METHOD AND DEVICE FOR REPLACING DAMAGED PIPES BURIED IN THE GROUND

Abstract: Method for replacing damaged pipes, e.g. sewers, buried in the ground and extending between two shafts or access wells, lengths of a replacement pipe being descended one after the other through one of the shafts. The pipe lengths (1) are descended in the shaft placed on a pressure medium hose (5) by means of which a breaker head (3) is powered for disintegrating the existing damaged pipe (B) while being pulled through it and entraining the first pipe length (1). The pipe lengths are descended through the shaft to a position adjacent a previously descended pipe length, whereupon the end surfaces of the two pipe lengths are heated to a temperature in the vicinity of the melting point and are welded together. The invention also relates to a device for heating the end surfaces of the pipe lengths (1) for carrying out the method. The device consists of two plate members (12, 13) which are interconnected by a hinge (11) and which, when brought together, form a heating plate (6) for heating the pipe end surfaces to be welded together, said heating plate (6) having a central hole (18) for allowing passage of the compressed-air hose (5).

Description: METHOD AND DEVICE FOR REPLACING DAMAGED PIPES BURIED IN THE GROUND The present invention relates to a method and a device according to the preambles of the method claim and the device claim. In this■ technical field, many new types of pipes have come into use over the past years in connection with so-called relining because of the highly increased costs for the excavation and backfilling work required when laying new pipes. In general, these pipes have been of short length and, thus, have given rise to many joints, this making the pipes far more expensive than conventional ones. Further, in relining using such pipes, these have been pressed into an existing pipeline, a consequent problem being that the joints have not been able to withstand the stresses applied to them. It is therefore an object of the present inven¬ tion to provide a simple and inexpensive relining method which does not necessitate any additional ex¬ cavation and backfilling operations as compared with the present-day technique for repairing pipes buried in the ground with the relining technique. Another object of the invention is to make it possible in this type of work, to use conventional standard-length PEH or PEM pipes which can be cut into suitable lengths and descended through narrow shafts or wells. A further object of the invention is to achieve completely jointless and straight piping. These objects are achieved with a method and a device as recited in the claims. With the method and the device according to the invention, it is possible by using ordinary standard— length polyethylene pipes, to reduce the costs for relining by up to two thirds of the costs presently incurred for the same work. Also, the method according to the invention yields considerably improved piping as compared with the methods hitherto used. Practical tests have shown that the method using a low-frequency breaker head can also be used in heavy-duty sewers without causing damage to adjacent piping, e.g. water pipes and the like, by the vibrations from the break- ing operation.-Thus, " the method of the invention is highly useful. The invention will be described in more detail hereinbelow with reference to the accompanying drawings in which: Fig. 1 schematically illustrates the method of the invention; and, Fig. 2, on a larger scale, shows one embodiment of the inventive device for carrying out the method. Fig. 1 schematically illustrates the method accord- ing to the invention in which a pipe of thermoplastic, e.g. PEH or PEM, is descended through a shaft or an access well 2 in pipe lengths 1 placed on a compressed- air hose 5 used for powering a breaker head 3 containing a pneumatic hammer, and extending from a compressor 4. At the bottom of the access well, the pipe lengths 1 are arranged one after the other in a fixture (not shown) for coaxial alignment with each other. For joining together the pipe lengths 1, a heater 6, which will be described in more detail hereinbelow, is suc- cessively placed between the pipe lengths for heating the ends of the pipes facing each other to a temperature in the vicinity of the plastic deformation temperature of the pipes, whereupon the heater is removed and the pipes are brought together and, thus, are butt-welded to each other. The above-mentioned breaker head serves to disin¬ tegrate the .piping 3 to be replaced r which extends between two wells 2 and 9. To this end, the breaker head has such dimensions that when vibrating at a low frequency, it bursts the existing piping B into pieces while being pulled forwards by a wire 7 which is fixed to the front end of the beaker head and passes through the piping B and, via a guide pulley 8 disposed in the well 9 located further ahead on the piping B, is drawn by means of a winch disposed at ground level. The pipe length 1 first descended through the well 2 is fixedly anchored to the rear end of the breaker head by means of bolts or the like. In this manner, the pipe lengths successively welded together will be advanced through the passage which is made by the breaker head 3 and where the damaged piping B previously lay. When the old piping has been re¬ placed in its entirety, the junctions are sealed in a conventional manner, e.g. with polyurethane foam. At the points along the repaired piping where so-called service lines should be connected to it, there is arranged a temporary access shaft, which is obtained by digging a hole in the ground at the site of junction and progressively lowering therein steel pipes 10 placed on top of each other. When the steel pipe section has reached the repaired piping and the contemplated place of junction, earth and gravel are removed therefrom and the service line is connected. The temporary access well consisting of steel pipes 10 can thereafter be disassembled by successively withdrawing the steel pipes from the shaft. For carrying out the above method, the invention also relies on the heater 6 shown in Fig. 2. The heater consists of two semi-circular parts 12 and 13 which are interconnected by a hinge 11 and which, when brought together, define a central hole for allowing passage of the compressed-air hose 5 for powering the breaker head 3. The hose 5 is passed through said central hole with the heater halves 12, 13 parted. The boun¬ dary surface of the hole is suitably lined with a ceramic material. The heater 6 preferably consists of light metal, each half being cast in one block and has an electric heating coil integrated therein. On both sides of the heater, handles 14, 15 are pro¬ vided for greater ease to handling. Two boxes 16 and 17 hold components, such as thermostats or other control equipment, required for controlling the temperature in the heater halves. Electric supply cables are also connected to these boxes.

Claims: CLAIMS 1. A method for replacing damaged pipes, e.g. sewers, buried in the ground and extending between two shafts or access wells, lengths of a replacement pipe being descend¬ ed one after the other through one of said shafts, c h a- r a c t e r i z e d in that the pipe lengths (1) are descended in the shaft placed on a pressure medium hose (5) by means of which a breaker head (3) is powered for disintegrating the existing damaged pipe (B) while being pulled therethrough and entraining the first pipe length (1), that the pipe lengths are descended through the shaft to a position adjacent a previously descended pipe length, and that the end surfaces of the two pipe lengths are heated to a temperature in the vicinity of the melt¬ ing point and are welded together. 2. Method as claimed in claim 1, c h a r a c t e r ¬ i z e in that the breaker head (3) is pulled through the damaged pipe (B) by means of a wire (7) which is fixed to the breaker head and is winched through the other shaft. 3. A device for heating the end surfaces of pipe lengths (1) for carrying out the method as claimed in claim 1 or 2, c h a r a c t e r i z e d by two plate members (12, 13) which are interconnected by a hinge (11) and which, when brought together, form a heating plate (6) for heating the pipe end surfaces to be welded together, said heating plate (6) having a central hole (18) for allowing passage of the compressed-air hose (5). 4. Device as claimed in claim 3, c h a r a c t e r - i z e d in that the heating plate (6) is electrically heated. 5. Device as claimed in claim 4, c h a r a c t e r ¬ i z e d in that the hole (18) has a lining of ceramic material for protecting the compressed-air hose.

Inventors: CARLSSON KRISTER, MATTSSON BENGT, PERSSON RONNIE, CARLSSON, KRISTER, MATTSSON, BENGT, PERSSON, RONNIE
Applicants: MALVA I MALMOE UTVECKLINGS
Application year: 1987
Main classification: F16L55
IPC codes: B29C65, E21B7, E21B19, F16L55