NO303654B1 - Method and apparatus for installing a casing in a pipe - Google Patents

Description

The present invention relates to a method and device for installing an interwoven, mainly TJ-shaped lining in a pipe as is evident from the preamble to the subsequent, independent claims.

Thus, it relates to thermoplastic coatings for placement inside pipelines, either in an opening phase or as a repair, to protect the inner walls against degradation. For degraded or damaged pipelines, the coating restores their fluid transport properties and prevents further internal degradation. Such a coating to protect the interior of a pipeline is described in French Patent No. 81 07346, dated April 13, 1981.

It is a general object of this invention to provide a method and a device for installing a deformed pipe product in a pipe for use as a pipeline coating of the type described in the Laurent patent.

A method for producing such a tubular pipeline coating product involves a first step of extruding a pipe having a tubular cross-section, and a second step of deforming the extruded pipe into a reduced cross-sectional shape for insertion into a pipe as a coating therein. A special feature of this method for the manufacture of such a pipe product and its installation as a pipeline coating is the use of a thermoplastic material and its temperature and pressure control in the successive forming steps during deformation, and during its return to an ambient usable state when installed in the pipe. It is an object of the invention to provide a method and a device for installing the coating in the pipe for subsequent return of the coating in the pipe to its original, mainly stress-free, pre-deformed cross-section. In practice, the coating design before the deformation has an outer diameter equal to or preferably slightly larger than the inner diameter of the pipe to be protected, whereby the coating is either without tension or preferably under a small circumferential compression; either condition being immediately assumed by the plastic coating which is dependent on the surrounding pipe for its structural support.

It is another object of the invention - to deform an originally extruded tubular cross-section without affecting its structural integrity, and in such a way that its original extruded tubular cross-section can be restored. To achieve this, controlled heat is applied to establish a softened state in the thermoplastic material after its extrusion, while simultaneously subjecting it to deformation tools to reduce its cross-sectional design. When the desired reduction is achieved, the heat is removed and the final continuous length product is then wound onto a spool for storage, transport and subsequent installation and reforming to its original tubular configuration.

While a U-shaped reduced tubular design is particularly shown and described, it must be understood that other cross-sectional designs can be used, either H-shaped or X-shaped, or the like. The mainly U-shape of the coating, which also includes a V-shape, is currently considered to be the most practical and preferred design for such a pipe product.

When practicing this invention, the deformation of the initially extruded tube, which preferably has a cylindrical shape, is increased in a gradual manner by means of forming devices. That is that at least one side of the tubular extruded tube is increasingly depressed to a condition such that the shaped extruded tube is brought to a lateral collapse so that it assumes a reduced substantially U-shaped cross-section symmetrical about a bilateral plane of symmetry passing through the axis to the former round design; and thus a deformed tube is provided. As noted above, this deformation is carried out in the presence of controlled heat substantially below the fluid temperature of the thermoplastic material and such that the plastic material is deformed without adversely affecting its structural integrity or chemical nature, whether in its deformed state or in its subsequently re-established initial state.

The product described here is a thermoplastic pipeline coating that is reduced from its original extruded round cross-section, so that it can be easily pulled into a pipe, and which is then restored to its original extruded cross-section. Assume that the tube to be coated is circular in cross-section and the outer diameter of the originally extruded coating tube is the same or preferably slightly larger in diameter than the inner diameter of the tube to be coated so that the outer surface of the coating comes into perfect interface contact with the inner surface of the tube and preferably under some circumferential compression. This interface contact of the coating within and with the tube eliminates any annular space between them and consequently any requirement to fill such annular spaces. A feature of this coating is its thin-walled design made from a thermoplastic such as polyethylene, nylon, "Teflon", ABS or other such plastic material, whereby the small loss of inside diameter of the flow passage is largely compensated for by the exceptional flow coefficient within the coating which is produced from such a thermoplastic material. For new pipeline projects, expensive pipe materials such as stainless alloys can be replaced with ordinary steel pipe and coated with this product coating, thereby achieving significant cost savings together with the improved fluid tolerance properties of the plastic, which can be chosen so that it is as advantageous as possible. Consequently, pipelines that are structurally in satisfactory condition do not need to be replaced, since this coating product can be installed and replaced as circumstances require.

In accordance with the invention, a method and device of the type mentioned at the outset is provided which is characterized by the features that appear in the subsequent independent method claim and the independent device claim.

In practical use of the methods and device, however, it has been determined that there is often an extension in an axial direction along the side of the deformed tube which forms the legs of the substantially U-shaped design. This is in contrast to the substantial lack of extension of the side of the tube which is not substantially deformed, ie the outer wall or base of the substantially U-shaped tube. The difference in elongation between these opposite sides of the tube when the tube is reformed to its substantially tubular configuration results in a lack of uniform wall thickness around the circumference of the tube. For coated pipes of 203 mm in diameter or less, this difference in elongation does not cause particular problems since the pipe coating remains mainly within the manufacturing tolerances and allowable stresses. When coating pipes with a larger diameter than

203 mm, however, the difference in wall thickness and stresses on the regenerated pipe lining may lie outside these permissible tolerances and stresses. This problem is also exacerbated when a series of deforming rolls having large curved surfaces to effect the deformation of the substantially U-shaped pipeline coating is used. This is because the angular velocities of the upper and lower points of the rollers are many times different from each other and their engagement with the pipe material therefore causes this material to flow due to the friction between the rollers and the pipe. This material flow will especially for pipe coatings that are used for pipes with a large diameter, i.e. larger than

203 mm, causing the formation of walls having different stresses and different thicknesses at different points of circumference.

In order to minimize or eliminate this problem, and in accordance with the present invention, the tubular tube is elongated on its side opposite the folded or deformed side in order to obtain substantially the same elongation of the tube along its opposite sides. A method of effecting this additional extension in accordance with the present invention is based on displacing one of the backing rolls in a direction towards the pipe axis, i.e. towards a deforming roll, to introduce an extension in that side of the pipe which can be compared to the extension of the opposite deformed side of the pipe lining. In this way, the resulting wall thickness and stresses about the wall will be substantially the same when the pipe is deformed and when it is returned to its original tubular shape in use. Accordingly, a backing roller is mounted for movement towards and away from the pipe axis to introduce the extension along that side of the pipe.

For pipe coatings used to coat pipes of 203 mm or less in diameter, such a solution brings the wall thickness and stress tolerances closer to acceptable standards. However, for the coating of pipes with a large diameter, the problem of introducing flow into the plastic material during the deformation remains.

Furthermore, there is a device and a method for deforming a pipe coating which is used to coat pipes with a large diameter, i.e. greater than 203 mm, where substantially equal stresses and extensions are introduced into the pipe around its circumference to achieve equality in wall thickness and stresses in the deformed pipe. While this apparatus and method may be used to deform pipe coatings for use with 203mm or smaller diameter pipe, since the present invention's ability to substantially equalize the wall thicknesses and circumferential stresses around the coating which would otherwise cause problems with larger diameter pipe , the apparatus and method can preferably be used for pipes with a larger diameter. More particularly, the pipe coating apparatus may comprise a pair of fixed rollers mounted 90° apart for receiving tubular pipe from the extruder. A pair of position-adjustable rollers are mounted opposite the fixed rollers. The position-adjustable rollers are mounted for rotary movement about axes normal to each other and suitable sensors are arranged to sense the angular position of each of the position-adjustable rollers and to provide a signal in response to the position to a control device, including a computer.

Downstream of the positioning rollers, there is arranged on one side of the pipe a deformation wheel or roller which is motor-driven and mounted on an axis normal to the axis of the pipeline so that the wheel or roller can be moved about this axis towards and away from the pipe by means of a preferably hydraulic power cylinder. The roller has a hollow edge to receive heating fluid. Generally opposite to the deforming roller on the opposite side of the tube, there is movably arranged a backing or storage roller mounted for movement towards and away from the axis of the tube. Downstream of the deformation and storage rollers, a rail is provided which is mounted for movement towards and away from the pipe by means of a power cylinder for insertion between the legs of the deformed pipe. Mainly opposite to the rail on the opposite side of the pipe, a storage roller is mounted for movement towards and away from the pipe. In addition, two pairs of closing rollers are provided which are axially separated from each other and which can engage with the legs of the substantially U-shaped tube to maintain it in its deformed state.

In operation, the pipe is received between the positioning rollers and its diameter is ascertained by the sensors on the adjustable positioning rollers. The sensors provide the computer with a signal indicative of the diameter. The computer sends signals to the drive mechanism for the<p>ppaging rollers to position them to stretch the side of the pipe opposite the deformed side so that the resulting pipe will have substantially equal extent when deformed and consequently equal wall thickness and stresses about its circumference. The signal indicative of the pipe diameter is also fed to the computer to provide an electrical output signal to actuate the power cylinder to rotate the deformation roller against the pipe to a predetermined position depending on the degree of deformation required for the pipeline coating of that particular diameter. The hollow rim of the wheel is heated by passing hot water or oil into it which fluid has a temperature corresponding to the temperature of the remaining circumference of the tube in the region of its deformation so that the legs of the U-shaped tube, when they are formed, will not tend to move away from each other. In the deformation area, the plastic mass material should be kept in a temperature range of 93-115°C, i.e. approximately or higher than the crystallization melting temperature of the material that forms the coating. After the initial heating of the deformation roll, the pipe coating is therefore deformed by the cooperation between the deformation and storage rolls and subsequent rolls arranged downstream, which will be described. During the deformation, the tube is kept at a temperature approximately at or above the crystallization melting temperature. In this way, the tube will retain its deformed shape while at the same time having a memory of its round shape.

Downstream of the deforming roller, the rail is also positioned in accordance with the diameter of the tube to bear against the fold in the bilateral plane of symmetry. A set of angled support rollers engage the side of the double-walled sections or loops forming the legs of the U-shaped cover to hold these legs in a partially closed position about the rail. Downstream of the rail and the first set of bearing rollers, a second set of bearing rollers bear against these side sections to substantially maintain the side sections in contact with each other. The movement of the stocking rolls towards the deforming roll in accordance with the diameter of the pipe to be deformed enables a comparable elongation of the pipe on the side opposite the deformed side thereof to maintain equality in wall thickness and stresses around the circumference of the coating.

In accordance with this invention, it must be understood that the pipe coating is deformed at a temperature which corresponds to or is slightly above the crystallization melting temperature. For example, the crystallization melting temperature of high-density ethylene is about 113°C. Attempting to deform the pipe at a temperature that is too far above the crystallization melting temperature can result in the loss of the shape memory of the material that makes up the coating, i.e. HDPE, so that it does not return to its original cylindrical cross-sectional design or round shape. However, deformation of the tube coating at a temperature below the crystallization melting point results in a tendency for the tube to move away from its deformed substantially U-shape and to return to its round shape. Thus, temperature control is somewhat critical in the deformation and reforming of the pipe coating formed from a single material such as HDPE.

It has also been found that by mixing a composition of plastic materials, e.g. high density polyethylene and linear low density polyethylene, the composition has two discrete and different crystallization melting temperatures. E.g. it has been found that with a 50-50 weight blend of HDPE and LLDPE, the two crystallization melting points are on the order of about 105 and 113°C. If the tube is heated to a temperature in the range of approximately 105 to 113°C, it has been found that the tube will retain its original shape memory, i.e. round when deformed, while at the same time the tube will maintain itself in its deformed shape for temperatures that lies below this area. Upon reheating to an activation temperature within this range, the tube will recall its original round shape, return to this, and essentially lose any tendency to return to its deformed shape. That is that essentially any memory of the deformed shape will be removed. It must therefore be understood that the temperature ranges between the two discrete crystallization temperatures may vary depending on the materials used and their properties, although such a range may preferably lie within about 5 to 15°. Accordingly, precise temperature control is not as critical when using a mixture of plastic materials compared to the temperature control required when using a single material, e.g. clean

HDPE.

The invention will now be described with reference to the drawings, where

Figure 1 is a block diagram illustrating a method of manufacturing an extruded plastic pipe liner to restore its original extruded cross-sectional configuration;

figures 2a, 2b, 2c, 2d and 2e show cross-sections of the extruded pipe coating in its subsequent deformation stage, and show in dash-dotted lines the cylindrical design of the final coating for comparison with the deformation in each figure;

Figure 3 is an enlarged longitudinal cross-section of the deforming apparatus carrying out the method shown herein for deforming extruded thermoplastic pipe;

Figures 4 to 9 are enlarged detailed cross-sections taken substantially as indicated by lines 4-4, 5-5, 6-6, 7-7, 8-8 and 9-9 of Figure 3;

figure 10 schematically shows a side view of a pulling line that is pulled through a pipe section to be coated according to the invention;.

figure 11 is a schematic side view illustrating a further step in a pipe coating process where a larger diameter draw line is drawn through the pipe section to be coated;

figure 12 is a schematic top view illustrating a temporarily deformed pipe coating being pulled through a pipe section according to the invention;

Figure 13 is a cross section of a pipe section and associated

coating;

figure 14 is a cross-section of a temporarily deformed

pipe coating according to the invention;

Figure 15 is a partial perspective view illustrating a temporarily deformed coating inside a pipe section to be coated;

figure 16 is a schematic side view illustrating the continuation of a pipe coating expansion process according to the invention;

figure 17 is a. side elevation of a pack/expansion kit for

application in the pipe;

figure 18 is a partial side view of the device shown in figure

17;

Figure 19 is a schematic side view illustrating a full

expanded pipe coating according to the invention;

figures 20-22 represent a schematic progression illustrating the formation of a radial flange on a pipe coating according to the invention;

Figure 23 is a top section illustrating a deployment tool;

Figure 24 is a side view of a tool element for use

with the unfolding tool shown in Figure 23;

figure 25 is an end view of a pipe coating according to

the invention;

figure 26 is a schematic side view illustrating several aligned pipe sections with individual pipe coatings according to the invention;

figure 27 is a perspective view of a tubular pipe deformation apparatus for producing deformed pipe coating;

Figure 28 is an enlarged top view of a portion of the deforming apparatus of Figure 27;

figures 29 and 30 are cross-sections of the deformation apparatus taken

generally about lines 29-29 and 30-30 on Figure 28;

figure 31 is a schematic illustration of a method

for installing the pipe lining;

figures 32-34 are more detailed schematic illustrations of the method for installing a deformed pipe coating according to the present invention;

figures 35 and 36 are side elevations of respective injection and exhaust manifolds used in connection with the pipe coating process illustrated in figures 31-34;

Figure 37 is a side elevational view of a rounding tool joined with a plug for use in the installation method shown in Figures 31-34;

Figure 38 is an end elevation of the rounding tool illustrated in Figure 37;

figure 39 is a side elevation of an end ejector which can be used in the method illustrated in figures 31-34;

figure 40 is a curve of the temperature and pressure conditions as an ordinate plotted with time on the abscissa axis for the installation of the coating in the pipe.

Reference is now made to the drawings in which there is shown the deformation of a substantially cylindrical or round tube formed of a thermoplastic material extruded in continuous lengths into a generally U-shaped deformed state so that its largest cross-sectional dimension is reduced in value for introduction into its deformed state, into in a pipe to be coated. Next, the deformed pipe lining is reshaped or re-inflated to its round state to engage with the inner walls of the pipe and thereby form a reconstituted pipeline.

Reference is now made to figure 1 in the drawings, where the entire procedure for pipe forming and deformation is illustrated in its general form. As shown, there is an extruder device E followed by a cooling device Cl which delivers the tube shape into a deformation apparatus D which carries out the product deformation process. After the deformation process, the product is then delivered through a cooling device C2 to establish it at ambient temperature for delivery via a drawing device P and onto a storage coil S or the like. The extruder device E is known in the art and receives the raw thermoplastic material and forces it through an extrusion die 17 by e.g. 177 to 227<0>C using heating devices 18 to achieve this temperature. The cooling device Cl is known technology and is preferably a vacuum cooling device which is fed from a vacuum cooling unit 19 and reduces the tube mold temperature to e.g. 127°C. The deformation apparatus D is influenced by the heat control device H which maintains this necessary deformation temperature of e.g. 127°C. The cooling device C2 is a known technique and reduces the tube mold temperature to the ambient temperature, and is fed e.g. from a cooling tower 20 or similar. During the cooling period, the shape of the deformed coating must be maintained until the pipe reaches an ambient temperature. This shape can be maintained by external pressure such as by means of rollers, belts or straps, or maintained by an internal vacuum. The devices Cl and C2 include pump devices for water recirculation and it must be understood that the aforementioned temperatures can vary according to the circumstances. Pulling device P is also known technology and pulls the final shaped deformed tube product from the preceding apparatus, the pulling force being controlled so that it does not stretch or compress the tube shape in the process of deformation, thereby controlling its wall thickness.

Figures 2-9 show in particular the apparatus and the methods for forming the deformed pipe coating. Referring to the deformed tube sheet L as shown in Figures 2a to 2e of the drawings, the initial extruded design is cylindrical and has inner and outer diameter walls 10 and 11. As shown, there is an upper backing section 12 and a lower deformable section 13. The deformation is bilaterally symmetrical as in the previous embodiment and arranged about a vertical plane of symmetry a and about which the tube formation is folded together by means of bending and folding. Accordingly, there are opposite side sections 14 and 15 which are established by a center fold 16 which inverts the lower deformable section 13 upwards into a lateral relationship with the inner diameter 10 of the backing section 12. Therefore, each side section consists of a side wall extending from a top dead center to the tube shape and bends inwards to continue upwards to the center fold 16. It is clear that the two side sections 14 and 15 thereby fold together into double wall designs which are further folded inwards towards the center symmetry plane a as clearly shown in figure 2e, which is the desired product form.

The steps of deforming the tube according to this embodiment are the following: First, a cylindrical tube shape is extruded as shown in dashed lines in Figures 2a to 2e, thereby establishing an equal wall section, and preferably of cylindrical design. The upper semi-circular part, namely the backing section 12, is deposited and the fold 16 is impressed at the bottom dead center of the tube shape in alignment with the central plane of symmetry and continues upwards to the juxtaposed relationship of the inner wall 10 of the tube shape at the top dead center thereof. It must be understood that the deformation process can be carried out at any angle, as described above on a dead center bottom, but also from the side, the top or any other angle. In this deformation process, the opposing side sections 14 and 15 are turned and/or bent inwards at their lower extremities 21 and 22 so that the walls continue upwards within their respective inner walls 10 and to the fold 16 (see figures 2a to 2d).

The fold 16 is formed by bending the tube shape inwards at the bottom dead center of this to collapse or collapse along the center plane of symmetry. Simultaneously with this collapse, the lower extremities 21 and 22 of the side sections 14 and 15 are also bent inwards as described above. In practice, with this embodiment, it is preferred that none of the pipe shapes are made in several steps in order to be able to gradually adopt the changing design of the pipe shape and without extending its cross-sectional design. However, it must be understood that no coincidence described so far can be carried out in a single step, e.g. by a pipe of small diameter. As shown, however, there are four steps with the coincidence along the center symmetry line a, and for each step there is a backing or bearing against the top section 12, and it is the bottom section 13 that is deformed.

The first collapse step shown in Figure 2a starts the fold 16 by bending and continues to bend the lower extremities 21 and 22. The subsequent three steps in Figures 2b and 2c and 2d progressively and increasingly bend and move the fold 16 close to the inner wall 10 at top dead center of the tube shape and simultaneously increasing and progressively bending and moving the lower extremities 21 and 22 upwards as shown. Thus, the tubular cross-section is reduced in its cross-sectional design.

With reference to figure 2e of the drawings, a final step of coincidence is carried out by bending the opposite side sections 14 and 15 inwards towards the center symmetry plane in order to be able to reduce the curved design of said two side sections and so that these occur within the radius or the outer diameter of the starting tube shape, and to lie within the inner diameter of the pipeline into which the end pipe liner L is to be inserted. A feature of this end colliding step is to bring together the two lower extremities 21 and 22 into a juxtaposed relationship to the center plane of symmetry and preferably closer together than the continuing pipe walls arising therefrom to the bends of the fold 16.

Referring to the apparatus for deforming this tube, it will be seen that there are four collapsing steps performed, four incremental progressive steps of folding the bottom section 13 of the tube shape upwards along the center plane of symmetry, and a fifth step of lateral inward collapsing. Each and all of these five steps involve bending and are mainly and not completely without stretching or elongation of the tube wall of the "tube sheet L in its transverse cross-section. Each collapsing step is carried out by forming devices, preferably in the form of forming rolls RI, R2, R3 and R4 followed by form rolls Sl and S2. It is these rolls that increasingly and progressively coincide with the extruded tube shape. In practice, the form rolls R1-R4 are the lowest and there are backing rolls Bl, B2 and B3 to store the tube shape as it is pressed onto by said rolls E1 -R4 As shown, the rollers R1-R4 and B1-B3 are located on separate and parallel horizontally arranged and transverse axes.

Backing roll Bl is arranged above the forming roll RI (see figure 4) and is characterized by its concave coil shape 25 at the center symmetry plane and fits the mainly semi-circular backing section 12 of the tube shape. Backing roller Bl has opposing flared side flanges which surround the starting shape of the side sections 14 and 15 of the tube shape.

Form roller RI (see figure 4) is characterized by its convex fold-initiating and forming circumference 27 at the center symmetry plane to press the tube wall upwards at the dead center. Form roll RI has opposed concave side flanges 21 which surround the starting form of the lower extremities 21 and 22 of the side sections 14 and 15. The circumferences of the roll flanges 26 and 28 are closely arranged to grip the pipe form between them.

Backing rollers B2 are arranged above and between the forming rollers R2 and R3 (see figure 3) and are characterized by their concave coil shape 35 at the center symmetry plane and fit with the mainly semi-circular backing section 12 to the tube shape. Backing roll B2 has opposing flared flanges 36, to a lesser extent than with roll B1, to embrace the shape of the side sections 14 and 15 of the tube shape.

Form roll R2 (see Figure 5) is characterized by its convex fold-forming circumference 37 at the center plane of symmetry to further shape the tubular wall upwards along said plane of symmetry. Form roller R2 has opposite concave side flanges 38 which surround the lower extremities 21 and 22 of the side sections 14 and 15. The circumferences of the roller flanges 36 and 38 are somewhat separated and control the tube shape between them.

The forming roll R3 (see figure 6) is characterized by its convex fold-forming circumference 47 at the center plane of symmetry to further shape the tubular wall upwards along said plane of symmetry. Form roll R3 has opposite concave side flanges 48, of smaller extent than for roll R2, which surround the lower extremities 21 and 22 of the side sections 14 and 15. The circumferences of the roll flanges 36 and 48 are somewhat separated and control the tube shape between them.

The backing roll B3 (see Figure 7) is arranged above the forming roll R4 and is characterized by its concave coil shape 55 at the center symmetry plane and fits the substantially semi-circular backing section 12 of the tube mold. The backing roller B3 has minimal side flanges 56 which surround the side sections 14 and 15 of the tube shape.

The forming roll R4 (see Figure 7) is characterized by its most sharply convex fold-forming circumference 57 at the center plane of symmetry to further shape the tubular wall along said plane of symmetry. Form roll R4 has opposite concave side flanges 58, but of less extent than for roll R3, which surround the lower extremities 21 and 22 of side sections 14 and 15. The circumferences of roll flanges 56 and 58 are arranged closely together to grip and control the pipe form between them .

The fifth and final collapsing step is performed by a pair of laterally arranged form rolls S1 and S2 which are located on opposite sides of the pipe mold as it exits from the form roll R4 (see Figures 8 and 9). The rollers Sl and S2 are to reduce the curved cross-section of the backing section 12 to the tube shape as shown. Consequently, the rollers S1 and S2 are arranged on separate and parallel vertical axes and they are characterized by a concave coil shape 60 of curvilinear design which increases in curvature from the top dead center from the starting full radius of the tubular shape to the smaller radius of the lower extremities 21 and 22. Sl and S2 have top and bottom flanges 61 and 62 which are circumferentially aligned to completely grasp the final collapsed and deformed tube shape and thereby establish the product tube coating L.

According to this invention, and which is best illustrated in Figures 8 and 9 of the drawings, the pipe form of the pipe coating L is finally folded onto a rail R arranged between the form rollers Sl and S2. The rail R has a cross-sectional design that fits with the inner walls of the side sections 14 and 15 and the lower extremities 21 and 22. Accordingly, and as clearly shown, the final cross-sectional design of the tube sheet L is established. In practice, the rail R has sliding engagement with the tube shape and has substantial longitudinal extent to enable a reduction in temperature to be achieved and to ensure that the tube takes on a firmer shape while maintaining the required cross-sectional design. Note in particular that the hourglass cross-section of the rail R which provides the aforesaid coincidence of the lower extremities 21 and 22 and brings them closer together in relation to the center plane of symmetry than the upstanding inner walls extending to the bends of the fold 16. In practice, the rail R optimal depending on the shape to be defined. If an exact curvature 16 is required, the rail R will help by keeping such a shape. This rail R will e.g. be necessary for joint fusion of the deformed pipe.

From the foregoing it will be seen that the forming of the tube shape is gradual and progressive (see figures 3 and 9) and from figure 3 it will be seen that temperature control is involved and the preferred material involved is a thermoplastic material. Accordingly, and as best shown in figure 3 in the drawings, it is the water nozzle 70 which emits tempered water to maintain the temperature of e.g. 99°C to soften the plastic material and ensure its bending properties. Other heat sources such as hot air or radiant heat can be used to achieve the desired temperature on the pipe, which must be above the crystallization point of the raw material. The nozzles 70 send hot water into the area of the form rolls RI to R4 and Sl and S2. Thus, the tube shape becomes plastic so that it can be shaped and bent to the desired deformed state. After the final forming of the pipe mold and its sliding engagement with the rail R, the molding temperature of the plastic pipe mold is reduced to the ambient temperature by water nozzles 71 which emit tempered water of a lower temperature to cool the end pipe coating L to e.g. 21°C. As shown in Figure 3, the tempered water is collected in a sump or pan 72 for recirculation. The cooling device C2 reduces the tube shape to ambient temperature on or when it is delivered from the rail R.

As shown in Figure 3 of the drawings, the rollers B1-B3, R1-R4 and S1 and S2 are free to rotate on the bearing 73 thereby allowing forward movement of the tube shape through the apparatus as described. However, when thin-walled coatings for large diameter pipes are processed, some material is required to assist the movement of the pipe form through the apparatus. Consequently, torque devices M in the form of motors M, electric or hydraulic, provide the necessary assistance (see figure 4). It must be understood that anti-friction bearings 73 are arranged with shafts 74 as shown in the drawings.

From the foregoing it will be understood that a tubular pipe liner L has been provided which has a reduced cross-sectional design so that it can be introduced into pipelines and then reformed to its original extruded cross-sectional shape, whereby it fits into the pipeline for which it is designed, as different circumstances require .

Because tubes in use are usually under pressure, it has been found that it is not necessary to heat the coating to its crystallisation point in order for the coating after reforming to remain frozen to its original generally cylindrical shape, if the coating is maintained under pressure for a longer time period. According to the present invention, that pressure can include the pressure of the liquid in the pipe when it is in normal use. Accordingly, after the interior of the pipe to be coated is cleaned by means of a conventional brush block, and the deformed coating is introduced into the pipe, the coating can be mechanically reformed to its original general cylindrical shape by means of a block and applied pressure. Accordingly, in this embodiment, the ends of the pipe coating are initially deformed as previously described and a block is introduced, preferably at the downstream end. The block can be conventional and consist of medium density foam. Before the initial introduction of the block, the ends of the pipe are closed and a fluid under pressure, e.g. air at a pressure between approximately 172 and 1030 kPa, depending on pipe size and length, is introduced behind the plug at the downstream end. In addition, a back pressure or vacuum pressure is provided at the upstream end of the pipe, e.g. on the order of about 34.5 to 276 kPa, again depending on the length and size of the pipe. Due to the difference in pressure applied to the block, the block moves from the downstream end of the pipe to the upstream end and mechanically reforms the pipe to its generally cylindrical shape as it moves between these ends. On arrival at the upstream end, the pressure behind the block is maintained over the entire pipe length and coating for a predetermined time interval, e.g. approximately 30 minutes. The pressure on the pipe lining is then removed and both end plugs and the block are also removed. Both • ends of the coating are then unfolded and said fluid operation reconnected.

It has been found that if the drive is reconnected and pressure is applied to the interior of the coating from operating fluid flowing through the coating within a predetermined time, e.g. within 24 hours of the completion of the coating installation, especially after the pressure has been removed from the coating, such pressures will ensure that the coating adheres to the walls of the existing pipe. It has also been found that over time, e.g. on the order of 3 or 4 weeks, then the stresses in the coating are released and the coating will remain generally cylindrical, even when the operating fluid under pressure is removed. Accordingly, the foregoing coating process may be applied to pipelines which are not normally pressurized provided that the pressure is maintained within the coating for the necessary predetermined time to release the stresses in the coating which tend to reform the coating to its original deformed shape. The time required is a function of the diameter, wall thickness and material of the coating and the degree of circularity required. For example, if an expanded but not cylindrical design of the coating in the pipe is acceptable, the period of time that the coating must be kept under pressure may be less than a week. On the other hand, such a time period should be of the order of 3 to 4 weeks if a perfect cylindrical coating is required. Consequently, the use of high-temperature fluids to trigger the stresses in the coating as previously explained is not necessary where the pressure can be maintained in the coating for a predetermined period of time after mechanical reforming. This technique is therefore particularly useful for recoating pipes where fluid under pressure is the usual fluid sent in the pipe.

A method for introducing the pipe coating into the pipe is shown in figures 10-15. The interior of pipe 80 may be cleaned by a conventional brush block 86. When block 86 is inserted into the upstream end of pipe 80, upstream and downstream manifolds 88 and 90 are attached to respective pipe flanges 82 and 84. To facilitate this connection, the manifolds provided with butted flanges 82' and 84', and connection is achieved via bolts or other suitable fasteners together with aligned openings in the respective flanges. A pull or control line 92 fed from a reel 94 through a vent hole 96 in the manifold 88 is attached to the rear end of the block 86 prior to closing the upstream manifold 88. The upstream manifold 88 has a closed end 98 which includes a removable plate and in which the an inlet valve 100 is fitted. In this start blocking operation, the valve 100 is connected via a line 102 to an air or liquid source 104 which is under pressure. The downstream manifold 90 is also equipped with an end plate on which an outlet valve 106 is mounted. A pressure gauge 108 monitors the pressure in the pipe.

Air or water under pressure is introduced through a valve 100 into the pipe behind the block 86 to push the brush block and pull the line 92 through the pipe to the downstream end thereof. During the block operation, the outlet valve 106 is set at approximately 690 kPa to ensure proper discharge of gas from the pipe as the block moves to the downstream end of the pipe. As the block 86 reaches the downstream end and moves into the manifold 90, the internal pressure in the pipe is gradually released and the manifolds 88 and 30 are opened and the block 86 is removed. The line 92 can then be pulled out and then attached to an assigned winch or reel 110 as shown in figure 11.

With further reference to Figure 11, the pipe section 80 is shown with the manifolds 88 and 90 open at their distal ends and with an original lightweight fish line 92 connected to a heavier haul or control line 112. Lines 92 and 112 are pulled through the pipe line 80 by the winch 110 which is adjacent to the downstream end of the pipeline 80 and manifold 90. The haul line 112 is unwound from a reel 114 at the upstream end of the pipeline section. When the correct pullline is pulled through the pipe section 80, it can be cut off to the upstream manifold 88 and then attached to the temporarily deformed U-shaped liner L, as more clearly shown in Figure 12. The pullline 112 is connected to the U-shaped liner L by of a suitable gripping arrangement shown schematically at 116 in Figure 12. The gripping device 116 is preferably of a radial expansion type to prevent destruction of the ends of the coating. As also shown in figure 12, the U-shaped coating L can be unwound from a warehouse or a supply drum S which is located next to the upstream manifold.

Figure 13 illustrates a cross section of the pipeline section 80 with the coating L in its final expanded form. This is shown in contrast to the cross-section of the pipe coating L in Figure 14 which illustrates this in its temporarily deformed U-shape. In Figure 15, a perspective view illustrates the temporarily deformed U-shaped coating L after this has been pulled through the pipe section 80 to be coated. Referring now to Figure 16, it can be seen that the coating L initially extends approximately to the open ends of the manifolds 88 and 90 to not only facilitate the expansion process, but also to leave sufficient coating to form radial flanges in a manner that shall be described in more detail in the following.

Figure 16 shows schematically the initial expansion of the coating L inside the pipe 80. When the coating is correctly positioned, a pair of mechanical expansion/packing sets are introduced into the coating from one end of the upstream and downstream manifolds 88 and 90. The packing/expander sets 120 and 122 are identical in every respect and therefore only one is described in detail. The downstream packer/expander 122 kit includes an inlet conduit or manifold 124 that is operatively connected to a closed boiler 126 through which hot fluid can be introduced into the coating via valve 128. The temperature of the fluid is monitored by a conventional gauge 130, while the pressure inside the the coating is monitored by a conventional pressure gauge 132. The inlet pipe 124 is connected via pipe extension 124' to a cylindrical packing set 134 consisting of conventional packing rings sized to seal the coating relative to the manifold 90 to prevent the escape of liquid from the coating through the manifold. A cylindrical wedge-like expander member 136 is provided with a tapered surface 138 and extends forward from the packing set and serves to force the coating end back into a cylindrical shape. A similar arrangement is provided at the upstream manifold 188 so that the coating L is initially expanded mechanically at both ends in the manner described above. The expander element 136 is equipped with an inner bore 140 which is operatively connected to the inlet conductor 124 and the closed boiler 126. It will thus be understood that the expander element 136 only starts the expansion process, while it facilitates the introduction of hot liquid through the bore 140 and into the coating 11 .

When the packing/expander sets 120, 122 are positioned inside the manifolds 88 and 90 so that the flanges 142 butt against corresponding flanges on the manifolds 88 and 90, hot water is introduced from the source 126 into the interior of the coating. Since the system is closed, the hot water can be brought to high temperatures without the formation of steam and in this initial step the hot water is introduced into the coating to raise the temperature of the coating above its crystal ice point. In the temperature raising step, a discharge valve 144 in the packing/expander set 120 allows hot water to flow continuously through the coating, with an initial pressure of approximately 7 bar. It must be understood that the time period required to reheat the coating to its shape memory temperature at the first pressure will depend on the diameter and length of the pipe to be coated.

When the coating has been heated to the crystallization-melting temperature, the U-shaped memory of the coating is removed and the coating tends to assume its original cylindrical shape. However, as mentioned earlier, since the inner wall of the tube 80 is not necessarily completely round, the now cylindrical coating may not necessarily conform exactly to the inner surface of the tube to be coated, especially over extended distances. Consequently, the pressure inside the coating is raised in a second step to about 15 bar to expand the coating L to substantially exact compliance with the inner surface of the tube 80, as shown. The process manifold is further equipped with an air outlet (air leak) which enables the air or liquid that may have been trapped between the coating and the original pipe to escape. This is another reason why the manifold is slightly oversized compared to the outer diameter of the coating.

Then the valve 128 is closed, the hot water supply 126 is disconnected and the hot water inside the pipe is drained. The packing/expanding sets 120, 122 are then withdrawn. While the coating is still hot, a conventional expansion block having a diameter substantially identical to the inside diameter of the expanded coating is inserted into the tube 80 and is pushed through the tube section while applying a radial force to the coating to squeeze away. any remaining air between the pipe and the coating so that the coating surface conforms 100$ to the inner surface of the pipe. The plug is preferably powered by a supply of cold water which more or less freezes the plastic to its final shape behind the plug and eliminates any air spaces between the coating and the pipe section.

While the expansion step is described with reference to the introduction of heated fluid from the source 126 at the downstream end of the tube 80 via the packing/expansion set 122, it will be apparent that the source 126 may just as easily be operatively connected to the upstream set 120. In this regard, manifolds 88 include , 90 and sets 120, 122 lead 124 which are equipped with the necessary inlets, outlets for monitoring devices, discharge valves and the like so that they are in fact interchangeable.

Reference is now made to Figures 20 to 22 where a schematic progression of the steps involved in the coating-unfolding process is illustrated. Thus, Figure 22 shows the expanded coating L extending past the pipe 80 with the manifold 88 removed. Typically, the coating is adjusted in accordance with predetermined and calculated data that establishes the length of coating necessary to produce a given size radial flange for pipes of various diameters. When the coating is adjusted, a first unfolding step begins where the coating end is heated, e.g. using an air gun to about 82 to 93°C, and the flange 48 is partially formed at an angle of about 10 to 21°C to the horizontal plane, as shown in Figure 21. The specific angle will depend on factors such as the diameter of the pipe, flange length, etc. Once the initial flare is formed at the coating end, it is rapidly cooled and then reheated to approximately 82 to 93°C. In a second expansion step, the partially expanded end is further deformed to engage the pipe flange 382 to form radial flanges 148 as illustrated in Figure 22, after which the coating is again rapidly cooled.

Figure 23 illustrates an example of a deployment tool for performing the first and second deployment steps as described above. A manually operated screw jack 150 is secured in at least two locations, preferably 180° apart, about the pipe flange 82. Thus, a pair of heavy duty bolts 152 extend between bolt holes formed in the flange 82 and a cross bar 154. The bar 154 is provided with a threaded opening 156 between the ends thereof to receive a threaded jack member 158 on which is mounted an expansion tool 160, a gasket set 162, a washer 164 and a nut 166 on one side of the crossbar 154, and a handle 168 on the other side of the crossbar. Clockwise rotation of the handle 168 will result in the unfolding tool 160 entering the coating end and unfolding this in a first unfolding step as previously described. The packing set 162 is used to prevent the coating L from creeping into the tube 80 during the expansion operation. After completion of the first stage of flare, the tool 160 is removed from the jack 158 and replaced by a second stage flare tool 170 shown in Figure 24. This second stage tool is nothing more than a raised cylindrical block which flattens the partial flare to full engagement with the pipe flange 82. In this respect, figure 25 shows an end view where the coating L is in its final expanded and expanded design with the tube 80.

In connection with the first and second unfolding stages, it must be understood that the speed at which the unfolding tools are brought into engagement with the coating end or ends must be related to the pipe diameter, temperature, etc. to prevent destruction of the end or ends. Thus, the spreading tools do not engage the coating end or ends until the temperature, which is monitored by conventional devices, reaches the predetermined level. In addition, during the expansion step the tools must remain in full pressure engagement with the coating end or ends during the respective cooling steps.

It must also be understood that the screw jack 150 can be hydraulically activated, especially for large diameter pipes.

Figure 26 shows several adjacent pipes 80, each of which has an individual coating applied in accordance with the method described above. The formation of radial flanges 148 on each coating section results in a continuous internal coating without exposing the pipe to the materials flowing through the pipeline. This is of course an alternative to introducing a simple continuous coating through several individual pipe sections, but with similarly effective results.

In accordance with another aspect thereof, there is provided an additional embodiment of a deformer generally designated 212. For the present purpose, it is to be understood that the coating L is fed to the deformer 212 at an equal temperature which is near or above the crystallization melting temperature, i.e. 113 °C for HDPE. The deformation apparatus 212 includes a pair of fixed positioning rollers 214 and 216 which are 90° apart and a pair of adjustable positioning rollers 218 and 220 which are 90° apart and opposite to the respective rollers 214 and 216. The adjustable rollers 218 and 220 are mounted on respective arms 222 and 224 for rotation about axes 226 and 228 which, as illustrated, are 90° apart. The arms and thus the adjustable rollers 218 and 220 are driven by respective suitable drive mechanisms 230 and 232 under the control of a computer C which will be described. The angular position of the rollers 218, 220 is also sensed and a signal proportional to the sensed diameter is fed to the computer C. The positioning rollers 214, 216, 218 and 220 also establish the axial centerline of the coating L as it passes through the deformer 212, and also feed the computer C with the diameter of the extruded tube.

Downstream of the positioning apparatus in the direction of axial pipe movement, there are arranged a pair of axially separated backing or storage rollers 234 and 236. Each of the rollers 234 and 236 is mounted for movement towards and away from the axis of the coating L by means of suitable devices, not shown, e.g. by means of suitable sliding devices under the control of a driven unit 238 and 240.

On the opposite side of the tube sheet L is arranged a deformation or penetration wheel or roller 242. The roller 242 preferably has a hollow rim which communicates with a hub through a series of hollow spokes 244 for the transfer and return of a heating fluid to the rim whereby the roller 242 can be heated to approximately the temperature of the plastic material that makes up the coating L that passes this station. Suitable fluid inlet and outlet lines are illustrated at 246 and 248, respectively. The roller 242 is mounted on an arm 250 which is pivotally mounted at one end for pivotal movement about an axis 252. A piston rod 254 to a power cylinder 256, preferably hydraulic, is coupled to the arm 250 whereby the arm 250 and consequently the wheel 242 carried by it can be displaced towards and away from the bearing L about the axis 252. Suitable structure, not shown, carries a motor, either a direct current motor or hydraulic motor, designated 258 to drive a draft arrangement 260 whereby the roller 242 can be rotated in the direction of the arrow designated 262. Thus, when the roller 242 is in engagement with the coating 262 and is rotated, the pulling arrangement will tend to displace the coating L in the downstream direction away from the extruder 210.

Downstream of the deformation roller 242, a rail 264 (Figure 30) is arranged which is carried at one end by suitable telescopic rods 266 mounted in the control device 268. The rail 264 is controlled by a preferably hydraulic power cylinder 270. The position of the rail 264 is controlled by the computer C in accordance with the diameter of the tube passing through the deformer 212.

A pair of support rollers 272 and 274 are mounted on opposite sides of the coating L, generally in the same manner as the positioning rollers 214 and 218. However, the rollers 272 and 274 are rotatable in planes slightly angled or offset from a common plane through the coating L so that their axes of rotation diverge to one side of the coating L, i.e. the side of the coating which has a generally semi-cylindrical design. The rollers 272 and 274 are also mounted on respective arms 276 and 278, and these arms are equipped with suitable power mechanisms 280 and 282 so that the storage rollers 272 and 274 can be moved towards and away from the coating and held in adjusted positions in relation to this.

Downstream of the rail 264, another pair of storage rollers 284 and 286 are arranged which are set at a similar angle in relation to the coating L as the rollers 272 and 274, but to a somewhat lesser extent. The rollers 284 and 286 are also mounted on arms which are carried for movement under the control of suitable powered mechanisms 288 and 290, whereby the rollers 284 and 286 can be moved towards and away from the covering L and held in adjusted positions relative thereto.

To deform the pipe using the deforming apparatus 212, the tubular coating L is arranged between the positioning rollers 214, 216, 218 and 220. The adjustable positioning rollers 218 and 220 are driven to engage the surface of the coating L as their angular position is sensed and a signal is fed to the computer which signal indicates the diameter of the pipe. Using this information, the computer feeds output signals to various downstream drive mechanisms to place the driven parts thereof in an appropriate position for the given diameter. E.g. the computer C signals the positioning devices 238 and 240 to drive the rollers 234 and 236 towards the coating axis to a position such that the side of the coating L which engages the rollers 234 and 236 will be elongated compared to the extension on the opposite side of the coating of the deformation roller 242. Correspondingly, the computer C signals the hydraulic cylinder 256 to displace the deformation roller 242 about the axis 252 of the movement path of the coating L, e.g. to the extent illustrated in Figure 29. It is to be understood that as the coating L passes between the deforming roll 242 and the backing or stocking roll 234, the coating is folded about a bilateral plane of symmetry through the axis of the tubular coating to form opposed curved side sections or loops 296 and 298 (Figure 29) on opposite sides of the plane of symmetry which also intersects the tip 300 of the fold applied to the coating by the deformation roll 242. In addition, heating fluid fed to the edge of the deformation roll 242 brings its temperature to match the temperature of the plastic material mass in the coating L during deformation. In this way, the temperature of the coating L is maintained substantially the same during the deformation process. It must be understood from Figure 29 that the side sections or loops 296 and 298 collapse or fold around the wheel 242 and that the coating is therefore transformed from its generally tubular or cylindrical configuration aligned with the dotted lines of Figure 29 into a generally U-shaped configuration .

The deformation process continues as the coating L extends from between the deformation roller 242 and the backing roller 234 by means of the paired rollers 272, 274 and 284, 286. More specifically, the first pair of rollers 272 and 274 are angled (Figures 29 and 30) toward the open side of the U-shaped coating and continues the bending or folding process and deforms the coating about the rail 264 as illustrated in Figure 30. The rail 264 is formed of a suitable material, such as Teflon, so that the coating L can immediately slide past the rail 264. Once past the rail 264 , a second pair of rollers 284 and 286 are used to essentially close the loops 296 and 298 against each other, as illustrated by the dashed line design in Figure 30. By maintaining the temperature of the plastic material of the coating L at or above the crystallization melting temperature to the material forming the coating and gradually folding the coating into its general U-shaped design, the coating will thus maintain itself in this direction ming on cooling while retaining the shape memory of its previous round or cylindrical design. Accordingly, the deformed generally U-shaped coating L, after it is cooled, be wound on a coil, and with the U-shaped design on the side when the coil is wound about a horizontal axis.

Before the process of installing the general U-shaped coating in a pipe as illustrated in Figures 31-34 will be described, certain tools used in connection therewith, including injection and outlet manifolds, together with the rounding tool, plug and end injectors, will be described. Reference is now made to Figure 35 where an injection manifold, generally designated 310, is illustrated, and which includes a steam inlet line 312 with a suitable valve 314, as well as temperature and pressure measuring instruments 316 and 318 respectively. The steam line is connected to a manifold body 320 as in in turn has an outlet 322 for sending steam into the coating L in a manner to be described. At one end of the manifold body 320 there is a water inlet 324 with an associated valve 326. An air inlet line 328 is connected to the manifold body 320 by means of an air pressure regulator 330. Manifold pressure and temperature measuring instruments are also arranged at 332 and 334.

Referring to Figure 36, the outlet manifold generally designated 336 includes a manifold body 338 having an inlet 340 for connection with the opposite end of the coating in a manner to be described. At one end of the manifold body 338 there is a pressure outlet valve 342 and at the opposite end a water outlet 344 and a valve 346 are therefore arranged. An air pressure outlet valve 348 is also arranged.

Referring to Figure 37, there is illustrated a combined rounding tool 350 and a plug 352. The rounding tool includes a generally frustoconical nose 354 having a concave cut-out opening 356 through its smallest diameter end and tapering from a sharp point 358 on one side thereof to the opposite side. The concave cutout 356 is designed to fit the proximate walls of the loops 296 and 298 of the generally U-shaped coating when the re-rounding tool 350 is inserted into the end of the deformed coating for the purpose of initiating expansion thereof to its round shape . On the opposite side of the rounding tool 350 from the tip 358, a pair of laterally separated rods 360 are arranged for insertion into the respective loops 296 and 298 of the generally U-shaped coating. The rods 360 taper from the end of the large diameter frustoconical rounding tool toward the truncated end. The base of the rounding tool 350 includes a pin 362 for receiving in a corresponding opening in a plug 352. The plug 352 is essentially a hollow cylinder having a tapered portion 364 towards one end. A steam inlet 366 is provided on the side of the plug 352 to pass steam into the interior of the plug 352. An outlet 368 is formed in the tapered side walls of the plug 352 to pass steam into the coating of the rounding tool in a manner and for reasons to be is described.

Reference is now made to Figure 39 where an end injector 370 is illustrated. The injector 370 consists of a cylindrical section which is closed at one end at 372 and which has a side inlet opening 374 for receiving steam.

Reference is again made to figures 31-34, where a pipe to be coated is illustrated, e.g. a sewer pipe P, arranged between manholes Ml and M2. To start the recoating process, the sewer line is first cleaned and inspected using conventional devices and any necessary repairs are carried out in the pipe. The pipe coating L is transported on a coil to the contractor's surroundings in a pre-measured length that exceeds the pipeline length between the manholes Ml and M2. At the contractor's site, the pipeline is transferred to a motorized trailer-mounted drum R for transport to the coating site. At the manhole Ml, the motorized drum 1 is set up so that the coating can be extracted from the top of the drum R. A curved guide 378 having several rollers 380 is placed in the manhole Ml to guide the coating L during its introduction into the pipe P. A pulling winch 382 is provided at the second manhole M2. A draft line is arranged through the sewer line P1 using conventional methods using a flow cleaner or a sewer parachute operated by air. The haul line is attached to the coating and the coating is fed into the pipe P by actuation of the winch 182 to pull and the motorized drum R to feed the coating through the pipe P substantially in a manner that avoids applying tension to the coating.

As the coating is introduced, a steam boiler B (Figure 31) mounted on a vehicle is activated and suitable air and steam connections are made with outlet manifold 336 at the second manhole M2. (Steam or cooking boiler B is illustrated in Figure 31 at manhole M1 for use in subsequent steps to be described.) When the liner L is introduced into the pipe P so that its ends extend past the ends of the pipe P, an end injector 370 is fitted over the protruding part of the coating in manhole M2, as illustrated in Figure 33. Steam is then introduced into the end injector 370 to soften the surrounding plastic material forming the coating L. Thermocouples 382 and 385 (Figure 31) are also located on opposite ends of the coating L In particular, the thermocouple 383 at the inlet end of the coating at manhole M1 is placed on the inside of the coating L, while the thermocouple 385 at the opposite end of the coating in manhole M2 is placed between the coating L and the pipe P, i.e. outside the coating rail. The thermocouples as shown in figure 31 are connected to a computer-assisted control CC which is carried by the vehicle where the boiler B is mounted. A control valve 386 and a flow meter system 388 are arranged between the boiler B and the injection manifold 310. The control valve 386 is arranged to control the steam flow. The flow meter system 388 feeds the computer CC with information regarding the flow rate of the vapor being fed to the coating L.

After steam is applied to the end injector 370, this is removed from the projecting end of the coating in manhole M2. The re-rounding tool 350 with applied plug 352 is inserted into the end of the liner at manhole M2 to initiate reforming of the deformed liner end into its round shape, and the engagement of the liner end between the tapered wall of the plug 352 forms a seal at this end of the liner. The end of the coating L at the manhole Ml is also equipped with a rounding tool 350 and the rounding is started in a similar way when the rounding tool is inserted. In particular, in the use of the tool 350, rods 360 are inserted into the loops 296 and 298 of the U-shaped coating L and the pointed end is inserted between the top of the U-shaped coating and the semi-circular base portion thereof. By forcing the re-rounding tool into the coating using hydraulic rams, not shown, the concave surface of the re-rounding tool causes the tip 300 (Figure 29) to shift outward while the remaining surfaces of the re-rounding tool 350 cause these surfaces to form a circular configuration. When introducing the rounding tool 350 and the plug 352 up to the transition between the cylindrical and tapered surface, the coating L is then clamped around the plug 352 which seals the ends of the coating about itself. The coating is now in a state where it can be blown out into the round shape.

To accomplish this, and with reference to Figures 31 and 34, the computer-assisted control CC opens control valve 386 and steam flows into the coating at manhole Ml. The CC computer is programmed to control the steam flow so that the temperature of the steam in the coating is raised to 116°C and the pressure to 69 kPa. The computer controls the flow of steam and maintains the steam in the coating during operation of the control valve at a temperature of 116" C and a pressure of 69 kPa for a predetermined period of time, ie on the order of 15 minutes. However, it must be understood that the coating temperature is below the crystallization melting temperature of the plastic material , e.g. 113°C for HDPE, during this predetermined time period despite the vapor temperature being higher than the crystallization melting temperature. However, it must also be understood that such a time period may vary for different pipe sizes. Suffice it to say that this temperature and this pressure is held for a period of time sufficient for the pressure to re-inflate the coating to its round shape over its entire length and the temperature, of course, facilitates the rounding of the coating by softening the plastic material.The temperature of the plastic coating material during the predetermined time period is intentionally kept below the crystallization melting temperature of r the ear coating material so that elongation in the circumferential direction of the coating is essentially eliminated. That is, if the temperature of the coating material was initially increased rapidly to a temperature above the crystallization melting temperature, then such a high temperature would stretch the coating in a circumferential direction so that when the coating approached its round shape, there would be too much not-yet-rounded material for to continue the rounding process. That is, it has been found that if the material was initially heated to a temperature above the crystal in the serring temperature, it will bend or form an inwardly directed rib or protrusion rather than assuming a round shape. By keeping the temperature of the material below the crystallization melting temperature and applying sufficient pressure, i.e. about 10 psig, the coating material will not elongate and it will swell to the round shape against the walls of the pipe P.

When the coating has assumed this round shape, the temperature of the steam fed to the coating L is raised to an even higher temperature above the crystallization melting temperature, i.e. approximately 127-129.5°C. The pressure is also raised to 172 kPa. This pressure and this temperature are similarly maintained for a predetermined period of time. More specifically, the temperature is maintained for a period of time such that the temperature of the plastic material sensed by thermocouple 383 approaches the temperature of the steam fed at this end to the coating and the temperature sensed by thermocouple 185 in manhole M2 reaches 70$ of the temperature sensed by thermocouple 383 at manhole Ml. That is, it is sufficient for about 70% of the mass of plastic material to reach the crystallization melting temperature to remove the U-shaped memory and re-establish, activate and bring back the cylindrical memory. In other words, about 7056 of the coating wall thickness will be at a temperature above the crystallization melting temperature and this is sufficient to reactivate the memory of the round shape and deactivate the memory of the U shape. When these temperature conditions are reached, the computer begins the cool-down process.

Specifically, the computer CC cuts off the steam supply to the coating L and opens the air valve in the injection manifold 310 to introduce air into the coating. However, the pressure inside the coating L is maintained at 172 kPa during the cooling. When the temperature reaches a third predetermined temperature, e.g. about 93°C, water is then injected into the coating from the injection manifold 310 to cool the coating to a temperature that is a predetermined percentage of the ambient temperature at which point the pipe coating is substantially complete. The various connections to the coating are then disconnected and the water is drained from the coating. The ends of the coating which extend past the ends of the tube P are then cut off. It must be understood that no adhesive or other type of material to attach the coating to the pipe is necessary, mainly since the outer diameter of the coating is somewhat larger than the inner diameter of the pipe. Thus, the pressure to the coating will tend to return it to its normal round shape due to its round shape memory which is sufficient to create such friction in the pipe as to prevent or arrest any movement of the coating relative to the pipe.

With reference to Figure 40, a graph of pressure and temperature is illustrated on the ordinate axis as a function of time on the abscissa axis and which illustrates the installation of the pipeline according to the previous description. The solid lines refer to the temperature scale on the ordinate axis, while the dotted lines refer to the pressure scale on the ordinate axis. It will be seen that during the start-up phase the steam generator over time generates a steam pressure of approximately 116°C which is fed to the coating at point R. At the same time pressure is built up inside the coating to 69 kPa as indicated at point S. The temperature and pressure conditions are maintained in a predetermined time period, of the order of 15 minutes, until at points T and U respectively, where the temperature and pressure are raised to 127-129.5°C and 172 kPa respectively, and these latter points are named V and W. During the raising of temperature and pressure to the points R and S respectively, and maintaining temperature and pressure through the respective points T and U, it will be seen that the steam temperature at the inlet end of the coating as measured by thermocouple 383 rises along the curve X, while the temperature of the coating at the downstream end of this at thermocouple 385 rises at a slower rate, as indicated by Y. Consequently, while temperature and pressure are maintained for a predetermined time, the actual temperature to be the bed material does not reach the crystallization melting temperature before the temperature and pressure are raised to the respective points V and V/.

When the steam temperature is raised to point V, i.e. 127-129.5°C and the pressure is raised to point W, i.e. 172-179 kPa, the temperature of the coating continues to increase as indicated by curves X and Y until a time when the thermocouple 183 registers a coating temperature at the inlet which approaches the vapor temperature and is above the crystallization melting point, as indicated by Z. The temperature on the outside of the coating at the opposite end of the coating is indicated by Z' and it is to be understood that this temperature is a predetermined percentage of the temperature Z at the inlet end of the coating. When the two conditions are satisfied, a predetermined percentage, ie preferably about 70% of the mass of plastic material forming the coating, has reached the crystallization melting temperature at which time the U-shaped memory is smeared out and the circular memory is activated to maintain the coating in a round design inside the tube. At this point, the cooling period starts where air is expelled to start cooling the coating. Water is then injected when the coating at its inlet end reaches a predetermined temperature, i.e. on the order of 93° C illustrated at point K.

Claims (5)

1. A method of in-situ installation of an elongate hollow liner (L) in a substantially horizontally extending, generally cylindrical pipe (80), wherein the liner (L) is formed of thermoplastic material having a cross-section changed at a shape memory activation temperature from a substantially cylindrical cross-section with an original outer diameter substantially comparable to the inner diameter of the pipe to be lined, to a reduced cross-section having a reduced cross-sectional dimension to be able to draw the liner (L) into the pipe (80), where the liner is maintained by its reduced cross-section by itself without external assistance, which liner of the altered cross-section has a predetermined wall thickness and is inserted into the pipe so that the end portions of the liner extend beyond opposite ends of the pipe; characterized by subsequent steps: (a) sealing the end portions of the liner (L) beyond the opposite ends of the tubes to seal the inside of the liner at its opposite ends; (b) after the step of sealing the liner and while maintaining the liner (L) sealed, substantially conforming the shape of the liner to the inner wall of the pipe while substantially maintaining the original predetermined wall thickness by (1) injecting a heated fluid into and through the sealed liner; (2) pressurizing the interior of the liner to a first predetermined pressure above atmospheric pressure by means of the heated fluid and (3) reheating the liner to a predetermined temperature below the activation temperature by heat transfer from the heated fluid to the liner, whereby the liner returns substantially to its original or reduced cylindrical cross-section and takes shape substantially similar to the inner contour of the tube; (c) increasing the temperature of the liner to a second temperature above the activation temperature; (d) increasing the pressure in the liner to a second predetermined pressure above the first predetermined pressure to conform the shape of the liner fairly precisely to the inner wall surface contours of the pipe; and (e) while the liner is still hot, a cooling fluid is introduced into the liner for flow through to fix the liner into final shape conforming to the inner wall of the pipe. 2. Method according to claim 1, characterized in that the end portions of the liner which extend beyond the opposite ends of the pipe are partially expanded with mechanical means inserted in the end portions of the liner so that the expanded end portions of the liner approach the original cylindrical shape of the liner. 3. Method according to claim 1, characterized by a step of maintaining the liner at the first temperature and the first pressure for a predetermined time period, then increasing the temperature in the liner to the second temperature above the activation temperature. 4. Method according to claim 3, characterized in that the liner is made of a polyethylene material, and the first pressure is in the order of approximately 69 kPa and the second temperature and the second pressure are in the order of 126.6-129.6 °C and approximately 172.3 - 179 .3 kPa respectively. 5 . Apparatus for installing a folded substantially U-shaped liner (L) in a pipe (80) wherein the liner has a radially inwardly extending fold (16) extending along its length, wherein the liner (L) has been drawn into and through the tube (80), wherein the liner extends outwardly from opposite ends of the tube; characterized by means (120,122) for mechanically initiating expansion of the liner at opposite ends thereof comprising a pair of substantially cylindrical members (136), each member (136) having a wedge shape at one end defining a substantially inclined surface (138) between its opposite sides, one side extending axially beyond the opposite side to define a tip along the opposite side for contact within an outwardly extending end of the substantially U-shaped tube liner (L) between one side of the liner and its inwardly extending fold (16 ) to reshape the casing end into a substantially cylindrical configuration; each of the wedge-shaped elements has packing means (134) for sealing the cylindrical end of the liner (L) after its initial expansion to cylindrical shape, one of the elements (136) having an internal bore for connection to a fluid source for introducing fluid into the liner (L); and means (124) for supplying heat into the casing (L) including passing heated fluid through the bore to raise the temperature of the casing.