GB2270963A

GB2270963A - Pipe removal and replacement

Info

Publication number: GB2270963A
Application number: GB9318982A
Authority: GB
Inventors: Eric Albaret; Michel Aplagnat-Tartet
Original assignee: SADE Compagnie Generale de Travaux dHydraulique SA
Current assignee: SADE Compagnie Generale de Travaux dHydraulique SA
Priority date: 1992-09-25
Filing date: 1993-09-14
Publication date: 1994-03-30
Anticipated expiration: 2013-09-14
Also published as: ES2087012B1; NL193729C; BE1007542A3; NL193729B; GB2270963B; NL9301630A; FR2696227B1; FR2696227A1; GB9318982D0; ES2087012A2; ES2087012R

Abstract

The apparatus comprises a traction cable (8) to be pulled and having a calibration slug (18) fixed thereon at a distance from its end that is greater than length (L) of lead pipe (3) to be extracted and anchor members (19) distributed in regularly spaced-apart groups behind slug 18; each member (19) includes a forwardly projecting anchor tooth (20) and the teeth within a given group are uniformly spaced apart angularly; an abutment (22) to bear against rear end (6) of pipe 3 is also fixed to cable 8 at a distance (D) from slug 18 that is slightly less than length (L) of pipe 3. As cable 8 is pulled through pipe 3 by drum 10 of winch 11, slug 18 opens up pipe 3 making it round. When slug 18 reaches near end 5 of pipe 3 abutment 22 is mounted on cable 8 by clamp 31 to abut end 6 and free end of a replaceable plastics pipe is coupled to cable 8 by sleeves 33, 35. The winch runs as abutment 22 abuts end 6 to tension cable 8 causing wedges 19 to dig into pipe 3 for its bodily removal. <IMAGE>

Description

A METHOD AND APPARATUS FOR REMOVING A LEAD WATER PIPE FROM THE GROUND WITHOUT BREAKING IT, AND FOR SIMULTANEOUSLY REPLACING IT WITH A PLASTICS PIPE The present invention relates to a method and apparatus for removing a lead water pipe from the ground without breaking it, and for simultaneously replacing it with a plastics pipe, e.g. a polyethylene pipe.

A first known technique consists in clearing and cutting the street end and the house end of the pipe and then in pulling on one of its ends in the hope that the entire length of pipe will be extracted. Very often the pipe breaks and replacing it becomes difficult, lengthy, and expensive.

A second known technique consists of inserting a cable in the pipe, in fixing the cable to one end thereof, and in pulling the cable from the opposite end.

In this case also, results are not encouraging, since the lead pipe tends to become crushed and torn, and some of it remains stuck in the ground.

An object of the present invention is to achieve extraction of such a pipe without significant damage.

To this end, and in accordance with the invention, the extractor apparatus comprises a traction cable having a calibration slug fixed thereon at a distance from its end to which traction is to be applied that is greater than the length of the lead pipe to be extracted and, behind the slug, anchor members that are distributed in regularly spaced-apart groups; each anchor member including an anchor tooth that projects forwards, the teeth of the members constituting a single group being uniformly distributed angularly; and an abutment of sufficient size to bear against the rear end of the lead pipe, the abutment being fixed to the cable at a distance from the calibration slug that is slightly less than the length of said pipe.

In a particularly advantageous embodiment, each anchor member is a circularly symmetrical wedge whose outer conical surface is eccentric relative to a cylindrical hole provided for passing the cable, at least one fixing member such as a screw being mounted in the thick portion of the wedge to secure it to the cable.

Each group comprises two anchor members that are spaced apart from each other and that are diametrically opposite.

The above-mentioned abutment is a cup-washer designed to be threaded onto the cable and to be held in place thereon by a cable clamp mounted behind it.

Dismountable fixing means are capable of connecting the end of the cable situated behind the abutment to the free end of the plastics pipe.

The invention also provides an extraction method constituting an application of the apparatus in question.

The method consists: in disengaging and sectioning the street end and the house end of a lead branch pipe; in inserting a cable into the lead pipe from the house end and in extracting it from the street end to enable said cable to be wound onto a winch; in clamping a calibrating slug onto the house end of the cable and in clamping suitably distributed and oriented anchor members to the cable behind the slug; in using the winch to pull the cable so that it becomes tensioned in front of the slug, thereby enabling the slug to calibrate the lead pipe, while the cable remains slack behind the slug and entrains the anchor members along a sinuous path so that they are prevented from digging into the lead; in mounting an abutment on the cable so that it bears against the house end of the lead pipe before the calibration slug is disengaged from the street end of the lead pipe;; in tensioning the cable so that the anchor members dig into the lead; and in pulling the cable so that said anchor members pull out the lead pipe together with the cable, said assembly being wound onto the drum of the winch as it is extracted from the ground.

The method also consists in fixing a plastics pipe behind the abutment at the house end so that while the cable is being pulled to extract the lead pipe, the plastics pipe follows the lead pipe and takes its place.

Various other characteristics and advantages of the invention appear further from the following detailed description.

An embodiment of the apparatus of the invention and ways of performing steps in the method constituting an application thereof are shown by way of non-limiting example in the accompanying drawings.

In the drawings: Figure 1 is a diagrammatic section through the ground in which a lead pipe to be extracted is situated, the section showing a first step in the implementation of the method; Figure 2 is a view analogous to Figure 1, showing a prior step that may be required; Figures 3 and 4 are views analogous to Figure 1 relating to subsequent extraction steps, terminating in final extraction of the lead pipe; Figure 5 is a view analogous to Figure 1 showing how a replacement plastics pipe is installed; Figure 6 is a diagrammatic view showing the apparatus being disengaged from the extracted lead pipe for the purpose of subsequent reuse; Figure 7 is a section through the coupling between the cable and the rodding used in the step prior to the method, as shown in Figure 2;; Figure 8 is a section through the calibration slug used during the first step of the method as shown in Figure 1; Figures 9 and 10 are sections through the lead pipe showing the conical wedges of the apparatus while the cable is being drawn in the pipe-extraction direction, respectively with the cable in the slack state and in the tensioned state; and Figure 11 is a diagrammatic section through the abutment of the apparatus, its cable clamp, and the means for coupling the plastics pipe to the cable.

In ground 1, there are buried a mains pipe 2, and branch pipes 3 for water supply purposes. Each branch pipe 3 runs from the mains pipe 2 and terminates at a meter situated in a basement or in a manhole.

The method consists in digging a trench 4 to disengage the mains pipe 2 and the branch pipe 3 so as to extract and then cut off the "street" end 5 of the branch pipe. The method also consists in disengaging the other or "house" end 6 and in cutting it off, either directly in the basement of the house, or else in the manhole or in a ditch 7 dug for this purpose.

The apparatus for extracting the lead pipe 3 after its ends have been disconnected in this way comprises firstly a cable 8 for passing along the pipe from its house end 6 (Figure 1) until a sufficient length thereof projects into the trench 4. The projecting end 9 of the cable is intended for winding on the drum 10 of a traction winch 11 which is suspended from a hoist 12 mounted under a frame 13 placed astride the trench.

The structure 14 of the traction winch 11 bears against a slab 15 pressed against the side of said trench in which the pipe 3 opens out. The traction winch 11 automatically takes up an appropriate position, with the cable of the hoist 12 sloping to compensate, and with the hoist rotating so that the last turn being wound on the drum 10 of the traction winch is always situated facing the pipe 3.

If it is impossible or too difficult to run the cable 8 along the pipe 3 from its end 6, then a "Malacca cane" rodding 16 (Figure 2) may be used. The rodding is then inserted into the pipe 3 from its street end 5.

When it comes out into the ditch 7 at the house end 6 of the pipe, it is connected to the cable 8 close to the end 6 by means of a coupling 17. Thereafter the rod is pulled by hand from the trench 4 until the cable 8 reaches the trench, as shown in Figure 1. The coupling 17 is removed and the rodding 16 is recovered.

Regardless of whether the cable 8 is installed by means of rodding or otherwise, a calibration slug 18 is mounted on the cable close to the end 6 and then anchor members 19 are fixed at intervals along said cable.

Each member 19 has a front projecting anchor tooth 20 extending to a distance "d" from the axis 21 of the cable 8 that is greater than the inside radius "r" of the pipe 3 when said cable is under tension (Figure 10); in contrast, so long as the cable is slack (sinuous configuration of Figure 9), the distance "d" becomes less than the radius "r" and because force is not being applied to the member in question on its side opposite from the tooth, the tooth does not have any tendency to wedge in the pipe. In addition, the members 10 are distributed at intervals along the cable in closetogether groups of two, three or more members that are directed so that their teeth 20 are uniformly spaced angularly within a group, while different groups are spaced apart from one anther by a distance that is greater than the spacing between contiguous members within a group.

Under such conditions, when the cable 8 is drawn in the slack state in the direction of arrow F (Figure 3), the members 19 are free to move without their teeth 20 catching against the inside wall of the pipe 3. However, when the cable 9 is pulled in the direction of arrow F (Figure 10) while it is in the tensioned state, then the teeth of these members dig into the lead at close together points that are uniformly distributed angularly and that serve to secure the pipe to the cable 8.

In this embodiment, each group of spaced-apart wedges comprises two diametrically-opposite wedges 19.1 and 19.2 at a small spacing from each other whereas the spacing between groups is greater. Thus, in the example shown, the wedges within a group are about 20 cm apart whereas the closest-together wedges of two adjacent groups are spaced apart by about 80 cm.

Naturally, each group may have a larger number of wedges: for example it may have three wedges at 1200 intervals from one another, or it may have four wedges that may be diametrically opposite in pairs, or that may be at 900 intervals.

As shown in Figure 11, the drive abutment 22 mentioned above is a cup washer whose outside diameter is no greater than the outside diameter of the lead pipe 5 and whose inside diameter is at least as great as the diameter of the cable 8. This abutment is held in place on the cable by a cable clamp 31. The clamp may be a sleeve suitable for clamping to the cable by means of screws 32. In the example shown, the screws are shown as being three in number by way of non-limiting example, and they are shown as being distributed along a single generator line. The overall size of the cable clamp 31 must be such as to ensure that it cannot catch on the ground as it follows the lead pipe while it is being extracted.

Naturally the traction abutment could be of any other type, e.g. a mandrel which is clamped onto the cable by screwing and which has a thrust shoulder facing the lead pipe.

Behind the cable clamp 31, releasable fixing means 33 are provided for fixing a plastics pipe 34, e.g. made of polyethylene, to the house end of the cable 8. These means 33 comprise an outer sleeve 35 and an inner sleeve 36 for engaging in and around the plastics pipe 34. The inner sleeve 36 has a projecting cylindrical shoulder portion 37 in which at least one locking screw 38 is installed for coupling said sleeve to the cable 8, which cable passes along a central hole 39 of the sleeve.

Advantageously, two screws 39 may be provided that converge towards each other. Furthermore, the coupling between the two sleeves 35 and 36 and the plastics pipe 34 may be provided by means of a member such as a pin, a screw, or the like passing through holes 40 and 42 formed through said elements 34 to 36.

The outer sleeve 35 could be replaced by a collar, tight binding, or the like. The important point is that the overall size of the sleeve or other means must be such as to enable it to follow the lead pipe 5 while the pipe is being extracted and without catching on the ground.

As shown in Figure 7, the coupling 17 is cylindrical and has rounded ends. It defines a bore 43 having a shoulder and serving to receive the rodding 16 and the cable 8, each of which is secured by means of respective clamping screws 44 and 45.

Similarly, and as shown in Figure 8, the calibration slug 18 is cylindrical and rounded at its ends. However, whereas the coupling 17has an outside diameter that is smaller than the inside diameter of the lead pipe 5 in order to be able to slide easily therealong, the outside diameter of the calibration slug 18 is equal to or slightly greater than the inside diameter of the lead pipe 5. The calibration slug 18 is fixed to the cable 8 by means of at least one clamping screw 46 passing through the slug 18 to secure it to the cable passing therethrough (two screws are shown in the present example).

As mentioned above, the method consists: in inserting a cable 8 into the lead pipe 3 whose ends 5 and 6 have previously been sectioned, which cable may be inserted either directly or by means of rodding 16 to which it is connected by a coupling 17; in mounting a calibration slug 18 on the cable 8 close to the end 6 of the lead pipe 3, and then behind the slug, mounting anchor wedges 19 in a distribution as described above; in winding the projecting end 9 of the cable 8 onto the drum 10 of the traction winch 11; in operating the winch so as to pull the cable 8 in the direction of arrow F, thereby causing its calibration slug 18 to open up the lead pipe 3 and make it round;; the cable and its string of wedges 19 follow on behind the slug as shown diagrammatically in Figures 3 and 9 with the cable occupying a slack and sinuous configuration such that the wedges 19 cannot dig into the lead; in stopping the winch 11 once the calibration slug has come to within a short distance "1" of the end 5 of the pipe 3, which distance can be identified by a colored mark on the cable (Figure 3); in mounting the traction abutment 22 on the cable 8 close to the end 6 of the pipe 3, and in locking it in place by means of the cable clamp 31; in coupling the free end of a plastics pipe 34 to the cable 8 by means of the sleeves 35 and 36; ; in running the winch 11 again, thus having the initial effect of tensioning the cable 8 once the abutment 22 bears against the end 6 of the pipe 3, and of digging the wedges 19 into the lead, so that the cable is rendered integral with the pipe along its entire length, and subsequently having the effect of extracting the pipe 3 by winding it together with the cable 8 and its wedges 19 onto the drum 10 of the traction winch 11 (Figure 4) while simultaneously causing it to be replaced by the plastics pipe 34 (Figure 5); in removing the drum 10 that has been loaded in this way and in unwinding the assembly 3, 8, 19, e.g. by causing it to pass through a calendar 47 (Figure 6) until the straightened pipe 3 comes into abutment against a block 48 through which the cable 8 is passed and wound onto the drum 49 of a winch 50; ; in operating the winch 50 to extract the cable 8 and its collection of wedges 19 by pulling in the direction of arrow G which is opposite to the direction of arrow F (Figure 6), i.e. in the direction that causes the wedges to disengage easily from the lead; and in recovering the lead and in releasing the assembly 8, 18, and 19 for subsequent use in extracting another pipe.

Naturally, the extraction apparatus can be implemented without the coupling means 33, particularly when the lead pipe is not being replaced by a plastics pipe in exactly the same location.

Claims

1/ Apparatus for extracting a lead water pipe from the ground without breaking it and for simultaneously replacing it with a plastics pipe, e.g. made of polyethylene, characterized: in that it comprises a traction cable (8) having a calibration slug (18) fixed thereon at a distance from its end to which traction is to be applied that is greater than the length (L) of the lead pipe (3) to be extracted and, behind the slug, anchor members (19) that are distributed in regularly spaced-apart groups; in that each anchor member (19) includes an anchor tooth (20) that projects forwards, the teeth of the members constituting a single group being uniformly distributed angularly; and in that an abutment (22) of sufficient size to bear against the rear end (6) of the lead pipe is fixed to the cable at a distance (D) from the calibration slug that is slightly less than the length (L) of said pipe.

2/ Apparatus according to claim 1, characterized in that each anchor member (19) is a circularly symmetrical wedge whose outer conical surface (23) is eccentric relative to a cylindrical hole (24) provided for passing the cable (8), at least one fixing member such as a screw (29) being mounted in the thick portion of the wedge to secure it to the cable.

3/ Apparatus according to claim 1 or 2, characterized in that each group comprises two anchor members (19) that are spaced apart from each other and that are diametrically opposite.

4/ apparatus according to any one of claims 1 to 3, characterized in that the above-mentioned abutment is a cup-washer (22) designed to be threaded onto the cable (8) and to be held in place thereon by a cable clamp (31) mounted behind it.

5/ Apparatus according to any one of claims 1 to 4, characterized in that dismountable fixing means (33) are capable of connecting the end of the cable (8) situated behind the abutment (22) to the free end of the plastics pipe (34).

6/ Apparatus according to claim 5, characterized in that the dismountable fixing means (33) are constituted by an outer sleeve (35) and an inner sleeve (36) designed to be engaged with and fixed to the plastics pipe (34), the inner sleeve (36) being extended by a cable clamp (37, 38) for fixing to the cable (8).

7/ A method of extracting a lead pipe (3) from the ground without breaking it and of simultaneously replacing it with a plastics pipe (34) e.g. made of polyethylene, constituting an application of the apparatus according to any one of claims 1 to 6, and characterized in that it consists: in disengaging and sectioning the street end (6) and the house end (5) of a lead branch pipe (3); in inserting a cable (8) into the lead pipe (3) from the house end (6) and in extracting it from the street end (5) to enable said cable to be wound onto a winch (11); in clamping a calibrating slug (18) onto the house end of the cable (8) and in clamping suitably distributed and oriented anchor members (19) to the cable behind the slug;; in using the winch (11) to pull the cable (8) so that it becomes tensioned in front of the slug (18), thereby enabling the slug to calibrate the lead pipe (3), while the cable remains slack behind the slug and entrains the anchor members (19) along a sinuous path so that they are prevented from digging into the lead; in mounting an abutment (22) on the cable (8) so that it bears against the house end (6) of the lead pipe (3) before the calibration slug (18) is disengaged from the street end (5) of the lead pipe (3); in tensioning the cable (8) so that the anchor members (19) dig into the lead; and in pulling the cable (8) so that said anchor members (19) pull out the lead pipe (3) together with the cable, said assembly being wound onto the drum (10) of the winch (11) as it is extracted from the ground.

8/ A method according to claim 7, characterized in that it also consists in fixing a plastics pipe (34) behind the abutment (22) at the house end so that while the cable (8) is being pulled to extract the lead pipe (3), the plastics pipe (34) follows the lead pipe and takes its place.

9/ A method according to claim 6 or 7, characterized in that when it is not easy to insert the cable (8) in the lead pipe (3), the method further consists in sliding flexible "Malacca cane" rodding (16) along the pipe, with the street end of the rodding projecting from said lead pipe, mounting a coupling (17) to the house end of the rodding with the coupling being fixed to said rodding (16) and to said cable (8), in particular by means of screws, and then in pulling the rodding so as to install the cable in the lead pipe, and once the cable extends beyond the pipe, in disconnecting said rodding.

10/ Apparatus according to claim 1, substantially as described with reference to the accompanying drawings.

11/ A method according to claim 7, substantially as described with reference to the accompanying drawings.