Pipe liners and the installation thereof

Abstract

A pipe liner has an elongate duct of thin laminated thermoplastic layers and remains relatively flexible and folded to a flat form. In this form, opposing sides of the duct are pressed into close proximity aided by folding of the duct, so the liner can be stored efficiently. In use, the liner is inserted into a pipe. The liner is subsequently heated and pressed against the inner surface of the pipe to form a close fit. Once the liner cools, it sets in place providing a close fitting pipe lining. In order to ensure adequate and even heating of the pipe liner during installation, heating is provided within the liner. The heating may comprise: a plurality of conductive filaments; electromagnetic susceptor material; or a plurality of magnetic particles.

Claims

1. A pipe liner for use in repair and/or renewal of a pipe, the pipe liner comprising an elongate duct formed from multiple laminated layers of thermoplastic material wherein heating means are provided between successive laminate layers and comprise an electromagnetic susceptor material adapted to heat the pipe liner above the transition temperature of the laminate layers.

2. A pipe liner as claimed in claim 1 wherein the laminate layers are bonded together by the provision of an adhesive there between or are heat bonded.

3. A pipe liner as claimed in claim 1 wherein the laminate layers are helically wound relative to the elongate axis.

4. A pipe liner as claimed in claim 1 wherein the laminate layers are formed from dual-orientated polymer (DOP) strips.

5. A pipe liner as claimed in claim 1 wherein the liner is adapted to comprise a cable duct provided between two laminate layers.

6. A pipe liner as claimed in claim 5 wherein the cable duct is formed from a thermoplastic material having a higher transition temperature than the thermoplastic material forming the laminate layers.

7. A pipe liner as claimed in claim 1 wherein the susceptor material comprises a plurality of susceptor particles provided: within the thermoplastic laminate layers; as a surface coating on the thermoplastic layers; or within an adhesive provided between the thermoplastic layers.

8. A method of installing a pipe liner of the type comprising an elongate duct formed from multiple laminated layers of thermoplastic material wherein heating means are provided between successive laminate layers and comprise an electromagnetic susceptor material adapted to heat the pipe liner above the transition temperature of the laminate layers or a plurality of magnetic particles adapted to have a curie temperature corresponding to the transition temperature of the laminate layers, the method comprising the steps of: inserting the pipe liner into the pipe; heating the pipe liner; and subsequently pressing the pipe liner against the interior surface of the pipe.

9. A method as claimed in claim 8 wherein the liner is adapted to comprise a cable duct and the method includes the step of laying a cable along the cable duct.

10. A method as claimed in claim 8 wherein the method includes the step of inserting successive lengths of pipe liner into the pipe and fusing together lengths of pipe liner.

11. A method as claimed in claim 8 wherein the pressing step is achieved using compressed air or other suitable gas.

12. A method as claimed in claim 8 wherein the pressing step is achieved using a forming tool inserted into the liner and the forming tool is operable to activate the heating means in the pipe liner.

13. A method as claimed in claim 8 wherein the method includes the additional step of monitoring the temperature of the pipe liner during heating.

14. A method as claimed in claim 8 wherein the heating means comprise susceptor material, and the heating is achieved by applying radio-frequency (RF) or microwave (MW) emissions to the pipe liner.

15. A method as claimed in claim 8 wherein the heating means comprise a plurality of magnetic particles adapted to have a curie temperature corresponding to the transition temperature of the laminate layers and the heating is achieved by applying a high frequency magnetic field to the pipe liner.

16. A forming tool for installing a pipe liner of the type comprising an elongate duct formed from multiple laminated layers of thermoplastic material and heating means provided between successive laminate layers comprising electromagnetic susceptor material adapted to heat the pipe liner above the transition temperature of the laminate layers, the tool comprising: emitting means operable to apply radio frequency (RF) or microwave (MW) emissions to the pipe liner.

17. A forming tool as claimed in claim 16 wherein the emitting means is operable to vary the power of the emissions.

18. A forming tool as claimed in claim 16 wherein the tool comprises an infra red detector positioned so as to monitor infra red emission from the liner.

19. A forming tool as claimed in claim 16 wherein the emitting means comprise any of: an RF amplifier and frequency source; a magnetron; an antenna aligned with the axis of the pipe.

20. A forming tool for installing a pipe liner of the type comprising an elongate duct formed from multiple laminated layers of thermoplastic material and heating means provided between successive laminate layers comprising a plurality of magnetic particles adapted to have a curie temperature corresponding to the transition temperature of the laminate, the tool comprising: magnetic means operable to apply a high frequency magnetic field to the pipe liner.

21. A forming tool as claimed in claim 20 wherein the magnetic means comprises any of: a conductive coil; a spiral coil; a pancake coil or multiple coils.

22. A pipe liner for use in repair and/or renewal of a pipe, the pipe liner comprising an elongate duct formed from multiple laminated layers of thermoplastic material wherein heating means are provided between successive laminate layers and comprise a plurality of magnetic particles adapted to have a curie temperature corresponding to the transition temperature of the laminate layers.

23. A pipe liner as claimed in claim 22 wherein the magnetic particles are provided: within the thermoplastic laminate layers; as a surface coating on the thermoplastic layers; or within an adhesive provided between the thermoplastic layers.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) In order that the invention may be more clearly understood an embodiment/embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, of which:

(2) FIG. 1 is a schematic cross-sectional view of a pipe liner according to the present invention;

(3) FIG. 2 is a schematic perspective view of a pipe liner of FIG. 1;

(4) FIG. 3 is a schematic cross-sectional view of the pipe liner of FIGS. 1 and 2 when flattened for storage;

(5) FIG. 4 is a schematic perspective view of the flattened pipe liner of FIG. 3;

(6) FIG. 5 is a schematic illustration of the manufacture of the pipe liner of FIGS. 1-4;

(7) FIG. 6 is a schematic cross-sectional view of an alternative embodiment of a pipe liner according to the present invention wherein the pipe liner incorporates a cable duct;

(8) FIG. 7 is a schematic perspective view of a pipe liner of FIG. 6;

(9) FIG. 8 is a schematic cross-sectional detail illustrating an embodiment of pipe liner according to the present invention provided with one or more conducting filaments;

(10) FIG. 9 is a schematic perspective view of the pipe liner of FIG. 8;

(11) FIG. 10 is a schematic view of the current applied to the filaments of the pipe liner of FIGS. 8 & 9 for heating;

(12) FIG. 11 is a schematic illustration of apparatus according to the present invention for applying the current of FIG. 10;

(13) FIG. 11a is a schematic block diagram of the master current unit shown in FIG. 11;

(14) FIG. 12 is a schematic cross-sectional detail illustrating an embodiment of pipe liner according to the present invention provided with susceptor material or magnetic particles;

(15) FIG. 13 schematically illustrates potential antennas according to the present invention for applying RF/MW emissions to the pipe liner of FIG. 12;

(16) FIG. 14 schematically illustrates a coil arrangement according to the present invention for applying a high frequency magnetic field to the pipe liner of FIG. 12; and

(17) FIG. 15 is a schematic illustration of apparatus according to the present invention for applying the RF/MW emissions of FIG. 13 or the a high frequency magnetic field of FIG. 14.

(18) Turning now to FIGS. 1 & 2, there is shown a pipe liner 1 according to the present invention. The pipe liner 1 comprises an elongate duct 10 formed from multiple laminated layers 11. Each layer 11 is formed of a thermoplastic material. The layers 11 may be bonded together by adhesive (not shown).

(19) The layers 11 are all relatively thin (say 1-2 mm thick). As such, the liner 1 remains relatively flexible and may be folded to a substantially flat form 2 as shown in FIGS. 3 & 4. In this form 2, the opposing sides of the duct 3 are pressed into close proximity aided by folding 4 of the duct 10 at opposing edges. In this manner, the liner 1 can be stored in a more volumetrically efficient fashion than prior art liners. In particular, the flattened liner 2 may be readily wound around a reel or spindle for transport and storage.

(20) Whilst the liner 1 shown in FIGS. 1-4 is comprised of layers 11 in the form of substantially concentric ducts, in a preferred embodiment shown in FIG. 5, the liner 1 may comprise a series of oppositely wound helical spirals 12, 13. In particular, the winding may take the form of a woven braid.

(21) In use, the liner 1 is inserted into a pipe to be lined. Typically, the liner 1 is deployed in flat form 2 from a reel or spindle and pulled/pushed to the end of the pipe or to a suitable break point in the pipe. The liner 1 is subsequently heated and pressed against the inner surface of the pipe to form a close fit. Once the liner 1 cools, it sets in place providing a close fitting pipe lining. The heating and pressing are discussed in greater detail below.

(22) Turning to FIGS. 6 & 7 a further embodiment of the pipe liner 1 is shown. In this embodiment, the liner 1 is provided with a cable duct 13 between two laminate layers 11. The cable duct 13 allows for cables to be rapidly installed, typically by being blown along the duct 13 once the pipe liner 1 is in position. The pipe liner 1 therefore both lines the pipe and provides a secure place for cables out of the flow passage of the pipe.

(23) In order to ensure adequate and even heating of the pipe liner 1 during installation, heating means 20 may be provided within the liner 1. In one embodiment, the heating means 20 may comprise a plurality of conductive filaments 21 as shown in FIG. 8. The filaments 21 are provided between the laminate layers 11 and may be helically wrapped in opposing dimensions as shown in FIG. 9. In this manner, the laminate layers 11 may be heated by resistive losses when a current is applied to the filaments 21. In a preferred embodiment, a pulsed current is applied to the filaments 21 as shown in FIG. 10. In order to control the heating of the liner, the resistance of the filaments is monitored between current pulses 30. As the resistance varies predictably with temperature, the variations in resistance can enable the temperature of the liner 1, during heating, to be controlled by varying the duty cycle of the applied current. This is illustrated schematically in FIG. 10 by the varying width and separation of the pulses 30.

(24) The heating is monitored and controlled by a master unit 31, as shown in FIG. 11 and FIG. 11a. The master unit 31 is provided with connectors 32 for forming electrical connections with the conductive filaments 21 of the pipe liner 1. In this instance, the connectors 32 may further comprise drum sections 33 insertable into the respective ends of the pipe liner 1. The master unit 31 further comprises a power output means 34 for applying an electrical current to the connectors 32; monitoring means 36 for monitoring the characteristics of the applied electrical current and outputting a response thereto; and a control unit 35 for varying the electrical current by the power output means 33 in response to the output of the monitoring means 36. As discussed above, the control unit 35 can be operable to vary the duty cycle of pulsed current. Nevertheless, the control unit 35 may additionally or alternatively vary the magnitude of the current. Furthermore, if the invention is implemented with a steady applied current rather than a pulsed current, the control unit 35 may be operable to vary the magnitude of the steady current.

(25) In order to ensure the pipe liner 1 is adequately pressed against the pipe wall during heating, the drum sections 33 are inserted into respective ends of the pipe liner 1 to form a substantially airtight seal. Air can then be pumped into the sealed pipe liner section via an air inlet valve 37 provided in one of the drum sections 33. After sufficient heating and pressing, the liner can be allowed to cool in place. Subsequently, the air inlet valve 37 can be opened and/or the drum sections 33 removed. Successive lengths of pipe liner 1 may be installed within a long pipe in this fashion. After installation, adjacent lengths of liner 1 may be sealed together by any suitable method, in particular by plastic welding.

(26) As an alternative to the use of electrical filaments described in relation to FIGS. 8-11, the heating means 20 may comprise electromagnetic susceptor material or a plurality of magnetic particles as illustrated schematically in FIG. 12. The susceptor material or magnetic particles may be provided: within the thermoplastic laminate layers; as a surface coating on the thermoplastic layers; or within an adhesive provided between the thermoplastic layers.

(27) Where the heating means comprises susceptor particles, heating is achieved by applying an RF (radio frequency) or MW (microwave) emission to the liner 1. The RF/MW emissions are absorbed by the susceptor material. Accordingly, the susceptor material is heated and heat is transferred by conduction to the liner 1.

(28) The emissions may be applied by an antenna 40 inserted into the liner 1. The antenna 40 can then be passed along the liner 1, successively heating the liner 1 for/during pressing. Some examples of suitable antenna forms are shown in FIG. 13, specifically a quarter wave antenna (FIG. 13a), a helical coil (FIG. 13b) and a horn antenna (FIG. 13c).

(29) Where the heating means comprises magnetic particles, heating is achieved by applying a high frequency magnetic field to the pipe liner 1. The high frequency magnetic field causes heating of the magnetic particles due to hysteresis losses. Accordingly, heat is transferred by conduction to the liner 1. When the magnetic particles are heated above their curie temperature, they no longer exhibit magnetic properties and accordingly cease to be heated by the applied high frequency magnetic field. By selecting the curie temperature of the particles to correspond to the transition temperature of the laminate layers 11, heating of the pipe liner 1 may be controlled.

(30) The high frequency magnetic field may be applied by an antenna 40 inserted into the liner 1. The antenna 40 can then be passed along the liner 1, successively heating the liner 1 for/during pressing. An example of a suitable antenna form is shown in FIG. 14, specifically a spiral coil.

(31) The heating and pressing of the liner 1 in these embodiments may be carried using a similar arrangement to the electrical embodiment of FIG. 11 as is illustrated in FIG. 15. In this figure, a length of pipe liner is once again sealed by drum sections 33 at either end. Air can be pumped into the sealed volume using air inlet valve 37, thereby enabling the liner 1 to be pressed against the inside surface of the pipe.

(32) The antenna 40 is provided within a shielded portion 42 of a pig (pipeline inspection gauge) 41. The pig 41 can be pulled from one end of the liner 1 to the other by means of a tow cable 43 which passes through gland 38 in one of the drum sections 33. A power cable 44 passes through an equivalent gland 38 at the other drum section 33.

(33) In use, the liner section 1 is sealed and air is pumped inside. The antenna 40 is activated and pulled along by means of tow cable 43. The pipe liner 1 is thus heated by the antenna 40 in conjunction with the heating means 20, and pressed against the pipe by the pressure within the sealed liner 1. After sufficient heating and pressing, the liner can be allowed to cool in place. Subsequently, the air inlet valve 37 can be opened and/or the drum sections 33 removed. Successive lengths of pipe liner 1 may be installed within a long pipe in this fashion. After installation, adjacent lengths of liner 1 may be sealed together by any suitable method, in particular by plastic welding.

(34) In some such embodiments, the pig 41 may additionally comprise one or more sprung plates 45 adapted to press outwardly on the liner 1. In such embodiments, it is indeed possible to omit the drums 33 and rely solely on the sprung plates 45 to press the heated liner 1.

(35) In embodiments where the heating means 20 is susceptor material, the pig may also be provided with an infra red sensor (not shown). The infra red sensor may be operable to determine the temperature of the pipe liner 1 and hence the power output of antenna 40 can be varied in response to temperature.

(36) The above embodiments are described by way of example only. Many variations are possible without departing from the scope of the invention as defined in the appended claims.