesses the parameters of the individual lining operations continuously, gives information for other insert hoses (with different size and material quality) having no previous data, and where the designers had no calibration programs. In other words, after the determination of the calibrating parameters for some basic types, the system is able to create itself the assessed system of basic parameters, which are necessary for its wider application.

Consequently, the control and regulation system is able to fit continuously to the changing market needs, environmental and authority requirements, being applied very differently in the different countries of the world. This way the system becomes widely applicable in different countries and under different conditions.

Of course, the invention is not limited to the implementation ways detailed in the examples and shown in the drawings, but it can be implemented several ways within the protection area defined in the claims of the patent.