WO2006136794A1

WO2006136794A1 - Improvements in or relating to pipelines and method of installation thereof

Info

Publication number: WO2006136794A1
Application number: PCT/GB2006/002226
Authority: WO
Inventors: Kenneth Latimer Scott
Original assignee: Kenneth Latimer Scott
Priority date: 2005-06-21
Filing date: 2006-06-19
Publication date: 2006-12-28
Also published as: GB0612052D0; GB2427450A; JP2008546964A; GB2427450B; GB0512619D0

Abstract

A pipe section (10) is disclosed in which opposite ends (16, 17) are provided with interengagement means (18, 24) by which adjacent sections can be joined together and held against axial separation. The opposite ends of the pipe sections are inclined with respect to the normal to the pipe section axis X-X so that adjacent pipe sections can be inclined with respect to one another by turning one about its longitudinal axis. Sealing means (47) are provided to seal a length of pipe formed from a number of such pipe sections against ingress or egress of fluid, and a pipe installation method comprising thrusting individual pipe sections forward, engaging them together and rotating about longitudinal axes to drive the pipe assembly around a curve are also described.

Description

IMPROVEMENTS IN OR RELATING TO PIPELINES AND METHOD OF

INSTALLATION THEREOF

The present invention relates to pipelines generally, and in particular to improved pipelines having means for securing adjacent pipe sections together.

Traditionally, pipes for conveying fluids have been made in lengths or sections each provided with means at the ends for joining the pipe sections to adjacent such pipe sections. Various techniques have been used to achieve this objective. For example, steel or cast iron pipes are conventionally provided with radial flanges at each end, each having a plurality of holes in a circumferential array around the pipe mouth, which flanges are placed face-to-face and bolted or riveted together to join two adjacent pipe sections. In more recent times metal pipes have been joined by welding and plastic pipes by solvent welding. For this latter purpose it is usual for the pipes to have sleeves or collars surrounding the outside to provide an added area of face-to-face contact for the solvent to provide an adequate fluid-tight seal. Land drains, traditionally made of clay, have been provided with an enlarged end portion the interior diameter of which matches the exterior diameter of the main length of the pipe so that an end of the main length can be fitted into the enlarged portion. Cementitious material is then used in the space to seal the junction against the escape of fluids carried by the pipeline. All of these pipe section connection techniques have one feature in common, namely that they secure the pipe sections together firmly, sometimes providing a fluid-tight seal, but always forming a junction which does not allow adjacent pipe sections to move in relation to one another, especially not to rotate about their respective longitudinal axes.

In order to drain areas of land it has been traditional to introduce land drain pipelines underground to receive surface runoff and carry it away to a suitable destination, usually a watercourse. The drainage of large urban areas likewise involves the installation of underground drainage pipes, these frequently being laid underneath roadways, partly because roadways have a special need for drainage and partly because the construction of roadways involves excavation which facilitates the burying of underground pipelines.

Over an extended period of time, however, especially where ground movements may have taken place, or tree roots may have caused local pressures such underground pipelines may become fractured. The weight of traffic running over the surface of a piece of ground bearing a drainage pipeline may also result in compaction and damage to the pipeline. Pipeline damage may take the form of deformation of the original shape of the pipe (this is particularly prevalent in pitch fibre pipes widely used in the latter part of the twentieth century) and fracture (which is a particular problem of clay pipes and other rigid materials). Deformation frequently leads to the problem of a restricted lumen and the possibility of aggregation and blockage, whilst fracture results in problems of leakage.

The drainage systems in many urban areas now have an extensive requirement for reinstatement. The cost of excavating along the line of a drainage pipe to form a trench allowing replacement pipe to be installed in the same way as the original pipe was installed is, however, extremely expensive, time consuming and disruptive, especially when the pipes have been laid along roadways. One way in which reinstatement of failed pipes has been achieved without the need for extensive trench digging involves the formation of successive spaced pits along the length of a failed pipeline, and the introduction of a pipe liner into the interior of the pre-existing pipe, by drawing or pushing a fresh pipe, usually made of a plastics material, into the pre-existing pipe. This technique has a number of advantages, the most significant of which is the avoidance of extensive trench digging and the consequent disruption, but also certain limitations. The distance between successive pits has to be relatively small because of the frictional forces involved in forcing a liner into the interior of the pre-existing pipe, and this is exacerbated if there is even the slightest curve or bend in the pipe, hi some circumstances, however, there are quite significant bends in pipes and until now the only way in which reinstatement could be achieved was by complete excavation of the area of the bend and replacement of the faulty pipe. One common problem where main drains have been laid along the centre of a roadway, lies in the fact that the feeder pipes from drains placed along the sides of the roadway. For drainage purposes roadways are cambered so that the surface water runoff takes the shortest route from the centre of the road to the sides and then along drainage gutters parallel to the road curb leading to gratings over gullies from which the water can then run back towards the centre of the roadway through a pipe which then bends through 90 degrees to drop into the main drain. This configuration is used in order to ensure that water arriving from the roadway can securely enter the main drain without risk of fluid within the drain flowing back into the gully and causing contamination (although, at times of flood, when the main drain is overloaded, this does, in fact, sometimes occur).

The present invention seeks to provide a novel means by which at least some of the above-identified problems can be resolved or at least mitigated.

According to one aspect of the present invention, therefore, there is provided a pipe section for use in forming a pipeline, in which opposite ends of a generally cylindrical wall are provided with interengagement means by which adjacent sections can be joined together and held against axial separation while allowing relative rotation about a longitudinal axis extending at least approximately along the length of the pipe section. In a preferred embodiment of the invention the said interengagement means are integrally formed as part of the body of the pipe section itself.

The present invention also comprehends a pipe section as defined above in which the interengagement means do not necessarily allow relative rotation of adjacent pipe sections, or in which, even if such relative rotation is possible, it may not be practical, for example because of the junctional forces involved.

Preferably, in a pipe section as defined hereinabove, the said interengagement means may be shaped to snap-engage and retain the said adjacent pipe sections together by the resilience of the material of which the snap-engagement means are made. Obviously, if the snap-engagement means are integrally formed as in the first embodiment referred to above, the material of the pipe section itself must be such as to allow such snap-engagement.

The said snap-engagement means may be formed within the wall thickness of the pipe section itself.

In order to allow for the possibility of producing curved pipe assemblies, at least one end of the cylindrical wall of the pipe section may be inclined at a non- orthogonal angle with respect to the longitudinal axis of the pipe section, such that adjacent interengaged pipe sections can be oriented with the respective longitudinal axes at and angle to one another by selecting the relative orientation therefore about respective longitudinal axes. The body of the pipe may be injection moulded from plasties material.

Ih order to form pipe sections which may be oriented to form a rectilinear or a curved pipe assembly, the opposite ends of the pipe section may be inclined either in the same direction with respect to the longitudinal axis of the pipe section or in opposite directions. Likewise, the inclination may be at the same angle (that is in terms of magnitude) with respect to the longitudinal axis of the pipe section or at different angles.

In a presently preferred embodiment of the invention the snap-engagement means comprise an annular groove or channel in one end of the pipe section and an annular bead or ridge in the other, the groove or channel having a re-entrant form and the bead or ridge being joined to the body of the pipe section by an annular wall portion of lesser thickness than either the bead or ridge or the wall of the body of the pipe section. This may be expressed as a narrowing or neck in cross section.

The cross sectional shape of the groove or channel, like that of the bead or ridge, may be asymmetric whereby to exert a constant resilient force once snap- engagement has taken place.

According to another aspect of the present invention, a method of lining a preexisting pipe or a passage having a curved section or bend along its length, is provided in which a pipe assembly comprising a plurality of pipe sections joined end-to-end is formed by snap-engaging together a plurality of pipe sections as hereinabove defined, orienting the individual pipe sections such that the overall pipe assembly is substantially rectilinear, introducing the pipe assembly into the passage or a pre-existing pipe and advancing it until the leading pipe section encounters the adjacent end of the curved section or bend of the passage or pre- existing pipe, rotating the pipe assembly about its longitudinal axis until the longitudinal axis of the said leading pipe section is inclined with respect to the longitudinal axis of the pipe assembly as a whole and substantially in the plane of the curved sectional bend, further advancing the pipe assembly until the next adjacent pipe section engages the curved sectional bend in the passage or pre- existing pipe, further rotating the pipe assembly about its longitudinal axis until the longitudinal axis of the said next adjacent pipe section is inclined to the longitudinal axis of the pipe assembly as a whole and substantially in the plane of the curved section or bend, and repeating the advancing and rotating steps until the pipe assembly is sufficiently advanced around the bend in the passage or the pre- existing pipe.

The present invention also comprehends a pipe assembly comprising a plurality of pipe sections as hereinbefore defined engaged together end-to-end.

Further, the invention comprehends a method of assembling a pipeline comprising the steps of:

i) locating two pipe sections as hereinbefore defined in an end-to-end relative juxtaposition, ii) locating the said interengagement means thereof in operative relationship, iii) engaging the said interengagement means of the said two pipe sections to retain the two said pipe sections together, and iv) locating further said pipe sections in an end-to-end relation with successive end pipe sections of the thus-formed assembly until an assembly of sufficient length is formed.

The present invention may also be considered to comprehend the use of a pipeline assembly of successive interengaged pipe sections to reinstate a pre-existing pipeline having a curved section or bend in it.

Various embodiments of the present invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a schematic side view of a first embodiment of the invention;

Figure 2 is a schematic side view of the embodiment of Figure 1 illustrating it in a different configuration; Figure 3 is a similar enlarged sectional view of a part of the embodiment of

Figures 1 and 2;

Figure 4 is a similar schematic side view of a second embodiment of the invention; Figure 5 is a schematic side view of the embodiment of Figure 4 showing it in a second configuration;

Figure 6 is an enlarged sectional view of a part of a further embodiment of the invention; Figure 7 is a sectional view through a roadway illustrating the drainage arrangements beneath it; and

Figure 8 is an enlarged view of a detail of the drainage arrangements of Figure 7 illustrating the manner of which a pipe assembly such as that illustrated in Figures 1 and 2 may be used to form or line a bend; and Figures 9 A and 9B are respective enlarged sectional views of an improved sealing and engagement arrangement suitable for use with the pipe section of the invention.

Referring first to Figures 1, 2 and 3, there is shown a pipe assembly generally indicated 10 comprising a plurality of identical pipe sections 11 which are shown in more detail in Figure 3. Each pipe section 11 comprises a generally cylindrical wall 12 having plane inner and outer cylindrical surfaces 13, 14 respectively. The pipe section 11 has two opposite ends 15, 16 each of which is generally planar and inclined at an angle α to the radial plane orthogonal to the axis X-X of the cylindrical wall 12. The angle α may typically be in the region of 3 to 5 degrees, but may be larger than this for special purposes. Each of the end walls 15, 16 is inclined oppositely with respect to the radial plane from the other. This forms a trapezoidal outline in axial section as can be seen in Figure 3. Figure 1 shows an assembly of such sections each adjacent section being oriented with its inclined end walls 15, 16 turned to face in the opposite direction from that of the next adjacent section so that, as can be seen in Figure 1, the overall pipe assembly 10 is generally rectilinear.

The end wall 15 of the pipe section 11 has a circumferential ridge 17 which, in cross section, has a generally circular mushroom head 18 with a neck portion 19 formed by two undercut sides 20, 21. As can be seen in Figure 3 the mushroom head 18 is asymmetric, with a bias towards the radially outer part of the pipe section 11.

The opposite end 16 of the pipe section 11 is correspondingly and oppositely inclined to the radial plane orthogonal to the axis X-X, by the same angle α as the inclination of the end 15, and in its end face 21 there is formed a circumferential groove 22 having a narrow neck 23 and an enlarged fundus 24. The shape of the circumferential groove 22 substantially matches the cross sectional shape of the ridge 17 in the opposite end of the pipe section 11.

The neck 23 of the groove 22 is, effectively, formed by two narrow wall portions 25, 26 which themselves have a wider end 25a and a narrower neck portion 26a and 25b, 26b capable of resiliently flexing so that, in order to join two pipe sections 11 end-to-end it is simply necessary to place the ridge 17 at the entrance or neck portion 23 of the groove 22, and to exert an axial force urging the two pipe sections together, in which case the resiliently flexible narrow neck portions 25b, 26b of the walls 25, 26 allow these to flex outwardly to permit the mushroom head 18 of the ridge 17 to enter the fundus 24 of the groove 22. Once snap-engaged together the two pipe sections are held securely, but relative rotation about the axis X-X can take place providing sufficient force is applied to overcome the frictional resistance of the circumferential engagement of the ridge 17 and the groove 22.

It will be appreciated that a pipe section 11 such as that illustrated in Figures 1 to 3 has a relatively longer circumferential sector exemplified by the wall section A of Figure 3, and a relatively shorter circumferential sector exemplified by the wall section B of Figure 3. When adjacent pipe sections are positioned with their respective circumferential sectors A, B in register, as shown in Figure 3, the axis X-X of each adjacent pipe section is inclined by an angle 2α with respect to the axis X-X of the adjacent pipe section. However, if the respective circumferential sectors A, B are placed opposite one another such that in adjacent pipe sections the long circumferential sector A is in register with the short circumferential sector B of the adjacent pipe section 11, then the pipe assembly adopts a rectilinear configuration as illustrated in Figure 1.

Figures 4 and 5 illustrate an alternative embodiment in which, rather than opposite end walls being oppositely inclined with respect to a radial plane, the opposite end walls are inclined at the same angle with respect to a radial plane and in the same direction. Ih axial section, therefore, the pipe sections have a parallelogram shape rather than a trapezium shape as in the embodiment of Figures 1 to 3, but like the embodiment of Figures 1 to 3, when the adjacent pipe sections are turned about their respective axes they may be positioned to adopt a rectilinear configuration as shown in Figure 4 with all the inclined faces lying in parallel planes, or a curved configuration as shown in Figure 5. This embodiment, however, only allows two adjacent pipe sections to form a curve since, by turning a third pipe section it is only possible to achieve a curve in an opposite or reflex sense. This may be of convenience, for example, where there is a kink in a pipeline which has to be lined.

Figure 6 shows a further embodiment of the invention having orthogonal end walls with snap-engagement ridge and groove corresponding to those of Figure 3 and which, therefore, will not be described in detail herein. By providing orthogonal end walls the pipe sections of Figure 6 can be snap-engaged together to allow relative axial forces both of compression and traction to be applied between the two adjacent sections. In this embodiment, of course, relative angular orientation about the longitudinal axis of each pipe section will not change the rectilinear configuration of the pipe assembly. For this reason pipe sections formed in accordance with this embodiment may be rather longer than those illustrated in Figures 1 to 3, and the snap-engagement may be used simply as a means of interconnecting adjacent pipe sections end-to-end rather than as a means of achieving pipe bends.

Figure 7 shows a typical situation in which a pipe bend may be needed when relining an aged pre-existing pipe. In Figure 7 there is shown a roadway surface 30 having, as is common, a camber or curve between a high crest 31 and a lower margin 32. At the margin 32 there is a longitudinal gutter 33 defined between the margin 32 of the roadway 30 and a curb 34 standing between the roadway 30 and a walkway or pavement 35.

At intervals along the gutter 33 are located respective gratings 36 each of which overlies a respective gully 37 communicating with an underground pipe 38 extending towards the centreline of the roadway 30 under the road surface, and terminating in a right angle bend 39 to open into the upper part of a main drain 40. If an attempt is made to reline the drain pipe 38 by introducing and advancing a pipe liner this can only reach to a point indicated C in Figure 7 at the commencement of the right angle bend 39. hi order to complete this bend a pipe assembly such as that illustrated in Figures 1 to 3 may be employed as illustrated in Figure 8. Here, the right angle bend 39 in the pre-existing pipe is illustrated with an assembly of pipe sections 11 (only the first two of which are illustrated) which have been introduced and advanced into the pipe 38.

Whatever the angular orientation of the pipe sections 11 about the longitudinal axis X-X of the pipe assembly a point on the peripheral rim of the leading end of the leading pipe section 11 will eventually come into contact with the radially outermost wall of the pipe bend 39. In Figure 8 this is illustrated as being a point on the shorter sector B but it could equally be any point around the circumference. When the advancing movement of the pipe assembly is arrested by this contact, it is simply necessary to turn the pipe assembly about the axis X-X. Because of the inclination of corresponding contacting faces of adjacent pipe sections 11 the entire assembly will tend to rotate about the axis X-X. However, the leading end pipe section 11 will only turn to the point where the leading end of the longer circumferential sector A contacts the curved side wall of the pipe bend 39, beyond which the pipe section cannot turn since to do so would involve the leading end of the longer circumferential sector A passing out through the wall of the pipe section 39. As a consequence the interface between the first pipe section 11 and the next adjacent pipe section 11 is subject to shear forces which allow the two elements to rotate about the axis X-X with respect to one another so that the leading pipe section can adopt the position illustrated in broken outline in Figure 8. At this point further advancing movement of the pipe assembly moves the next adjacent pipe section into the same position as the first pipe section had been when it engaged the curved pipe wall 39. Further rotation of the pipe assembly will thus lead to a corresponding relative rotation between the second pipe section 11₂ and a third pipe section H₃, and so on until the entire pipe assembly has been brought into a curved configuration such as that illustrated in Figure 2 occupying the interior of the pipe bend 39.

Because it is valuable to be able to provide a secure fluid-tight seal when two adjacent pipe sections are engaged together the arrangement of Figure 9 may be utilized. This Figure shows, on an enlarged scale and in section the cooperating wall parts of two adjacent pipe sections, similar to those of Figure 3. In Figure 7, however, a pipe wall 40 has a groove 41 with a narrow neck 42 into which a correspondingly shaped ridge 43 with a mushroom head 44 and a narrow neck 45 can be snap-engaged. The circumferential ridge 43 may be in all respects identical to the ridge 17 in the embodiment Figure 3. The groove 41, however, differs in that it has a V-section channel 46 in the bottom part or fundus of the circular- section main portion 41 of the groove. In use a sealing ring 47 is fitted into the mouth of the V-section channel 46 and is retained in position by friction. Upon snap-engagement of the ridge 43 into the groove 41 sealing ring 47 is pressed more deeply into the V-section channel 46 and presses against the crown 47 of the mushroom head 44 with an interspace 49, 50 respectively on either side thereof. The inclination of the side walls of the V-section channel 46 assist in driving the sealing-ring 47 towards the mushroom head 44 so that whichever side of the wall experiences the higher pressure (for example, if the interior of the pipe is under pressure or the exterior of the pipe is under pressure) this pressure, entering the interspace 48 between the two wall portions urges the sealing ring 47 more tightly into the interspace 49 or 50 thereby increasing the sealing pressure and ensuring a firm seal.

Claims

1. A pipe section for use in forming a pipeline, in which opposite ends of a generally cylindrical wall are provided with interengagement means by which adjacent sections can be joined together and held against axial separation while allowing relative rotation about a longitudinal axis extending at least approximately along the length of the pipe section; and means for sealing the said pipe sections against escape or ingress of fluid at the interengagement sections.

2. A pipe section as claimed in Claim 1, in which the said interengagement means are integrally formed as part of the body of the pipe section itself.

3. A pipe section as claimed in Claim 1 or Claim 2, in which the said interengagement means are shaped to snap-engage and retain the said adjacent pipe sections together by the resilience of the material of which the snap-engagement means are made.

4. A pipe section as claimed in Claim 2 or Claim 3, in which the said snap- engagement means are formed within the wall thickness of the pipe section itself.

5. A pipe section as claimed in any preceding Claim, in which at least the end of the cylindrical wall of the pipe section is inclined at a non-orthogonal angle with respect to the longitudinal axis of the pipe section such that adjacent interengaged pipe sections can be oriented with their respective longitudinal axes at an angle to one another by selecting the relative orientation thereof about respective longitudinal axes.

6. A pipe section as claimed in Claim 5, in which the opposite ends of the pipe sections are inclined in the same direction with respect to the longitudinal axis of the pipe section.

7. A pipe section as claimed in Claim 5, in which the opposite ends of the pipe section are inclined in opposite directions with respect to the longitudinal axis of the pipe section.

8. A pipe section as claimed in Claim 6 or Claim 7, in which the opposite ends of the pipe section are inclined at the same angle (magnitude only) with respect to the longitudinal axis of the pipe section.

9. A pipe section as claimed in any preceding Claims, in which the interengagement means comprise an annular groove or channel in one end of the pipe section and an annular bead or ridge in the other, the groove or channel having a re-entrant form and the bead or ridge being joined to the body of the pipe section by an annular wall portion of lesser thickness than either the bead or ridge or the wall of the body of the pipe section, the groove or channel itself having a recess for receiving a sealing element.

10. A pipe section as claimed in Claim 9, in which the cross sectional shape of the groove or channel axis and that of the bead or ridge is asymmetric.

11. A pipe section as claimed in any preceding Claim, in which the body of the pipe is injection moulded from plastics material.

12. A pipe section as claimed in Claim 9, or Claims 10 or 11 as described therein, in which the sealing element is a compressible bead, strip or ring enagagable in the said recess.

13. A pipe assembly comprising a plurality of pipe sections as claimed in any of Claims 1 to 11 engaged together end-to-end.

14. A method of lining a pre-existing pipe or a passage having a curved section or bend along its length, in which a pipe assembly comprising a plurality of pipe sections formed end-to-end is formed by engaging together a plurality of pipe sections having interengagement means, introducing the pipe assembly into the passage or a pre-existing pipe and advancing it until the leading pipe section encounters the adjacent end of the curved section or bend of the passage or pre- existing pipe, rotating the pipe assembly about the longitudinal axis of the leading pipe section until the longitudinal axis of the said leading pipe section is inclined with respect to the longitudinal axis of the next adjacent pipe section of the pipe assembly, further advancing the pipe assembly until the next adjacent pipe section engages the curved section or bend in the passage or pre-existing pipe, further rotating the pipe assembly about the longitudinal axis of the said next adjacent pipe section until the longitudinal axis of the said next adjacent pipe section is inclined to the longitudinal axis of the nearest member of the pipe assembly, and repeating the advancing and rotating steps to advance the pipe assembly around the bend in the passage or pre-existing pipe.

15. A method of assembling a pipeline comprising the steps of: i) locating two pipe sections as claimed in any of Claims 1 to 11 in an end-to-end relative juxtaposition, ii) locating the said interengagement means thereof in operative relationship, iii) engaging the said interengagement means of the said two pipe sections to retain the two said pipe sections together, and iv) locating further said pipe sections in an end-to-end relation with successive end pipe sections of the thus-formed assembly until an assembly of sufficient length is formed.

16. The use of a pipeline assembly of successive interengaged pipe sections to reinstate a pre-existing pipeline having a curved section or bend in it.