Hydraulic and earth engineering – Subterranean or submarine pipe or cable laying – retrieving,...
Patent
1996-04-02
1998-05-19
Graysay, Tamara L.
Hydraulic and earth engineering
Subterranean or submarine pipe or cable laying, retrieving,...
405303, 138 97, F16L 55165
Patent
active
057527865
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method for relining an underground branch conduit of an underground main conduit by a relining pipe being inserted into the branch conduit and brought to tight engagement with the main conduit.
Damaged or leaky pipelines can be relined in several ways but especially preferred are methods in which a relining pipe is inserted into the damaged pipeline. The advantage of these methods is that extensive excavation and digging work can be avoided since the work mainly can be performed from existing manholes. Prolonged interruptions in industrial areas as well as traffic diversions can thereby be avoided.
One method for relining pipeline systems with branch conduits comprises relining first of the main conduit and then of the branch conduit a tight connection then being accomplished between the main conduit and the branch conduit.
According to U.S. Pat. No. 4,029,428 relining of the branch conduit is accomplished after relining of the main conduit, by the relining pipe being pushed into the branch conduit from the upstream end thereof, i.e. the end opposite to the end connected to the main conduit. Then a tight connection is formed between the relined main conduit and the relined branch conduit by introduction of polyurethane foam via the branch conduit, which is allowed to set in the junction area, and a connection passage is cut between the main conduit and the branch conduit from the branch conduit at the junction site.
According to GB-A-2,326,158 relining of the branch conduit is accomplished by a relining pipe being pushed into the branch conduit from the upstream end thereof a sealing element a being provided at the front end of the relining pipe. The sealing element is pushed into the main conduit then to be drawn back into the branch conduit to a sealing position at the junction site thereof. A sealant is then injected between the branch conduit and its relining pipe.
However, these methods involve a practical drawback when the relining of the branch conduit takes place from the upstream end thereof by pushing the relining pipe into the branch conduit since the upstream end seldom has a man-hole but often has a covering on a vertical riser. From here it is almost impossible to install relining pipes without destructive measures. Therefore, relining from the upstream end can be difficult to accomplish and furthermore complicates sealing of the junction between the main conduit and branch conduits. Also, high the axial flexibility of the relining pipeis requiredwhen the inner diameter of the main conduit is small;, it may be as small as 170 mm.
Other methods for relining branch conduits, e g according to GB-A-2,213,230, involve the introduction of a relining pipe with a deformed cross section. This requires processing of the pipe in order to deform it before as well as after the insertion thereof so that the pipe can regain its circular cross sectional shape after insertion. According to additional methods a stocking-shaped element is pulled into the pipe, which is hardened after a circular cross sectional shape having been imparted to it, a process which is complicated. Both these methods are very expensive.
According to EP-A1-0,487,179 and GB-A-2,041,147 a flexible hose having a flange is introduced into a branch conduit via a main conduit by means of a rope or the like, the flange being brought into sealing engagement against the inside of the main conduit and the inside of a relining pipe in the main conduit, respectively.
A flexible hose is a cylindrical body which is essentially unable to take up radial compressive forces as well as axial bending forces. Thus, it is not suitable to install a hose in for example a sewer, which is the main application of the present application, considering the forces which must be taken up by the hose, such as earth loads and groundwater pressure. This is particulary true when the conduit in which the relining pipe has been inserted is defect and cracked or has even ruptured into several pieces due to external forces.
EP-A1-0,213,674 disclose
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patent: 4754781 (1988-07-01), Jan de Putter
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patent: 4954016 (1990-09-01), Storgard
patent: 4958959 (1990-09-01), St Onge
patent: 5040922 (1991-08-01), Himmler
patent: 5253956 (1993-10-01), Fisco et al.
patent: 5297582 (1994-03-01), Kitajima et al.
patent: 5632952 (1997-05-01), Mandich
Graysay Tamara L.
Lagman Frederick L.
Uponor Innovation AB
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