Cutting – Other than completely through work thickness or through work... – Scoring
Reexamination Certificate
1999-09-09
2001-08-21
Bray, W. Donald (Department: 3725)
Cutting
Other than completely through work thickness or through work...
Scoring
C029S403300, C081S009510, C083S873000, C083S874000, C083S425200
Reexamination Certificate
active
06276250
ABSTRACT:
The present invention relates to a method and apparatus for separating a pipe from a cable or the like used to pull the pipe from the ground.
In the past lead piping has been used extensively, particularly in water distribution systems. However, lead piping is no longer acceptable to such applications for health risk and environmental reasons. It has therefore become necessary to replace lead piping.
A variety of different methods and apparatus are known for extracting lead piping from the ground. In particular, it is known to pull piping from the ground using a cable or the like which is inserted into the pipe and which may be provided with gripping means along its length which distribute the pulling force over the length of the pipe or may be fitted with a device which imparts the pulling force to one end of the pipe. Examples of such pipe extraction apparatus are described in British patent application no. 9422919 (publication no. 2285297).
Inevitably such apparatus can become so firmly jammed in a pipe that its removal therefrom can be difficult if not impossible. Thus, the pipe removal apparatus often has to be discarded along with the pipe after use.
It is an object of the present invention to obviate or mitigate the above problem.
According to a first aspect of the present invention there is provided a method of separating a pipe from an elongate flexible element used to pull the pipe from the ground, the method comprising drawing the flexible element past separating means which splits the pipe along its length as it passes to thereby strip the pipe from the flexible element.
The flexible element may be a cable or the like fitted with gripping means as mentioned above. The present invention thus provides a way of removing the cable e.t.c. from a pipe so that it does not need to be discarded but rather can be re-used.
The method may include the step of scoring the pipe along its length and splitting the pipe along one or more score lines to strip the pipe from the flexible element.
Since the wall thickness of any given pipe may not be uniform along its length, an incision intended to score the pipe may actually cut through the pipe wall in places and this possibility is intended to be covered by the term “score”. The term “score” is thus to be interpreted accordingly throughout this specification.
Any suitable means could be used to score the pipe and more than one score line may be made along the length or the pipe. Similarly, a variety of different means could be used to strip the weakened pipe from the flexible element.
The method can be performed at the site at which the pipe is extracted from the ground. This would allow immediate re-use of the cable e.t.c. to extract another pipe. Alternatively, piping extracted from the ground could be transported off site to a central location at which the method is performed to recover the cable e.t.c.
Preferably a winch is used to draw the pipe past the separating means and the pipe is stripped from the flexible element upstream of the winch so that only the flexible element reaches the winch.
In one preferred manner of performing the invention in which the pipe is separated from the flexible element on site as it is pulled from the ground, the winch provides the means for pulling the flexible element and pipe from the ground.
The pipe may emerge from the ground into an excavation. The winch may, however, be situated above ground level and the pipe re-directed out of the excavation to the location of the winch.
Any scoring operation may be performed within the excavation, before the pipe is directed to the winch, or alternately after the pipe has been directed towards the winch. In the latter case the pipe may be scored at or above ground level to permit ready monitoring of the operation.
A wheel or roller may be provided in the excavation to direct the flexible element/pipe towards the winch, the direction of the pipe changing as it is pulled around a part of the circumference of the wheel/roller by the winch/flexible element. The roller/wheel diameter is preferably maximised to reduce deformation of the pipe and is preferably profiled to match the diameter of the pipe.
The wheel/roller may be provided with a scoring edge around its circumference (e.g. a circumferential blade) to score the pipe as it passes around the wheel/roller.
As mentioned above, the method according to the present invention may be performed away from the site at which a pipe is removed from the ground. For instance the pipe/flexible element composite may be coiled onto a winch drum or the like at the pipe removal site and then transported to a central pipe/flexible element separation site.
Thus, in one manner of performing the invention the flexible element/pipe is drawn from a drum or roller (for instance a winch drum onto which the pipe/flexible element has been wound at the pipe removal site) by a winch and the stripping (and any scoring) operations are performed as the flexible element/pipe passes from the drum/roller to the winch. Alternatively a scoring operation may be performed at the pipe removal site before the pipe/flexible element is taken to the pipe/flexible element separation site, in which case only the stripping operation need be performed at the pipe/flexible element is passed from the drum/roller to the winch.
When performing the method in the manner described in the above paragraph, the pipe is preferably straightened prior to the scoring and/or stripping operation.
When performing the method at the site of removal of the pipe from the ground, the flexible element may be pulled by a winch from another winch which is actually used to pull the flexible element/pipe from the ground. For instance, where the pipe emerges from the ground into an excavation a winch may be situated within the excavation and operated as a capstan feeding the flexible element/pipe to a second winch which is situated above ground level. Scoring and splitting operations may be performed between the two winches.
As mentioned above, the operation of splitting the pipe from the flexible element may be performed in a variety of ways. For instance, in one preferred manner of performing the invention, the splitting operation is performed by pulling the flexible element past a splitter member which bears against the internal wall of the pipe and forces the pipe in a direction away from the flexible element thereby causing the pipe to split. The splitter member preferably has portions on diametrically opposite sides of the flexible element so that opposite sides of the pipe are forced in opposite directions. For example, the splitter member may be a tapered member (e.g. a cone) through which the flexible element is pulled so that the pipe passes over the outside of the splitter member and is thereby forced to split apart so that it falls away from the flexible element.
The splitter member may be provided with one or more blades to cut the pipe wall. In this case it may not be necessary to first score the pipe before splitting it from the flexible element.
Alternatively, the splitting operation may be performed simply by pulling the pipe at an angle to the flexible element so that the flexible element breaks through the weakened pipe wall.
As mentioned above, any suitable means could be used to score the pipe. For instance, a pair of knife edge wheels may be used to score the pipe at diametrically opposed positions. Such wheels may preferably be supported by a mounting which is itself substantially fixed in position but which supports the wheels with freedom of translational movement to accommodate transverse deviation in motion of the pipe.
The wheels may be powered to rotate with a tangential speed greater than the speed of travel of the pipe.
In all the above described ways of performing the invention the pipe may be scored along its length (although this might unavoidably lead to the pipe being cut in places as a result of irregularities in the thickness of the pipe wall). This is advantageous as it reduces the risk of damage to the flexible element and any pipe grip
Ayling John David Kenneth
Raphael Jeremy Nathaniel Nieto
Bray W. Donald
Michael Best & Friedrich L
United Utilities PLC
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