Hydraulic and earth engineering – Subterranean or submarine pipe or cable laying – retrieving,...
Patent
1993-02-02
1995-11-21
Corbin, David H.
Hydraulic and earth engineering
Subterranean or submarine pipe or cable laying, retrieving,...
405157, F16L 55165
Patent
active
054680913
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to inserting linings into pipes particularly, but not exclusively, to the insertion of a preformed lining into an underground gas service pipe extending from an underground gas main to a building.
The terms `lining` and `liner` are used herein to include any insert which is capable of conveying a fluid within the pipe, and the insert may or may not be a close fit in the pipe.
Gas service pipes were made of steel or copper and they can be subject to corrosion in the ground and then leak. A procedure has been devised and is widely used for lining such gas services with a plastics tube. The procedure involves excavating a hole in the road or pavement to expose the connection between the gas service and the gas main, removing the section of service adjacent to the connection, pushing a length of plastics tube through the remaining length of service, and effecting connections at opposite ends of the plastics tube respectively with the main and with a meter cock.
In order to stop gas, in the event of a fire, spreading along the service by way of the annular space between the external surface of the plastics tube and the internal surface of the old service, that annular space in the end region of the service adjacent to the meter is filled with a predetermined quantity of sealant material, sufficient to fill totally the vertical limb of the service to provide a half-hour fire resistance.
The present invention is aimed at avoiding the need in most cases to excavate a hole to expose the connection between the main and the service. Such holes are costly to produce and fill, and can be very inconvenient to the public.
Whilst the invention is primarily concerned with gas pipes, it might be applied to water pipes or pipes conveying other liquids.
SUMMARY OF THE INVENTION
According to one aspect of the invention, a method of lining a pipe which has an underground connection with a further pipe comprises inserting a tubular liner into the pipe from the free end opposite to the underground connection such that the liner extends adjacent to or through the connection, and effecting a seal with a sealing means between the liner and the pipe or, possibly, between the liner and the connection, so as to close-off the annular space defined between the liner and the pipe in the region adjacent to said connection, the sealing means being introduced into the pipe from the pipe end remote from the connection.
Thus, the liner can completely bypass any corroded portions of the pipe, and fluid cannot enter the annular space from the further pipe. Providing that an effective seal is made between the liner and the pipe in the region adjacent the connection, there is no need to expose the connection by excavating in the road or footpath.
The seal is preferably effected by a sealant which is inserted in a flowable condition into the annular space from adjacent the free end of the pipe, following insertion of the liner into the pipe.
It is important that substantially no sealant material enters the further pipe because the further pipe will usually be a main which supplies similar such pipes, and a partial or complete blockage of the main should be avoided.
Preferably sealant detection means is provided to detect when the sealant closely reaches the connection, to enable the injection of sealant into the annular space to be terminated.
The sealant detection means may comprise an electrical sensor means which is arranged in the liner adjacent the connection and produces an electrical signal when the sealant reaches or closely approaches the sensor means.
The electrical sensor means may be an electromagnetic or inductive type but it is preferably a capacitative sensor. Conveniently, one electrode of the capacitative sensor is provided by the metal pipe being lined, and the other electrode by an insert which is arranged to be temporarily located within the liner, at a location spaced along the pipe by a predetermined amount from the underground end thereof.
The insert is preferably carried
REFERENCES:
patent: 3294121 (1966-12-01), Powell et al.
Arnold Kevin E.
Baylis Keith
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