NL192960C - Replacement pipe for installation in an existing pipeline. - Google Patents

Description

1 192960

Replacement pipe for installation in an existing pipeline

The invention relates to a replacement pipe for installation in an existing pipeline, the replacement pipe consisting of thermoplastic material which is substantially rigid at ambient temperatures, the replacement pipe being made in a collapsed, non-circular shape with reduced dimensions that are smaller than that of the pipeline and is longitudinally folded and heatable for insertion into the pipeline, and, after positioning inside the pipeline, is expandable into a tubular shape with an outer diameter substantially corresponding to the inner diameter of the pipeline below the supplying heat and internal pressure, and in its tube form is stabilizable by cooling. Such a replacement pipe is known and is described in French Patent Specification 1,394,807. Extrusion produces a polyvinyl chloride tube with a diameter substantially equal to or slightly smaller than the inner diameter of the pipeline to be lined. Then the replacement pipe is again heated and flattened in the form of a tape, which is wound on a spool for transport. The wound-up replacement pipe is heated again to unwind and introduce it into the existing pipeline 15. Then, hot steam is passed under pressure through the replacement pipe so that the pipe, through its memory for the thermally stable shape, resumes its tube shape. While the tube is still hot, a piston is pulled through so that the replacement pipe fits tightly against the existing pipeline. Preferably, the flat replacement pipe is folded in two just before insertion into the pipeline by means of a guide through which the replacement pipe slides. The replacement pipe has a wall thickness of 0.5 to 1 mm.

This known replacement pipe has the drawback that the replacement pipe will tend to expand due to its round tube shape memory during heated insertion into the existing pipeline, which will cause its edges to chafe and become damaged along the inside of the existing pipeline , which is undesirable.

It is an object of the invention to overcome these drawbacks.

This object is achieved according to the invention with a replacement pipe as described in the preamble, the replacement pipe having a memory for the reduced, non-circular shape, so that the replacement pipe, when heated to make it flexible for insertion into the pipeline will tend to remain in the reduced, non-circular shape.

This achieves that a thick-walled replacement pipe can easily be inserted into an existing pipeline, without large excavations being required to introduce the usual rigid or semi-rigid thick-walled replacement pipes into an existing pipeline. Namely, because the replacement pipe has a memory for the reduced, non-circular shape, the replacement pipe can be heated to such a temperature that it is sufficiently flexible to easily enter the existing pipeline without the replacement pipe tending to run out. folding, which can prevent damage to the replacement pipe. Because the replacement pipe is flexible, curves or bends in the existing pipeline can be followed by the replacement pipe, which is not possible with the usual rigid or semi-rigid thick-walled replacement pipes. The method according to the invention has the additional advantage that it is possible in a simple manner, if desired, to remove the replacement pipe 40 again by heating the replacement pipe again sufficiently, so that the replacement pipe returns to the collapsed, non-collapsed shape through its memory for the reduced form. circular shape, so that the collapsed replacement pipe can be easily pulled out of the existing pipeline, for example to replace it with a new replacement pipe.

It is noted that, according to European patent application 0.065.886, use is made of a replacement pipe for the internal lining of an existing pipeline, which replacement pipe is given a reduced form. However, this replacement pipe has a tubular shape memory with a circular cross section.

According to a further embodiment, the replacement pipe is collapsed in its reduced form and folded longitudinally, and the replacement pipe has a cross-section with a first and a second 50 legs joined together at a rounded spherical portion, one leg being longer than the other leg, and each leg ending in a rounded spherical free end. The rounded spherical fold and leg ends prevent the risk of the folded parts of the replacement pipe from tearing when folded. This risk exists when the replacement pipe is folded flat. The spherical leg ends also allow steam or other hot fluid to pass through the folded 55 replacement pipe to heat and expand the replacement pipe.

The invention will be elucidated by way of example with reference to the drawing.

192960 2

Figure 1 is a cross-sectional view of a conventional thermoplastic replacement pipe, such as a PVC replacement pipe, used in accordance with the invention in its expanded round state; Figure 2 is a perspective view of the thermoplastic replacement pipe of Figure 1 and of the device for reducing the replacement pipe from its round state to a collapsed, folded state for coil storage; Figure 3 is a cross-sectional view of the thermoplatic replacement pipe of Figure 2 after it has been folded, taken along the line Ill-Ill of Figure 2; Figure 4 is a schematic view showing a method of installing the folded and coil-stored thermoplatic replacement pipe of Figures 2 and 3 within a main sewer from a manhole, with the folded thermoplatic replacement pipe stored on a roll and again is heated before installation in the underground replacement pipe to be repaired; Figure 5 is a schematic sectional view showing a detail of the device for expanding the folded thermoplastic replacement pipe of Figures 2 and 3 and rounding it after it has been introduced into the existing main pipeline shown in Figure 4; Figure 6 is a schematic sectional view showing an alternative construction for expanding and rounding the folded thermoplastic replacement pipe after its introduction into an existing conduit; Figure 7 is a sectional view through a preferred embodiment of the thermoplastic replacement pipe of Figure 1 when folded for installation in an existing underground pipe; Figure 8 is a schematic side view of an apparatus for manufacturing the thermoplastic replacement pipe of Figure 1 in a folded form as shown in Figure 7; Figure 9 is an enlarged scale vertical view of the calibrator of the device of Figure 8 as used in the manufacture of the thermoplastic replacement pipe in the form shown in Figure 7; Figure 10 is a vertical view of a single calibration plate of the calibrator of Figure 9 as viewed from line X-X of Figure 9; Figure 11 is a schematic side view illustrating a method and device for folding a thermoplastic replacement pipe that is manufactured in a round manner for introduction into an existing underground pipe; Figures 12A-E are schematic sectional views taken along lines XIIA-XIIA through XIIE-XIIE of Figure 11, respectively.

Figure 1 shows a pipe 10 used to renew, repair or replace underground pipeline sections such as sewer pipes. This pipe 10 is formed from a thermoplastic material such as PVC, which is usually rigid and thick-walled to have a hoop strength that can withstand external ground and hydraulic pressures to which the pipe can be exposed underground. This pipe 10 can be made flexible by heating to a temperature of at least 105 ° C (200 ° F), but is rigid at above-ground and underground ambient temperatures. By heating again, the pipe 10 becomes flexible and workable again. The thermoplastic material of the pipe 10 has a memory in which the original round tubular shape of the pipe which is later heated and flattened or folded and then cooled to stabilize in its folded shape returns to the original round tubular shape after reheating. Also, if the 45 pipe is initially manufactured in a collapsed and folded form, as shown in Figure 3 and Figure 8 and later heated and expanded to a round shape under internal pressure, and cooled and stabilized in the round shape, return the material to its original folded shape if it is subsequently heated.

Figure 2 illustrates a device 11 with heater 11a for reshaping the round 50 PVC pipe 10. Figure 3 shows a cross section of the pipe 10 after it has been reformed by flattening and folding using the device of Figure 2.

Although the unit 11 in Figure 2 schematically illustrates a pipe folding member, a practical pipe folding device and method are illustrated in more detail in Figure 11 and Figure 12A-E. The round pipe 10, after passage through the heater 11a, is first flattened by a pair of rollers 60, 61 and 55, then passed along a folding wheel 62, and supported by three sets of folding rollers 63, 64, 65. The pair of folding rollers 63 is arranged in in conjunction with the folding wheel 62 to begin folding pipe 10 into a U-shaped shape. Thereafter, the three folding rollers 64 mounted in a 192960 4 convert another type of device for expanding the reduced pipe. Such a device includes a mandrel 50 with heating members 52 therein capable of heating the new pipe to a flexible state. The doom 50 is connected to a pull cable 54 or other means for pulling it through the original pipe.

In another method of heating, rounding and expanding the new pipe, hot water or steam may be passed along the installed but still folded new pipe until the desired temperature is reached at the downstream end. Then the new pipe is expanded with hot water or steam and under pressure to a round shape and to the desired diameter.

In Figures 8, 9, 10 and 11, it can be seen that the folded thermoplastic pipe of Figure 7 is manufactured using extruder 106, which extrudes to a vacuum box 108. A puller 110, which is a series of opposed pinch rollers 111,112 downstream of the vacuum box draws the extruded and molded material under tension from the vacuum box and carries it to a reheating steam tube 114 to a flexible state so that the resulting folded pipe can be wound in its folded form on a storage spool 116. A mold 118 and a pin 120 connect to the extruder outlet. Between the downstream end of the mold 118 and the inlet to the vacuum box 108 there is a spacing 121 of about 3 to 6 decimeters (12-14 inches).

The vacuum cabinet is divided internally by partitions 122,123 into three parts. All three sections are filled with water to a level 124 within the cabinet. The first or upstream section 20 of the cabinet is connected to a negative pressure source 125. Although the entire negative cabinet is under negative pressure as a result of such a connection, maximum negative pressure is present in the upstream portion of the cabinet. A calibrator 126 is provided in the first portion of the vacuum cabinet. The calibrator forms and holds the extruded plastic material in the desired folded shape as the material is cooled and thereby hardens. The water within the vacuum cabinet has a cooling function, and the vacuum applied to the cabinet interacts with the calibrator to keep the plastic material in its desired folded shape.

Figure 9 and Figure 10 show the calibrator comprising a series of calibration plates 128 spaced apart and joined by joining rods 130 and spaced by spacers 132 between plates on the rods. The rods are threaded at their opposite ends and secured by nuts 134. Optionally, the calibrator also includes a central tube 136 with cooling water openings 137 for faster cooling of the plastic material.

Figure 10 shows that the calibration plates 128 include a precision cut opening 138 with an exact circumferential shape and outer dimension of the folded pipe.

In the manufacture of the pipe of Figure 7, untreated plastic blend such as polyvinyl chloride is fed through an inlet hopper 107 into the extruder 106, where the material is heated to a temperature of, for example, about 205 ° C (360 ° F) and then through the mold 118 is extruded where the very hot plastic material meets the pin 120.

When the plastic material enters the calibrator it is very hot and quite liquid, and therefore the calibrator plates 128 are densely positioned at this point to maintain the desired shape. The negative pressure inside the box holds the plastic against the outer circumference of the opening 138 as the cooling water cools the plastic material. If desired, compressed air can be injected from a source 140 into the pin 120 into passages 86, 88, 89 of the folded plastic molding to ensure that the plastic does not collapse. Once the plastic material reaches the down-45 current end of calibrator 126, it is cooled and retains its shape under tension applied by pull rollers 110.

From the calibration plates, the plastic strip moves increasingly hardening through the second and third chamber of the vacuum cabinet. When the strip 10 leaves the underpressure box it is cool and rigid and has essentially the shape shown in Figure 7.

The folded strip is then passed through a steam tube fed through an inlet 117 and a power supply 115 to reheat the strip into a flexible state so that it can be reeled up on a storage coil 116.

3 192960 "U-shaped arrangement for cooperation with folding wheel 62 to continue the folding process. Finally, a set of four folding rollers 65 is arranged in a U-shaped arrangement for cooperation with the folding wheel 62 to fold the pipe 10 into a U-shaped shape. Then, the folded pipe is passed through a cooled profile mold 66 to stabilize the pipe in the folded form From profile mold 66, the folded pipe can either be stored in predetermined length or passed through a heating pipe and made flexible, for direct insertion into an existing pipe, or be wound flat in a coil in the heating box 18 shown in Figure 4. Thereafter, at the location of the work, the flat pipe mounted on a coil can be reheated in the heating box, and then out the heating box is drawn and folded according to Figure 7 or Figure 12E before being introduced into the pipe to be lined.

It is also possible to feed the thermoplastic pipe unfolded in a flat state in an existing pipe, when the thermoplastic pipe in its round state has a considerably smaller outer diameter than the inner diameter of the pipeline to be repaired. The shape of Figure 7 is preferred for reasons set forth below.

It is preferred that the thermoplastic pipe is initially manufactured in a desired folded shape. Then, when the folded pipe is reheated to make it flexible for insertion into a pipeline to be lined, the pipe will retain its folded shape rather than prematurely return to the round shape until the pipe is fully inserted into the pipeline and up to a round shape can be made.

Preferably, the thermoplastic pipe is wound up onto a storage coil under heating, such as the coil 12 shown in Figure 4. The coil 12 of folded thermoplastic pipe is stored in a housing or heating box 18, which is equipped with a thermostat-controlled heater 24 ; the heating box 18 may be equipped with an air circulation system 19 to ensure that the folded pipe coil will be heated uniformly. The heating box 18 can be mounted on the flat loading bottom of a truck 20 for transport to a work site. The heating box 18 has an access door 21 and may also include a down tube 22 and a roller 23 to facilitate introduction of the folded thermoplastic pipe into an underground pipeline through a vertical access opening such as the manhole 16 of an existing main sewer 14.

In the following, a method for repairing a main sewer will be discussed.

In accordance with one aspect of the invention, the heating box 18 is conveyed to an opening at work, such as the manhole 16, at a repairable underground pipe section such as the main sewer 14. The end of the reduced pipe 10a is connected by clamping members 28 to a pulling line 26. The pipe is made flexible by heating the coil 12 in the heating box by means of heater 24. The pulling line 26 is operated by a winch via the next downstream manhole 16, to pass the flexible folded pipe 10a from coil 12 through tube 22 and to pull tube roll 23 in the existing tube 14 to the next manhole. After insertion of the folded new pipe, it is heated and expanded into a round or substantially round shape to provide a pipe that cures into a thick-walled, rigid shape with sufficient hoop strength to withstand external hydraulic and ground pressures.

Figure 5 shows the expansion of the reduced diameter pipe after it has been drawn into the original pipe to be renewed or replaced. Hereby plugs 30 and 32 are inserted into the opposite ends of the folded flexible pipe. The plug 30 is inserted at the rear end of the new pipe section, which is located at the input end of the existing pipeline. The plug 32 is fitted at the front or drawline end of the new pipe after disconnection from the drawline. Each of the plugs 30 and 32 is provided with circumferentially disposable expandable gasket members 34, which are provided 45 for releasable engagement with the original pipe 14 and the new pipe 10a.

Packing parts 34 are inflated through air pressure lines 36. Plug 30 includes an inlet line 38 for feeding fresh steam or hot water into the new pipe. This line has a control valve 40, a pressure gauge 42 and a relief valve 44. The plug 32 is provided with a drain line 46, which communicates with the area between the two plugs and is provided with a valve 48.

The newly introduced folded pipe, with the plugs inserted at both ends, is then internally heated by passing fresh steam through small passages provided at the folds of the new pipe visible in Figure 7. Shut-off valve 48 is open, so that the entire length of the new pipe is heated. Valve 40 is then closed while pressurized steam via plug 30 pressurizes the folded pipe, causing it to expand into a round shape. If the new pipe has a folded position memory, it must be cooled after reaching its round shape while maintaining internal pressure so that the pipe rises in its round shape. This last step is not necessary if the pipe has a memory for the round shape. Figure 6 shows one

Claims (2)

5 192960 1. Replacement pipe for installation in an existing pipeline, the replacement pipe consisting of thermoplastic material which is substantially rigid at ambient temperature, the replacement pipe 5 being made in a collapsed, non-circular shape with reduced dimensions smaller than that of the pipeline and longitudinally folded and heatable for insertion into the pipeline, and, after positioning inside the pipeline, expandable to a tube shape with an outer diameter of the pipeline while supplying heat and internal pressure, and in its tube shape is stabilizable by cooling, characterized in that the replacement pipe has a memory for the reduced, non-circular shape, so that the replacement pipe, when heated to make it flexible for insertion into the pipeline, will tend to the reduced, non-circular shape. Replacement pipe according to claim 1, characterized in that the replacement pipe is collapsed in its reduced form and folded longitudinally and has a cross section with a first and a second leg joined together at a rounded spherical portion, wherein one leg is longer than the other leg, with each leg ending in a rounded spherical free end. Hereby 2 sheets drawing