Hydraulic and earth engineering – Subterranean or submarine pipe or cable laying – retrieving,... – Repair – replacement – or improvement
Patent
1997-10-08
1999-11-16
Bagnell, David
Hydraulic and earth engineering
Subterranean or submarine pipe or cable laying, retrieving,...
Repair, replacement, or improvement
405154, 405156, 138 97, 138 98, 294 981, E02F 510, B66C 146
Patent
active
059845821
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a method of extracting a hollow member laid in the earth.
Pipes, for example for conducting drinking water, can become leaky after decades of use, or have other drawbacks, so that it becomes necessary to replace them by new pipes. Such pipes for domestic connections consisted in the past, among other materials, also of lead. Therefore it is also appropriate or even prescribed for health and environmental reasons to replace the lead pipes by pipes of another material, preferably polyethylene (PE). For this purpose the lead pipes should be withdrawn from the earth and the new pipes inserted into the earth in their place. When however the front end of the lead pipe is connected to a traction element and then attempts are made to withdraw the lead pipe, due to the low tensile strength of the lead it is unavoidable that the pipe will immediately rupture. Again, it is not possible to force the lead pipe out of the earth by connections at the rear end, as it is not sufficiently pressure-resistant, and would immediately deform.
SUMMARY OF THE INVENTION
It is therefore the object of the present invention to indicate a method of extracting a hollow member laid in the earth, which is accessible at both its open ends, in which neither rupture nor deformation of the hollow member occur.
This object is achieved according to the invention by the features indicated in the characterizing part of claim 1. Advantageous further developments of the method according to the invention will become apparent from the secondary claims.
By virtue of the fact that a hose, which may be pressurized by an internal pressure, is introduced in the unpressurized state into the hollow member over at least a portion of its length, that the hose is internally pressurized, pressing against the internal wall of the hollow member with an internal pressure, and then that, maintaining the internal pressure, the hollow member is withdrawn from the earth by means of a frictional and positive connection in its longitudinal direction by means of the hose itself and/or by means of a traction element introduced into the hollow member along with the hose, said traction element being pressed by the internal pressurization of the hose against the internal wall of the hollow member, the necessary tension is exerted over the entire length of the hose introduced into the hollow member, so that rupture of the hollow member is excluded.
The hose and if necessary the traction element preferably have an extensibility in the longitudinal direction which is greater than the extensibility of the hollow member. Therefore the hose is expanded at the beginning of the traction procedure. This achieves a situation in which the pipe is not suddenly set in motion all at once over its entire length, but the movement begins at the traction end of the hollow member and then progresses, expanding the hollow member, or opening any sleeve connections which may be present, over its entire length as far as the other end. In this way the tensile forces necessary to set the hollow member in motion can be considerably reduced. In order to achieve this effect, it may also be sufficient to provide the hose only with sections spaced apart in the longitudinal direction, and whose extensibility in the longitudinal direction corresponds to that of the pipe.
Should the tensile forces transmissible over the hose not be sufficient, it is recommended to introduce into the hollow member, along with the hose, a traction element, said traction element being pressed against the internal wall of the hollow member by means of internal pressurization of the hose, and being used in this condition in order to extract a hollow member.
There is preferably coupled, behind the rear end in the extraction direction of the hollow member, a new hollow member, which is simultaneously drawn into the earth along with extraction of the hollow member. Thus extraction of the old hollow member and introduction of the new hollow member take place in one working ste
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Bagnell David
Lee Jong-Suk
LandOfFree
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