METHOD AND APPARATUS FOR CURING THE LINING OF A PIPE

Abstract: Curing method and apparatus for curing the lining (4) of a pipe (3) and which comprises a travelling frame (2) for introduction into the pipe (3), a curing device (8) mounted on the frame (2) and operative to cure the inner wall of the lining during travel of the frame along the pipe, and a fluid pressure driven propelling device (11) connected to the frame (2) and operative, upon application of fluid pressure to the pipe, to pull the frame along the pipe.

Description: METHOD AND APPARATUS FOR CURING THE LINING OF A PIPE This invention relates to a method and apparatus for curing the lining of a pipe. In this specification, reference to the lining of a pipe is intended to include many different types of pipe, and particularly underground pipes which may be pre-formed pipes subsequently installed underground, or pipes which are fabricated underground e.g. brick-lmed sewers. Re-lining of existing pipes is a particularly convenient means of repairing existing pipes, conduits, pipelines ano sewer walls . It should be understood therefore that this invention has general application to the lining of pipes. In certain applications, the lining of a pipe wall utilises a knitted glass fabric, optionally with granite or other filler material, plus a curable resin impregnated into the fabric. This type of lining material is particularly suitable for being taken around bends. The lining is then subsequently cured by use of a travelling curing apparatus. A typical known apparatus comprises a frame for introduction into the pipe, a curing lamp mounted on the frame, and a cord attached to the frame. The cord is passed along the pipe and is then used to pull the frame slowly through the pipe, and internally of the lining, thereby curing the lιn_ng as it travels. The curing lamp usually takes the forrr of an ultraviolet lamp, which is capable of curing the resir as the apparatus travels along the pipe. However, heat is necessarily generated by fie ultraviolet light, and in addition the curing action cf the resin also generates heat, and these two factors can cause overheating of the lining, and with risk of combustion of the lining taking place. In order to overcome this problem, pipelines are orten filled with water before the curing apparatus is introduced. The water acts as a coolant, but has the disadvantage of necessitating the use of expensive and potentially dangerous water proof ultra-violet lamps and associated electrical circuits . The invention therefore seeks to provide method and apparatus for curing a lining of a pipe, having improved propelling means. Desirably, the improved propelling means also permits cooling of the internal wall of the lining during the curing process. According to one aspect of the invention there is provided apparatus for curing the lining of a pipe and which comprises : a travelling frame for introduction into the pipe; a curing device mounted, or being capable of being mounted on the frame and operative to cure the inner wall of the lining during travel of the frame dlong the pipe; and a fluid pressure driven propelling device connected to the frame ana operative, upon application of fluid pressure to the pipe, to pull tne frame along the pipe. The apparatus therefore is propelled along the length of the lining by any suitable fluid pressure medium, which acts on the propelling device, and simultaneously the pressure medium also can act as a coolant preventing overheating and possible combustion of the lining. Preferably, compressed air is utilised as the fluiα pressure driving medium, since air is an insulator, and this enables a relatively inexpensive curing device e.g. an ultra ¬ violet lamp, to be utilised for the curing operation, ana there would be no need for an expensive and potentially dangerous electrically insulated lamp, for use m the event of a non insulating tJ jid pressure medium being utilised. In use of known curing αev ces, it is necessary to nave access to both ends of the pipe, enabling the device to be mserted at one end and pulled through the pipe to the other end. By contrast, apparatus according to the invention may be used when only one end of the pipe can be accessed. In this case, the apparatus is propelled from the open end to the closed end, and then pulled back to the open end by a cord attached to the frame. One preferred form of fluid pressure driven propelling device comprises an inflatable parachute or drogue. The diameter of the parachute, when inflated, may be arranged to be larger than the diameter of the pipe along which it is travelling. This is advantageous m that, when the parachute is inflated, the fluid pressure driving medium e.g. air is not free to pass from the high pressure side of the parachute to the low pressure side of the parachute. Therefore, all the pressurised air introduced into the pipe can be used to propel the apparatus along the pipe. If necessary, large pressures can be built-up behind the parachute, if the apparatus is proving particularly difficult to move. However, in other circumstances, it may be desirable for the diameter of the inflated parachute to be less than the diameter of the pipe. This has the advantage that a portion of the fluid pressure medium e.g. compressed air, introduced into the pipe can be used to inflate that parachute and propel the frame, but still leaving a further portion of the medium to travel over the apparatus and the paracnute, and also the curing device as well as the lining, and thereby dissipating any heat generated, and cooling the lining so aβ to minimise the risk of combustion. In a further preferred arrangement, regardless of whether the parachute is oversized or undersized, when inflated, relative to the pipe, the parachute may be arranged to be semi-permeable relative to the fluid pressure driving medium. This has the advantage that a predetermined portion of the medium introduced into the pipe can pass fhrough the parachute, thereby cooling the pipe lining, and with the remamder of the medium being used to inflate the parachute and propel the frame along the pipe. The ratio of the driving and cooling portions of the medium introduced into the pipe can be determined in advance, and will remain constant even if the diameter of the pipe changes. Desirably, the travelling frame is adjustable m width, which enables the frame to be used in pipe linings of different diameter. The diameter of the frame may be adjusted such that the curing device e.g. an ultra-violet lamp, is always m the centre of the pipe and does not lie at the bottom of large pipelines. The frame may have wheels attached thereto to facilitate the motion of the frame along the pipe. The frame may also carry a power source for powering the curing device. The frame may also include a propeller to assist in inflation of the parachute. With such a propeller, there is no need for an external device connected to the end of the pipe for introducing the fluid pressure medium. Such a propeller may be useful in particularly long pipes where the volume of pressurised fluid to be introduced might be excessive, m the absence of the propeller. An alternative embodiment of fluid pressure driven propelling device which may be connected to the frame may comprise a so-called pipeline "pig", of the type used in scraping and cleaning the internal walls of pipelines. Many designs of "pig" have been proposed, and particularly for use in cleaning, the walls of pipelines conveying hydrocarbons, and which include designs of pig which are particularly suitable for negotiating pipeline bends, and which may be particularly suitable for use m the apparatus of the invention. According to a further aspect of the invention, there is provided a method of curing the lining of a pipe utilising an apparatus as defined above, and/or utilising any one or more of the preferred options referred to above. A preferred embodiment of the invention will now be described m detail, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic illustration of a curing apparatus according to the invention, shown in cross section, and ready to travel along the internal wall of a lining of a pipe; and Figures 2a, 2b and 2c show schematically successive stages of use of the curing apparatus of Figure 1 m order to cure the lining of a pipe. Referring to Figure 1, a curing apparatus according to the invention is designated generally by reference 1, and comprises a travelling frame 2 which can be introduced into a pipeline 3 having its internal walls pre-coated with a lining 4. The lining 4 may comprise a knitted fabric, optionally with granite or other fillers, and impregnated with a curable resin. Linings of this type are particularly suitable for application to pipes having surface irregularities, damage, and particularly having pipe bends to be negotiated. The travelling frame 2 includes latera ly projecting arms 5, which have extendable joints 6, which allow the frame 2 to be adjusted m order to fit within the pipeline 3. Also, the adjustment of the frame can allow a frame cross member 7 to be arranged coaxially with respect to pioelme 3. The cross member 7 may serve to mount any suitable type of curing device, and in which the preferred arrangement takes the form of an ultra-violet curing lamp 9. The cross member 7 therefore carries a socket 8 to which the lamp 9 can be connected. The lamp 9 is arranged so that it uniformly illuminates the surrounding wall of the lining 4 so that, during travel of the apparatus along the pipe, it is able simultaneously to cure the resin of the lining. ,The lamp 9 is therefore connected electrically to the socket 8, and which m turn is connected to a supply cable 10. Attached to the end of the frame 2 remote from the power cable 10, there is arranged a fluid pressure driven propelling device which is capable, upon application of fluid pressure to the pipe, to pull the frame along the pipe. In the illustrated embodiment, the propelling device takes the form of a semi-permeable inflatable parachute 11 (shown schematically) which is attached to pulling hook or loop 12 by cables 13. In the illustrated embodiment, the parachute 11 has a slightly larger diameter, when inflated, than that of the pipeline 3. A cord 14 is also attacheα to the frame 2 adjacent to the power cable 10. The cord 14 can be used to pull the frame 2 m an opposite direction along the pipeline 3 if required, as shown m Figure 2c. Both the power cable 10 and the cord 14 pass through a seal 15 which is inserted into the pipeline 3. The seal 15 has an entrance port 16 to which a source of fluid pressure driving medium 17, preferably compressed air, is attached. In use, the ultra-violet lamp 9 is mounted on the frame 2, and the parachute 11 and the frame 2 are then introduced into the pipeline 3 with the parachute 11 remote from the entrance to the pipeline 3, as shown m Figure 2a. The arms 5 of the frame 2 are adjusted until the ultra violet lamp 9 is coaxial with the pipeline 2. The seal 15 is then threaded along the cord 14 and the power cable 10, and introduced into the pipeline 3, thereby sealing the end of the pipeline 3. The entrance port 16 of the seal 15 is connected to a high pressure air source 17 which is used to inflate the parachute 12. However, the frame 2 is held m position by the tension m the cord 14. As soon as the parachute has been corr ctly .r.flated, the ultra violet lamp 9 is activated, and a cnrinα of the pipeline lining 4 commences. The tension in cord 14 is then reduced, and the inflated parachute 11 then slowly pulls the frame 2 along the pipeline 3, and simultaneously curing of the lining 4 takes place, as shown m Figure 2b. As the parachute 11 is semi-permeable, a portion of the high pressure air flows through the parachute 11 and along the pipeline 3. This cools the lining 4, thereby minimising the risk of combustion of the lining. Once the frame 2 reaches the end of the pipeline 3, the source of pressurised air 17 is disconnected and the seal 15 is removed. The cord 14 is then used to pull the frame 2 back along the pipeline 4 to the entrance port 16. The frame is then removed, as shown in Figure 2c. However, while the illustrated embodiment utilises an inflatable parachute 11 as the fluid-pressure medium driven propelling device, it should be understood that other arrangements of propelling device may be utilised m the method and apparatus of the invention. Thus, pipeline cleaning and scraping "pigs" may be used, which, as will be well known to those of ordinary skill in the art, are capable of being propelled along the inner wall of a pipeline by the application of fluid pressure to one side of the pig, and such a pig may therefore be useα m place of the inflatable parachute 11. It is particularly preferred that pigs cf the type capable of easily negotiating bends of pipelines be used in the apparatus of the invention.

Claims: Claims : 1. Apparatus for curing the lining of a pipe and which comprises : a travelling frame for introduction into the pipe; a curing device mounted, or adapted to be mounted on the frame and operative to cure the inner wall of the lining during travel of the frame along the pipe; and a fluid pressure driven propelling device connected to the frame and operative, upon application of fluid pressure to the pipe, to pull the frame along the pipe. 2. Apparatus according to claim 1, in which the propelling device comprises an inflatable parachute or drogue. 3. Apparatus according to claim 2, m which the diameter of the parachute, when inflated, is arranged to be larger than the diameter of the pipe along which it is intended to travel . 4. Apparatus according to claim 2, in which the diameter of the parachute, when inflated, is arranged to be less than the diameter of the pipe along which it is intended to travel . 5. Apparatus according to claim 3 or 4, in which the parachute is arranged to be semi-permeable relative to the fluid pressure driving medium. 6. Apparatus according to any one of the preceding claims, m which the travelling frame ^ s adjustable in width, to enable the frame to be used in pipe linings of different diameter . 7. Apparatus according to any one of the preceding claims, including wheels attached to the frame to facilitate the motion of the frame along the pipe. 8. Apparatus according to any one of tne preceding claims, m which the frame carries a power source for powering the curing device. 9. Apparatus according to claim 2, in which the frame mounts a propeller which is operative to assist in inflation of the parachute. 10. Apparatus according to claim 1, in which the propelling device comprises a pipeline pig. 11. Apparatus according to claim 10, in which the pig is capable of negotiating pipeline bends. 12. Apparatus according to any one of the preceding claims, m which the curing device comprises an ultra violet lamp. 13. A method of curing the lining of a pipe utilising apparatus according to any one of the preceding claims. 14. A method of curing the lining of a pipe using curing apparatus having a travelling frame, a curing device mounted, or capable of being mounted on the frame, and a fluid pressure driven propelling device connected to the frame, in which the method comprises: introducing the apparatus into the pipe; applying power to operate the curing device; and applying fluid pressure to the pipe which is applied to the propelling device in order to pull the frame along the pipe so that curing of the lining takes pla ^ e during travel of the frame along the pipe.

Inventors: RICE NIGEL LEONARD, RICE, NIGEL, LEONARD
Applicants: RICE DOREEN, RICE NIGEL LEONARD, RICE, DOREEN, RICE, NIGEL, LEONARD
Application year: 1998
Main classification: B29C35
IPC codes: B29C35, B29C63, F16L55