MXPA99000470A - Linking for a t - Google Patents

Abstract

The present invention relates to a method for lining an external pipe with a plastic casing, which comprises providing a precursor liner pipe, the precursor liner pipe being produced by a process comprising forming an initial pipe of plastic material which has a first external diameter and deform the initial pipe to reduce its first external diameter to a second external diameter that is smaller than the first external diameter, wherein the precursor liner pipe has the second external diameter and the plastic material that forms the precursor liner pipe is a plastic material with memory that has a memory of the first external diameter, so that if the plastic material with memory is subsequently melted by the application of heat to it and the molten plastic material is adequately supported, the pipe of precursor liner will expand according to its mem Oria to increase the outer diameter of the casing automatically to a value substantially equal to the first outer diameter, insert said precursor liner pipe into the external pipe, provide a heater inside the precursor liner pipe and apply sufficient heat to the pipeline. plastic material for melting the plastic material with memory, so that the external diameter of the casing is automatically expanded according to the memory to a value essentially equal to or at least closer to an internal diameter of the external pipe than to the value of the second external diameter and, simultaneously, support the molten plastic material that forms the expanded and expanding casing pipe, by the gas pressure inside the casing pipe, and when the molten plastic material is cooled to a state of self-support, the casing remains in the expand state gone in relation to the second outer diameter, characterized in that the heater is a fluid fuel burner medium, and the gas pressure inside the casing to support the molten plastic material forming the expanded and expanding coating tube, it is created at least in part by the gaseous products of combustion emitted from the middle of meche

Description

LINKING FOR A PIPE FIELD OF THE INVENTION This invention relates to a method for lining an external pipe with a plastic casing.

BACKGROUND OF THE INVENTION It is known how to line steel and cast iron pipes, for example master gas distribution pipes, by pushing the polyethylene pipe for coating through the external pipe. The casing can have a reduced diameter by pushing the casing through a die immediately before it enters the external pipe. Then, the casing returns elastically back to its original size to tightly line the outer pipe. The reduced diameter of the casing may not be much smaller than the internal diameter of the external piping and thus internal obstructions in the external piping, for example, gaskets and service piping sockets, must be removed to allow the piping of coating to slide through the external pipe.

P1063./99MX SUMMARY OF THE INVENTION It is an object of the invention to provide a method for lining an outer pipe with plastic material that can fit relatively tightly against an inner face of the outer pipe. The method does not necessarily require removing the internal projections or obstructions within the outer pipe before being lined and allows the outer pipe to be lined in the relatively sharp bending portions thereof. According to the invention, a method for lining an external pipe with a plastic material casing comprises providing a precursor liner pipe; The precursor liner pipe is produced by a process comprising forming an initial pipe of plastic material with a first outer diameter and deforming the initial pipeline to reduce its first outer diameter to a second diameter that is smaller than the first outer diameter, where the precursor liner pipe has the second external diameter and the plastic material forming the precursor liner pipe is plastic material with memory, which has memory of the first outer diameter, so that if the plastic material with memory subsequently melts with the application of heat to it and the molten plastic material is P1063 / 99MX appropriately supported the precursor liner pipe will expand according to its memory, to increase the external diameter of the casing pipe automatically to a value essentially equal to the first outer diameter; insert a precursor liner pipe into the outer pipe, provide a fluid fuel lighter medium within the precursor liner pipe and apply sufficient heat to the plastic material, derived from burning the fuel, use the lighter medium to melt the material plastic with memory so that the external diameter of the casing is automatically expanded according to the memory to a value essentially equal to or at least close to an internal diameter of the external piping with respect to the value of the second external diameter and, in Simultaneously, supporting the molten plastic material that forms the expanded casing pipe by the gas pressure inside the casing, the gas pressure is created, at least in part, by the gaseous products of combustion emitted from the medium of the lighter, and when the molten plastic material is cooled to a state of self-support, the casing It remains in the expanded state in relation to the second external diameter. The plastic material can be a polyethylene P1063 / 99MX crosslinked. The first external diameter of the initial pipe can be essentially equal to the internal diameter of the external pipe. In order that the precursor liner pipe can easily pass through the external pipe and avoid the need to remove the projections or internal obstructions of the external pipe and to fit around the folds, the external diameter of the pipe The precursor liner may have a diameter appropriately smaller than the internal diameter of the external pipe. Now, the invention will be described by way of example, with reference to the accompanying drawings in which: BRIEF DESCRIPTION OF THE DRAWINGS OR FIGURES Fig. 1 is a diagrammatic representation, in partial section, of an apparatus used to carry out the invention, shown with a precursor liner pipe in place within an external pipe and a medium of lighter ready to be extracted through the precursor liner pipe; Fig. 2 shows the apparatus of Fig. 1 during the course of the movement of the lighter medium supplying the heat to expand the precursor liner pipe to P1063 / 99MX form a casing that lines the external pipe; Fig. 3 is a diagrammatic view, in partial section, of a fragment of an external pipe that is lined by the method according to the invention; and Fig. 4 is a diagrammatic view, in partial section, of an arrangement at one end of the casing pipe, at which end the lighter medium travels during the course of heating the precursor liner pipe, to cause its expansion and form the casing pipe.

DETAILED DESCRIPTION OF THE INVENTION In the drawings, the references identify similar or equal parts. With reference to the drawings, the external pipe 2 to be lined should be made of ferrous material, for example iron or molten steel, and can be used to charge gases or liquids, for example a gas or water master pipe. Reference 4 indicates, generally, a pipe of plastic material either in the form of a precursor liner pipe 4a or in the form of an expanded precursor to form a casing pipe 4b, to permanently line the external pipe 2. P1063 / 99MX The precursor liner pipe 4a is first manufactured by forming an initial pipe of plastic material, this initial pipe having a solid wall and a first diameter or external diameter essentially equal to the internal diameter of the external pipe 2. The initial pipe is mechanically deformed to reduce its external diameter to a second external diameter that is smaller than the initial external diameter. This is done by pulling the initial pipe through a calibrated die and has the effect of also thickening the wall of the pipe. In this way, the resulting precursor liner pipe 4a has a smaller external diameter than that of the initial pipe, but with a thicker wall. The plastic material forming the precursor liner pipe 4a is a plastic material with memory, since it has a memory of the initial external diameter. When the plastic material forming the precursor liner pipe 4a melts with the application of heat, the precursor liner pipe 4a automatically expands (as long as the molten wall of the pipe is adequately supported internally to prevent landslides or collapse of the pipe. the wall) to reach the external diameter essentially equal to the initial external diameter. The size of the outer diameter of the expanded pipe is retained substantially, subject to some size reduction caused by shrinkage P1063 / 99 X due to cooling, when the expanded pipe is cooled so that the temperature of the wall of the pipe falls below the melting temperature and the wall solidifies and becomes self-supporting. A suitable plastic material for forming the precursor liner pipe 4a is a crosslinked polyethylene which can have a melting temperature of essentially 137 ° C. The cross-linked polyethylene precursor liner pipes 4a can be obtained from Uponor N.V. from Holland. With reference to Figs. 1 and 2, the underground pipe is shown buried in the ground 6, a section of the pipe to be coated is the external pipe 2, has access pits or arrows 8 and 10 excavated in the ground, at opposite ends 12, 14 of the external pipe, those ends are separated (by removal of the pipe portions) from the portions that remain buried 2a and 2b. With reference to Fig. 1, a portion of the length of the precursor liner pipe 4a is inserted through the external pipe 2. The outer diameter of the precursor liner pipe 4a can be approximately three quarters of the internal diameter of the external pipe 2, for example if the pipe 2 has an internal diameter of essentially 100 mm, the outer diameter of the precursor liner pipe 4a can be in essence 75mm. A P1063 / 99 X support frame 16 is mounted in pit 10 and has legs 18, 20 in which a support 22 is mounted, which may be a substantially semi-circular channel section. A chamber or tube 24, which may be made of metal, is mounted on the support 22, and has at one end a hollow connector 26 mounted therein in a fluid-tight manner, and one end of the precursor liner pipe 4a is it unites in a removable and hermetic way to the fluid with the connector. At its opposite end, the tube 24 has an access opening that can be opened as indicated in Fig. 1, by manually lifting a closing gate 28 and can be closed in a fluid-tight manner by manually closing the door 28. of closure as indicated in Fig. 2. An outlet pipe or ventilation chimney 30 ascends vertically out of the pit 10 from the tube 24, inside which the chimney opens. The chimney 30 includes a one-way pressure relief valve 32, which can be adjusted in a variable manner so that the pressure at which the valve opens to release the pressure in the tube 24 can be varied selectively. With particular reference to Figs. 1, 2 and 4, one end of the precursor liner pipe 4a emerges from the pit 8 and is fluidly releasable and fluid-tightly connected with the connector 34, mounted on a P1063 / 99MX fluid-tight form at one end of a recovery chamber or tube 36 that can be made of metal. At the other end of the recovery tube 36, a flange 38 is mounted in a fluid-tight manner. The flange 38 carries tie bolts 40 which engage an annular plate 42 with the flange. A cylindrical seal or ferrule 44 of elastomeric material is held between the flange 38 and the plate 40 and has an axial passage having an internal diameter that may decrease as the compression of the ferrule between the flange and the plate increases, using nuts 46 on the flanges. 40 ligature bolts. A pipe 48 for supplying pressurized air within the interior of the recovery pipe 36 is connected by an air line 50 to an air compressor 52 provided as a towable tow vehicle, the air line includes a manual on / off valve 54 and a pressure regulator 56 by which air is supplied to the recovery tube 36, at a selected variable pressure. The recovery tube 36 is seated on the floor in a support frame comprising the parts 57 of the frame. With reference to Fig. 4, a flexible hose 58 is in a slidable fit through the bushing 44, which provides a relatively fluid tight seal against the hose that may have an armored sheath or cover, formed of braided wire. The P10e3 / 99MX hose 58 is attached at one end to a gas burner 60 consisting of a cylindrical housing 62, which may be made of stainless steel and which contains a cigarette lighter unit 64, which may be of the constant flame type, with a main central nozzle 66 from which the main gas flare 68 emerges, surrounded by smaller nozzles 70 from which flares 72 emerge to stabilize and maintain the constant flame which is at all times arranged to remain within the housing 62. housing 62 is surrounded, adjacent to each end, by the metal support rings 74 and 76 each mounted in its position by at least three head set screws to ensure an annular space 80 between each support ring and the housing, and to maintain a minimum transfer of heat from the housing to the support rings, which keeps them relatively cold. As shown in Figs. 1 and 2, away from the lighter 60, the hose beyond the bushing 44 slidably passes through a guide 82 and then is wound in a single layer on a winch cylinder 84 in a support frame 86. The winch cylinder 84 can be driven by a motor. Because the hose 58 is wrapped in the cylinder in a single layer, then to P1063 / 99MX Any particular speed of cylinder rotation, the hose is wound on it at an essentially constant linear velocity corresponding to the particular speed of the cylinder. The hose 58 can have a length of at least 100 m. Away from the lighter 60, the end of the hose 58 is connected to the winch cylinder 84 with a rotating connector which supplies a mixture of fuel gas and combustion air in the desired proportions, towards the hose for supply to the lighter. This rotary connector is supplied with the fuel gas / combustion air mixture via a line 88 from a control unit 90 in the form of a towable towing vehicle. The fuel gas, which can be propane, is supplied to the control unit 90 through the gas pressure regulator 92 from a gas storage cylinder 94, and the combustion air for mixing with the fuel gas is supplied to the control unit from the air compressor 52, by a line 96 that includes an air pressure regulator 98. As shown in Figs. 3 and 4, the hose 58 includes a flame siphon 100 adjacent the lighter 60, to prevent the passage of any flame from the lighter along the hose to the winch cylinder 84 (Figs 1 and 2).

P1063 / 99MX If desired, the lighter 60 (Figs 3 and 4) may include a flame monitor (not shown), for example a thermocouple, which can observe when the flame inadvertently leaves the monitor to send a signal to the control unit 90 (Fig. 1 and 2) that can initiate an emergency shutdown, for example, by stopping the supply of fuel gas to the lighter and / or stopping the rotation of the winch cylinder 84. The supply of the fuel gas can also be automatically stopped by the control unit 90 if it is detected that the winch cylinder 84 is in an immobilized state by the immobilized detector means (not shown). Also, the control unit 90 is arranged to control the rotational speed of the winch cylinder 84 at a desired selected speed, within a limit of the possible speeds. The hose 58 is positioned outside the winch cylinder 58 and the hose and the lighter 60 pass along the precursor liner 4a from the recovery tube 36 until the lighter reaches the tube 24 and then emerges from there through of the access opening discovered by the raised closing door 28 (Fig. 1) so that the lighter rests on the support 22. The supply of gas / combustion air to the hose 58 is ignited and the gas ignites in the lighter 60 P1063 / 99MX Now, the winch cylinder 84 rotates in a small part of the hose 58 to remove the lit cigarette lighter inside the tube 24 and then the access opening closes when the closing door 28 descends (Fig. 2). With particular reference to Figs. 1 and 2, the winch continues to operate to wind more hose 58 to pull on the lighter 60, emitting the gaseous combustion products through the precursor liner pipe 4a. The gas pressure inside the pipe 4 can reach, relatively quickly, a desired high enough pressure (above the atmospheric pressure) as fixed by the release valve 32, for example within the limit of substantially 25 to substantially 35 mbarg. The heat output of the lighter 60 can be, for example, essentially 28 kW. The lighter 60 can be moved at a constant core velocity, for example substantially 75 m per hour. The heat applied to the precursor liner pipe 4a has a temperature higher than the melting temperature of the plastic material forming the precursor liner pipe. As a result, as the lighter 60 progresses along the precursor liner pipe 4b, the wall of the pipe melts and expands radially automatically, according to the memory of the plastic material, and below the support provided by the lighter. the P1063 / 99MX gas pressure inside the pipe 4. This is exemplified in Fig. 3, where it can be seen that as a result of the radial expansion of the precursor lining pipe 4a, the latter has a thinner wall than the precursor liner pipe, and the lining pipe with the molten wall is making contact in practically the entire area of the inner face of the external pipe 2. As the lighter 60 moves further along the pipe 4, the portions of the molten liner pipe 4b, further away from the lighter, cool and solidify, and the liner pipe is completely self-supporting. However, due to this cooling, the lining pipe 4b can shrink a little so that its external diameter is smaller than the internal diameter of the external pipe 2. Eventually, the lighter 60 has been completely moved through the pipe 4 to convert it into a lining pipe 4b for the external pipe 2 and reaches the recovery pipe 36 in which the lighter rests, when the winch cylinder 84 is stopped . If desired, the flame can be extinguished by cutting off the fuel supply, when the lighter has passed outside the external pipe 2 at end 12 (Figs 1 and 2). The temperature of the gas flame 68 (Fig. 3) can be from about 900 ° C to 1000 ° C. This, P1063 / 99MX the combustion products are very hot and there is a risk of over-burning the plastic material internally in the lining pipe 4b, if the elevated gas pressure inside the pipe 4 is completely due to the exit of products from combustion of the lighter. There may also be gas leaks from line 4 at several junctions in the arrangement and in the closing gate 28 and in the socket 44 which tend to reduce the pressure within the pipe 4. To compensate for these leaks and reduce the risk of burn excessive, air can be supplied under supplemental pressure for the recovery tube 36, through the pressure air line 50. This supplemental air can both cool the combustion products and increase the pressure thereof, due to maintaining the gas pressure in the pipe 4 at the desired level. If the plastic material forming the precursor liner pipe 4a is a cross-linked polyethylene, it has a melting temperature of essentially 137 ° C. The heat applied thereto can be within the temperature limit of essentially 140 ° C to 150 ° C due to the cooling effect of the supplied supplemental air, which can have a flow velocity of substantially four cubic meters per hour inside the tube 36 of recovery.

P10e3 / 99MX

Claims (10)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following CLAIMS is claimed as property: 1. A method for lining an external pipe with a casing of plastic material, comprising providing a precursor liner pipe; the precursor liner pipe is produced by a process comprising forming an initial pipe of plastic material with a first outer diameter and deforming the initial pipe to reduce its first outer diameter to a second outer diameter that is smaller than the first outer diameter, wherein the precursor liner pipe has the second outer diameter and the plastic material forming the precursor liner pipe is a plastic material with memory having a memory of the first outer diameter, so that if the plastic material with memory is subsequently melted by the application of heat thereto, the molten plastic material is suitably supported and the precursor liner pipe is expanded according to its memory to increase the outer diameter of the casing automatically to a value substantially equal to that of the first outer diameter; P1063 / 99MX insert a precursor liner pipe inside the outer pipe, provide a fluid fuel lighter medium inside the precursor liner pipe and apply sufficient heat to the plastic material derived from burning the fuel when using the lighter medium to melt the plastic material with memory, so that the external diameter of the casing is automatically expanded according to the memory to a value essentially equal to or at least close to an internal diameter of the external pipe with respect to the value of the second external diameter and , simultaneously, supporting the molten plastic material that forms the expanded and expanding casing pipe, by gas pressure inside the casing pipe, the gas pressure is created at least in part by the gaseous products of the combustion emitted from the lighter medium, and when the molten plastic material is cooled to a state of autospor The casing pipe remains in the expanded state relative to the second external diameter.
2. 2. The method according to claim 1, wherein the plastic material is a crosslinked polyethylene.
3. 3. A method according to Claim 1 or Claim 2 wherein the lighter means moves through the precursor liner pipe.
4. 4. A method according to any of the P1063 / 99MX. Previous claims, in which the fluid fuel is supplied to the lighter medium through a tube means that applies force to the lighter's medium, which causes the latter to move through the precursor liner pipe.
5. 5. A method according to Claim 4, wherein the hose means transports combustion air to the lighter means. A method according to any one of the preceding claims, wherein the gas pressure inside the liner pipe is maintained at an essentially predetermined value.
6. 6. A method according to any of the preceding claims, wherein the pressure of gas within the liner pipe is maintained at a substantially predetermined value.
7. A method according to claim 6, wherein the sealing arrangements at opposite ends of the precursor liner pipe inhibit gas leaks from the inside of the precursor liner pipe which is in communication with the pressure release means. of gas, set to open at a predetermined value to maintain the gas pressure essentially at a predetermined value.
8. 8. A method according to any of the P1063 / 99MX Previous claims, wherein the supplementary air is supplied to the interior of the precursor liner pipe, in addition to the air supplied to support the combustion of the fuel in * the lighter medium, and the gas pressure inside the lining pipe is a combination of the combustion products and the supplemental air pressure.
9. 9. A method according to Claim 8, wherein the supplemental air cools the combustion products. A method according to any one of the preceding claims, wherein the lighter means comprises a nozzle means within a housing, and a burnt fuel flare of the nozzle means is contained essentially completely within the housing, which It has an opening for the emission of combustion products. P1063 / 99MX SUMMARY OF THE INVENTION A method for lining an external pipe (2) that can be made of ferrous metal, with a casing (4b) of crosslinked polyethylene, consists in initially providing a precursor liner pipe (4a). The precursor liner pipe (4a) is formed by forming an initial pipe of cross-linked polyethylene having an external diameter equal to the internal diameter of the external pipe (2), then the initial pipe is removed through a die to form a pipe of precursor liner (4a) having a diameter smaller than the internal diameter of the external pipe (2). The polyethylene forming the precursor pipe (4a) is a memory material having a material having an external diameter equal to that of the initial pipe, and the precursor pipe (4a) expands to the size of that external diameter automatically when the polyethylene melts. The precursor pipe (4a) is inserted into the external pipe (2) and the polyethylene is melted by extracting through the precursor jacket pipe (4a) a lighter (60) that burns fuel gas supplied with combustion air through a hose (58), by which the lighter is towed. The hot combustion products melt the polyethylene, causing the precursor liner pipe (4a) to expand automatically in the direction of the lining pipe (4b) that is P1063 / 99 X supported, until the polyethylene solidifies during cooling, by gas pressure effect of a predetermined, desired value, inside the lining pipe (4b). The gas pressure is derived from the pressure of the gaseous combustion products and this pressure can be increased with pressure supplied by additional air into the precursor liner pipe (4a). P1063 / 99MX