IMPROVEMENTS RELATING TO LINING OF PIPELINES AND PASSAGEWAYS

Abstract: Either (i) flexible resin impregnated lining tube (36) or (ii) a thermoplastic lining tube is placed in a pipeline or passageway to be lined. An apparatus (44) which emits radially directed microwave energy is passed through the lining tube (36) and as it does the radial energy is caused to rotate circumferentially to ensure thay the energy falls evenly on the lining tube. In case (i) the energy causes curing of the resin, so that a rigid lining pipe is formed on the pipeline or passageway, whilst in case (ii) the energy softens the tube enabling it to be expanded onto the pipeline or passageway surface.

Description: Improvements Relating to Lining of Pipelines and Passageways This invention relates to the lining of pipelines and passageways, and concerns a means and method whereby a lining tube which is placed on the inner surface of a pipeline or passageway is subjected to a radiation treatment which has an effect on the material of the lining tube, for a purpose which will appear clear hereinafter. A large industry has been established in the rehabilitation and repair of pipelines and passageways by the placement on the surface of the pipeline or passageway of a lining material in the form of a tube. A now well known method has become known as "cured in place" or CIP. In CIP lining a tube of resin absorbent material is soaked in a curable synthetic resin, and the tube whilst still flexible in nature is introduced into the pipeline or passageway and is inflated onto the pipeline or passageway surface so as to lie thereon and conform thereto. Whilst the tube is so held, the resin ' is allowed or caused to cure (usually heat is applied to accelerate curing) so that there results a hard lining pipe lying on the pipeline or passageway surface. Basic procedures for carrying out this method are set forth in US patents 4009063 and 4064211, although many subsequent patents have been obtained for improvements in the basic process. In another method of applying a lining tube, a rigid thermoplastic material tube is introduced into the pipeline or passageway, and it is subjected to heat so as to soften the plastics material. An internal pressure forces the soft pipe onto the pipeline or passageway surface, and then the pipe is cooled so that the inflated and reshaped thermoplastic pipe forms a lining which functions in a similar manner to a CIP lining discussed above. The heat may be applied to the thermoplastic material at any convenient position e.g. before the thermoplastic material is introduced into the pipeline or passageway or after it is introduced, or both. The present invention applies to each of these lining methods, but it has particular application to CIP linings which are of a nature such that the resin contained therein will remain "quiescent" until activated by some external means. CIP linings with this resin system are described as having a latent resin system. The advantage of this is that the linings can be manufactured and impregnated at some considerable time before they have to be used. In other words impregnated linings can be stored in stock, and then taken from stock to order. This differs from the normal method of performing CIP processes wherein the resin is applied to the lining tube shortly before it is to be used, and the impregnated lining is taken to the site as soon as possible after impregnation so that premature curing will not take place. Indeed, many CIP processes involve impregnating the lining at the location of the site. In practise, latent resin systems have not been utilized to any substantial extent and this invention seeks to provide a method and means whereby latent curing systems can be utilized efficiently and reliably. The method and means can also be used for the treatment of thermoplastic pipes for the softening of same. There have been proposed a number of latent resin systems, each of which involves providing a specific resin formulation or mixture, or the inclusion of some additional means in the resin which renders it quiescent. Thus, in a first proposal, a resin system which could only be activated for curing by means of light radiation was proposed, but difficulties were encountered in practise in causing effective cure using ultra violet lights. An example of a light curing method for a cured in place lining is described in US patent 4581247. Other methods for providing a latent resin system have involved embodying microcapsules in the resin mix, the microcapsules containing the resin catalyst, the provision in the resin of electromagnetically activatable particles, the inclusion of clay particles in which the catalyst is absorbed, and so on. The examples of these methods are disclosed in the following patent applications International Patent Application PCT/GB94/01453, International Patent Application PCT/GB93/00107. In the present invention, use is made of microwave energy, and in accordance with the method of the invention in a first aspect, microwave energy is transmitted axially along the pipeline or passageway, with the lining in place, and means is provided to cause the axially travelling microwave energy to be projected radially outwardly onto the inner surface of the lining tube, and use is made of that energy to condition the lining tube to enable it to be cured in the case of a CIP lining, and heated in the case of a thermoplastic lining tube. Preferably, the microwave energy is directed along an axially extending wave guide, and conversion means is provided at the end of the wave guide in order to deflect the energy into radial direction. The said means to convert it to radial direction may be rotatable so that the energy can be applied not only radially but progressively circumferentially. Typically, an axial wave guide inside the passageway leads to a radial wave guide, and the radial wave guide or both wave guides are rotatable inside the pipeline or passageway. The combined axial and radial wave guides may define for example a T-shape where the radial portion has two diametrically opposite arms, or the radial portion may be of cruciform shape insofar as it has four arms for energy distribution radially of the pipeline or passageway. In fact as many arms as are required may be provided on the radial distribution wave guide; it may even be defined by a pair of discs, in which case it may not be necessary to rotate the radial portion to achieve energy distribution. The concept of causing radically directed microwave energy to rotate so that it can be applied radially and progressively circumferentially forms a separate aspect of the invention. The rotation may be achieved for example by mounting a microwave energy source for rotation inside the pipeline or passageway whilst the source is mounted to direct its microwave energy in a specific radial direction, or alternatively a microwave energy source (such as a dipole) which directs the microwave energy in all radial directions may be associated with a parabolic type reflector which focusses the energy in a specific direction, and that reflector may be mounted for rotation around the source to cause the circumferential progression of the energy. The means for generating the microwave energy e.g. a magnetron, may be located inside the pipeline or passageway and may travel with the wave guide(s) in order to sequentially treat the lining tube throughout its length, or it may be located at ground level where the pipeline or passageway is located underground, as will be the case in many instances. The axial wave guide may be such as to have a degree of flexibility in order to enable the radial wave guide to form the contour of the underground pipeline or passageway. Where the lining tube is a thermoplastic tube, it will require to have embedded therein particles which are polar in nature i.e. they are sensitive to the microwave energy so that the particles heat up, as the plastics material in itself is unlikely to be affected by microwave energy. Many materials are polar in nature including clays, ferrites, chromium dioxide manganese, zinc and so on. In the case of a CIP lining tube, the resin system used must also be sensitive to the microwave energy and if it is not it will have to include an additive such as any of the additives as discussed above. Thus, the resin system may include activatable particles or clays or other absorbent materials such as ferromagnetic materials and graphite containing catalyst, or a combination of these ingredients. Embodiments of the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings, wherein;- Fig. 1 is a view illustrating the insertion of a CIP lining tube in an underground sewer; Fig. 2 is an enlarged view showing a section of the lining tube to illustrate its construction; Fig. 3 is a view similar to Fig. 1, but showing the insertion of a thermoplastic pipe into an underground pipeline which may typically be a water or gas main; Fig. 4 is a view similar to Fig. 2 showing the construction of the lining tube of Fig. 3; Fig. 5 illustrates the method and apparatus of one embodiment of the invention when in position inside either the lining tube of Fig. 1 or the lining tube of Fig. 4; Fig. 6 is an end view looking in the direction of arrow VI in Fig. 5; Fig. 7 shows a view similar to Fig.6 in which a modified radial wave guide arrangement is illustrated; Fig. 8 is a sectional view similar to Fig. 5 illustrating the method and apparatus of another embodiment of the present invention; Fig. 9 is a sectional view similar to Fig. 5 illustrating the method and apparatus of another embodiment of the present invention; Fig. 10 is a sectional view taken on the line IX-IX of Fig. 9; Fig. 11 is a sectional view similar to Fig. 5 illustrating the method and apparatus of yet another embodiment of the present invention; Fig. 12 is a view showing how a microwave energy source may be used according to another embodiment of the invention; and Fig. 13 is a view similar to Fig. 12 showing how the source as used in Fig. 12 can be used for curing a CIP lining. Referring to the drawings, in Fig. 1 is shown the application of a CIP lining tube to an underground sewer 10. The tube illustrated by reference numeral 12 is being applied between manholes 14 and 16 in conventional manner which involves the use of an elbow pipe 18 in manhole 14. To the bottom end of the elbow pipe 18 is attached a leading end of the lining tube 12 after that leading end has been fed through the pipe 18. Water or other everting fluid is then poured into the pipe 18 which causes the tube 12, which is flexible although impregnated with a curable synthetic resin, to evert as shown at 20 into and along the sewer 10, so as to be applied thereto. When the tube has been fully applied between the manholes 14 and 16, the resin is caused to cure so that the lining 12 becomes a hard pipe lying on the surface of the sewer 10. The ends are trimmed and any lateral connections which have been covered up in the process are re-established in order to complete the lining operation. This practise is now extremely well known and is utilized throughout the world. Other methods of placement of the tube 12 onto the sewer 10 are known, and in fact the method of application of the tube to the sewer surface is irrelevant as far as the present invention is concerned. Fig. 2 is included to illustrate the construction of the lining tube 12. It comprises a resin absorbent layer or layers 22 of felt or the like which is or are thoroughly saturated with the synthetic resin to be cured. To the inside is a membrane or film 24 which forms the means whereby the tube can be inflated, and which in the finished product forms a smooth surface enhancing flow through the cured lining. The application of these linings as is well known is for rehabilitation and/or repair of the sewer 10. In the arrangement of Fig. 3, a thermoplastic tube 26 is winched into and along the underground pipeline 28, which may typically be a gas or water pipe, and the diameter of the pipe 26 will be slightly less than that of the pipe 28 to provide the radial clearance 30 shown in Fig. 4. Fig. 3 is self explanatory in illustrating how the pipe 26 is winched into pipe 28, and Fig. 4 shows that the pipe 26 contains activatable particles 32 which are polar in nature and cause teh tube 26 to heat up when subjected to the radiation as described hereinafter. As the tube 26 heats so it softens and the pipe 26 can then be inflated up to the wall of the pipe 28 so as to eliminate the clearance 30, and when the pipe has been so inflated, it is then cooled so as to re- rigidify in the enlarged diameter and so form an effective lining for the pipe 28. Again the ends must be finished, and laterals must be re-established, but such finishing operations form no part of the present invention. Reference 34 in Fig. 3 is a winch rope whose purpose will be self explanatory. Fig. 5 illustrates one embodiment of the present invention in apparatus and in method. In that figure, 36 represents the lining pipe when in position either as shown in Fig. 1 or in Fig. 3, and there is then pulled through the pipe in the direction of arrow 38 an apparatus comprising a magnetron 40 by which microwaves are generated, an axial wave guide 42 along which the microwave energy is supplied, and a radial wave guide 44 by which the energy is directed radially outwardly and onto the lining tube 36. If the tube is a CIP lining tube, the resin will be heated by the action of the microwave energy, and therefore curing will commence. The speed of the apparatus along the lining tube in the direction of arrow 38 will be related to the speed at which the lining material cures. As shown in Fig. 6, the radial wave guide 44 is made up of a pair of diametrically opposite radial arms 46 and 48 which redirect the energy radially outwardly so that it can emit energy from the ends of the arms 46 and 48 onto the lining tube 36 which arms preferably are closed by means of microwave invisible material such as PERSPEX (trade mark) . In order to keep residual moisture which may be in the lining tube clear of the ends of the wave guide arms 46 and 48, there may be flexible skirts 50 at the ends of said arms which bear upon the inner surface of the tube 36. In order to ensure that the entire lining tube 36 is treated with energy, the emergent energy is caused to rotate as indicated by arrow 52. To this end, the entire apparatus may rotate, or it may be arranged so that the radial wave guide 44 only rotates. In the arrangement of Fig. 7, a modified radial wave guide arrangement is shown and it has four arms 54, 56, 58 and 60. As many arms as are required can be provided, as shown in dotted lines, and in fact instead of radial arms there may simply be a pair of spaced parallel discs forming the radial wave guide. In such latter case it may not be necessary to cause the radial wave guide to rotate. An embodiment operating in this way is shown in Figs. 12 and 13. In use, the apparatus shown in Fig. 5 is simply pulled along the inside of the pipeline or passageway whilst the radial wave guide is caused to rotate. The rate of progression of the apparatus is related to the rate of cure of the tube 36, the objective being to ensure complete and efficient cure of the entire lining tube. If necessary, the resin matrix in the lining tube 36 when it is a CIP lining tube will be filled with particles which are activated by the applied microwave energy. When the system is effective, the rapid and efficient heating up of the resin takes place, and when the resin cure commences, it will be self continuing because resin curing is exothermic and heat will be generated to continue the cure. It may therefore simply be a matter of initiating the cure using the microwave energy in which case the apparatus can move along the pipeline or passageway at a faster rate. As indicated, the main application for this invention will be for CIP lining tubes, but as long as a thermoplastic tube contains particles such as 32 which can be activated by the microwave energy, the apparatus and method can be used for such tubes. The thermoplastic tubes which are suitable to be heated by this method are inflated after softening in order to place the tubes on the pipeline to be lined. Care should be taken to ensure that the thermoplastic tubes are softened to the correct degree, because if they are not fully softened, they will when they recool tend to return to the original size whereas if they are heated to too great an extent, they will become too fluid to handle. The heating should be to the extent that the original memory is lost and a new memory in the enlarged state can be imposed. Any suitable means such as energy deflectors or reflectors may be provided if necessary for causing the microwave energy to deflect outwardly onto the tube 36. Also, the axial wave guide 42 may comprise a flexible bellows construction to enable it to flex having regard to the changes in direction of the passageway in which the apparatus is used. Instead of using a conventional wave guide, it is also possible to use a co axial cable with a radial energy distributor (dipole) at the end thereof such as an antenna located at a suitable nodal point. As described hereinafter with such antenna it is possible to use a parabolic mirror to focus the energy so that it is strictly radial in a particular direction, and then the parabolic mirror can be rotatable in order to apply the energy sequentially and circumferentially. Although the energy generating device 40 is shown as being inside the pipeline or passageway, it could be located at ground level, and this is especially so where the energy distributing means is a co axial cable which extends into and along the pipeline or passageway in an axial direction and leads to a radial distributor. The equipment shown in Fig. 5 suitably will be winched through the pipeline or passageway, and will typically include a transformer and electrical feed cable. To facilitate its movement, the equipment may be mounted on skids, and these skids will also maintain the equipment reasonably centrally in the pipeline or passageway. Any suitable frequency of operation may be selected, but at the present the utilization of 2.45 GHz frequency seems most appropriate. With the progression of the apparatus through the lining tube, the lining will be heated progressively, and the interior of the lining in either case preferably will be held under pressure, typically air pressure up to 1 bar. When the flexible seal skirts are used, the apparatus can indeed be used under water and water can be used for the inflation of the lining. Where the lining tubes embody particles to enable them to respond to the microwave energy, it is preferable that these particles be below a size of 10 micron as the smaller particles respond more efficiently to microwave energy. Curie temperature ferrites can be used as the particles and they have the advantage that they will stop heating up as soon as they reach the Curie temperature. If it is desired to monitor the temperature to which the linings are heated, infra red cameras could be used. The energy applied by the apparatus may be controlled by using pulsed mode operation. Suitable mechanical mounting of rotating parts can be effected by conventional arrangements. As indicated herein, the method of applying the microwave energy can be effected in various forms. In each case it is necessary that the microwave energy should be directed radially onto the lining, but this can be achieved in various ways. Several alternative ways are indicated in Figures 8- 11, and it should be mentioned that in relation to the embodiments of these figures, all of the features hereinbefore referred to in relation to previous figures can be employed where appropriate, and therefore further specific details of these features are not described in relation to the embodiments of Figs. 8-11. Only the essential differences are indicated. In the arrangement of Fig. 8, the radio waveguide 70 is constructed as illustrated in Figs. 5 and , and may be modified as described in relation to Fig. 7, and is rotatable by means of a drive motor 72 which drives through gearing 74 and 76 respectively on the motor shaft and on the waveguide 70. A co axial microwave generating cable 78 does not rotate, but it penetrates centrally of the waveguide 70, and has a dipole 80 inside the waveguide which emits the microwave energy radially as indicated by the arrows 82. The operation of the apparatus in Fig. 8 will be readily described insofar as as the waveguide is pulled through the lining tube 36, the waveguide is rotated to distribute the microwave energy onto the lining tube 36. In the arrangement of Figs. 9 and 10, again a coaxial cable 90 is used, and the dipole 92 is at the centre of the waveguide 94. This waveguide 94 is made up of a pair of discs, and within the waveguide is a parabolic reflector 96 which is adapted to be rotated about the dipole 92 by means of a motor 98. As can be seen from Fig. 10, the parabolic reflector 96 focuses the microwave energy 100 (which would otherwise be distributed radially in all directions) so that a beam of the microwave energy impinges upon the lining tube 36, but that beam is progressively rotated around the circumference of the lining tube as the assembly is moved along the inside of the lining tube for the purposes hereinbefore described. In the arrangement of Fig. 11, a microwave energy source such as a magnetron 102 is arranged inside the waveguide 104 and is arranged to direct its beam of microwave energy radially as indicated by arrows 106. The entire waveguide and magnetron are rotated by a motor 108 to cause the progressive application of the energy 106 to the lining tube 36 in a circumferentially progressive manner. Figs. 12 and 13 show other arrangements according to the invention. In Fig. 12, the microwave apparatus is shown as being pulled through an underground sewer 200 by means of a pulling rope 202, which is connected to an eye 204 on the downstream end of the apparatus. The eye is coupled to the wave guide arrangement which comprises a pair of discs 206, 208 which are parallel and spaced to define the microwave energy transmission space (waveguide). At the centre of this space is the antenna 210 which is driven by a magnetron 212 on the outside of the left hand disc 206. The antenna emits the energy in all radial directions and it may or may not be used with a parabolic reflector as described hereinbefore. The magnetron 212 is contained in an insulated casing 214 along with other electrical equipment such as a transformer 216 and a capacitor 218. The capacitor is coupled by means of an insulated electrical cable 220 which leads to ground level and is wound on a cable drum 224 at said ground level. In this arrangement, the cable 220 is guided by means of a cable guide 226 which is supported by framework 228 on the ground surface and on the wall of the manhole 230 which leads to the underground pipe 220. This arrangement can be adopted where the apparatus is for curing say a length of resin impregnated tube positioned at a particular location on the surface of the pipe 200. The discs 206 and 208 may be mesh discs where air is used for pressurising the interior of the pipe 200 and for inflating the length of impregnated tube against the pipe 200. The discs 206, 208 preferably are metallic, and when they are perforated, the perforations should be designed so as not to be related to the wave length of the energy to ensure that the energy is not lost through the perforations but is concentrated at the outer periphery of the discs and is applied to the lining material. Where the discs are to be used under water, the perforations may be ommitted, but there may need to be connecting channels leading to the outsides of the discs, and bridging the wave guide to allow the water to pass from one side of the wave guide to the other to eliminate the discs acting with a piston effect. The edges of the discs preferably are flexible so as to accommodate variations in pipe shape, step joints and pipe intrusions such as root and lateral pipe intrusions. Where the apparatus is used underwater, the sealing effect at the periphery of the discs may require to be more effective. The appropriate power supply connecting through cable 220 will be provided, and this power supply can be varied by adopting a pulsed power supply arrangement. The intention is that the power should be coupled to the magnetron to give a microwave emission or frequency in the order of 2.45 GHz. Fig. 13 basically shows the arrangement of Fig. 12, but when used in connection with a CIP lining which is being everted into the passageway 200 in a manner similar to that illustrated in Fig. 1. Also, the cable guide 226 is omitted, as the elbow pipe 18 will in conventional manner form the cable guide. The top of the pipe 18 may be sealed by means of a split cover 232, 234, so that the inflating pressure can be maintained (when air is used) but otherwise the arrangement of Fig. 13 is identical to that of Fig. 12, and similar reference numerals have been used. Where necessary, the apparatus can incorporate a device for deflecting any reflected waves and providing a means to absorb such reflected waves in order to avoid the reflected waves being returned to the magnetron, which could damage the magnetron. Such deflecting devices are well known and indeed are invisible to the emitted energy but deflect the reflected energy.

Claims: CLAIMS 1. The method of lining a pipeline or passageway wherein a lining tube positioned in the pipeline or passageway has an apparatus passed therethrough, characterised in that the apparatus provides microwave energy radially directed at the inside of the lining tube, and the lining tube is sensitive to that energy in either of two ways namely (i) it has a curable resin therein which is cured by the application of the energy or (ii) it is thermoplastic and contains a particulate polar material which heats up under the action of the microwave energy to soften the tube so that it can be expanded. 2. The method of claim 1, wherein the microwave energy is in the form of one or more radial streams which are rotated about the axis of the pipeline or passageway as the apparatus is passed through the lining tube. 3. The method of claim 2, wherein the said one or more radial streams is/are rotated by rotation of the waveguide. 4. The method of claim 2 or 3, wherein the energy generating source is part of the apparatus, is arranged to direct a stream of microwave energy radially and is rotated about the axis of the pipeline or passageway. 5. The method according to any of claims 1 to 3 wherein the energy is supplied through a co axial cable to a dipole which is arranged to emit the energy radially of the pipeline or passageway. 6. The method according to claim 5, wherein the energy is focussed by a reflector into a beam, and the reflector is rotatable to cause the beam to rotate peripherally of the lining tube. 7. Apparatus for performing the method of claim 1, comprising a microwave energy source, a waveguide adapted to direct energy from the source radially into the lining tube, and means to cause progression of the radially directed energy peripherally of the lining tube. 8. Apparatus according to claim 7, wherein said waveguide is rotable relative to the microwave energy source to effect said peripheral progression. 9. Apparatus according to claim 8, wherein the microwave energy source is fixed relative to the waveguide. 10. Apparatus according to claim 9 wherein the microwave energy source is mounted for rotation with the waveguide. 11. Apparatus according to claim 9, wherein the energy source includes a dipole at the end of a co axial cable. 12. Apparatus according to claim 11, wherein there is a parabolic reflector arranged to focus the energy from the dipole into a radial beam. 13. Aparatus according to claim 12, wherein the waveguide comprises spaced discs and the reflector is adapted to be rotated around the dipole. 14. Apparatus according to any preceding claim 7 to 12, wherein the waveguide is in the form of one or more arms. 15. Apparatus for performing the method of claim 1, comprising a microwave energy source, a waveguide adapted to direct energy from the source radially into the lining tube, said waveguide comprising a pair of spaced discs adapted to lie with their planes transverse to the axis of the pipeline or passageway. 16. Apparatus according to claim 15, wherein the discs have sealing members at the periphery thereof to seal against the pipeline or passageway surface. 17. Apparatus according to claim 15 or 16, wherein the microwave energy source comprises an antenna at the centre of the waveguide. 18. Apparatus according to claim 17, wherein the energy source comprises magnetron connected to the antenna but located outside the waveguide. 19. Apparatus according to claim 18, wherein the magnetron is contained in an insulated cannister along with other electrical components to provide the required output from the magnetron, and the cannister is adapted to travel along the pipeline or passageway with the waveguide, and power is supplied thereto by an electrical cable.

Inventors: CHANDLER BRIAN BURNETT, CHANDLER, BRIAN, BURNETT
Applicants: CHANDLER BRIAN BURNETT, SOUND PIPE LTD, CHANDLER, BRIAN, BURNETT
Application year: 1995
Main classification: B29C63
IPC codes: B29C35, B29C63, F16L55