Pipes and tubular conduits – Repairing – Patches
Reexamination Certificate
1999-04-22
2001-06-05
Hook, James (Department: 3752)
Pipes and tubular conduits
Repairing
Patches
C138S097000, C029S402090, C405S150100
Reexamination Certificate
active
06240965
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is related primarily to an apparatus, method, and sealing device for repairing pipes and conduits, particularly high temperature, high pressure pipes and conduits, such as steam lines. More particularly, the invention is directed to an internal repair of a section of damaged, weakened, or leaking pipe or conduit, in which the section to be repaired is typically located in an inaccessible area, such as underground.
2. Background and Material Information
Conduit systems for conveying natural gas, water, and steam are typically located underground and, in general, are not easily accessible if repair or other maintenance is required after installation. Over a period of time, such conduit systems can become damaged, weakened, or can otherwise begin to leak, particularly at the joints between adjacent conduit sections, but also longitudinally along sections of the conduit. Thus, there can be a problem of ex-filtration of gas, water or steam from the damaged conduit sections.
Furthermore, in the repair of high temperature, high pressure pipes and conduits, such as steam lines, which are utilized by utility companies, there is usually a need to effect the repairs in as short a time period as possible. Thus, there is a need to effect high strength repairs to such high temperature, high pressure pipes and conduits quickly so that the utility lines can be returned to service in a relatively short period of time, such as less than one day.
Additional problems associated with similar systems, and a number of previous repair methods and apparatuses are disclosed, for example, in U.S. Pat. Nos. 5,119,862 and 5,351,720. These patents, which disclose “No-Dig” or non-excavation repairs, utilize a sleeve or liner which is transported to the site of the weakened or damaged pipe in a coiled or partially coiled configuration. Once the repair liner is located in the necessary position at the site of the repair, internal pressure is applied to the sleeve by means of an inflatable bladder or other means, which causes the sleeve to begin to uncoil and expand in the direction of the “host” pipe to be repaired. The sleeve, which includes a gasket or sealing compound on its outer surface, reaches a slight over-expanded condition, whereby the liner compresses the gasket or sealing compound against the inner surface of the host pipe. The internal pressure is then reduced or removed and the sleeve is slightly recoiled, whereby overlapping edges of the sleeve become locked in place by virtue of complementary locking devices.
The methods and apparatus disclosed in the aforementioned patents are intended primarily for the repair of conduits that carry wastewater and other fluids that are not in an over-pressure environment. However, a high temperature, high pressure pipe, such as a steam line, also requires periodic repair, particularly for sealing against ex-filtration, i.e., against a leak of the high temperature, high pressure fluid, such as steam, from the inside to the outside of the pipe.
The methods and apparatus disclosed in the aforementioned patents are useful for the repair of moderately high pressure pipes or conduits, although a particular problem, explained below, is posed. The size of these pipes is typically between 4 inches and 36 inches in diameter or even greater. Unlike an elastic compressible gasket or a polyurethane foam, e.g., which are usable for the repairs described in U.S. Pat. No. 5,351,720, high temperature, high pressure pipes and conduits may not be suitable for use with compressible gaskets, foam sealants, or epoxy resins or other curable, non-expansible sealants that are typically used in the prior art methods because the high temperatures and the moisture in the steam may degrade such sealants, breaking them down, and causing them to fail. Thus, the high temperature, high pressure fluid conveyed within the conduit may ex-filtrate through the degraded sealant, or the pressure of the fluid may cause the repair sleeve to fracture in the area of the repair which would also allow the fluid to ex-filtrate through the repaired section.
SUMMARY OF THE INVENTION
One aspect of the present invention is to provide for an apparatus, method, and sealing device for repairing high temperature and high pressure pipes and conduits, when a compressible gasket, foam sealant, epoxy or other curable, non-expansible sealant is not suitable to be utilized in the repair.
More particularly, another aspect of the present invention is to provide for the repair of high temperature, high pressure pipes and conduits with a malleable repair sleeve that is pressed or hammered into tight engagement with the inner wall of the pipe or conduit to be repaired to create a seal which prevents ex-filtration.
According to another aspect of the present invention, a conduit repair apparatus is provided that includes a carriage constructed and arranged for movement within a conduit in which repairs are to be effected, the carriage including a carrying frame and a drive member. The apparatus also includes an expansion and brake mechanism provided on the carriage, the expansion and brake mechanism including at least one radially movable engagement member operatively mounted to apply a radially outwardly directed force. A force applicator mechanism is provided on the carriage, and the force applicator mechanism includes at least one radially movable pressure member operatively mounted to apply radially outwardly directed pressure and for rotation about an axis of rotation generally coincident with a central longitudinal axis of the conduit in which repairs are to be effected.
A power source is operatively connected to force applicator mechanism to rotatably drive the at least one pressure member about the axis of rotation, whereby a repair sleeve positionable within the conduit can be radially expanded by the expansion and brake mechanism into engagement with an inner wall of the conduit, the expansion and brake mechanism can be positioned at a location outside the repair sleeve and radially expanded to engage the inner wall of the conduit to hold the carriage fixed relative to the conduit, and the force applicator mechanism can be operated to radially actuate the at least one radially movable pressure member and simultaneously to rotate the at least one pressure member about the axis of rotation to thereby apply radially outwardly directed pressure uniformly to an inner wall of the repair sleeve. Thus, the conduit repair apparatus of the present invention permits rapid repair of high temperature, high pressure conduits, such as steam pipes, without requiring excavation at the site of the repair.
In another aspect of the present invention, the expansion and brake mechanism of the conduit repair apparatus includes a plurality of radially movable engagement members, and the engagement members are generally uniformly radially spaced about a central axis. Furthermore, the at least one engagement member may be operatively connected to the carriage by at least one of an hydraulic actuator, a pneumatic actuator, and a mechanical actuator which effects radial outward movement of the at least one engagement member. Additionally, the at least one radially movable pressure member may be operatively connected to the carriage by at least one of an hydraulic actuator, a pneumatic actuator, and a mechanical actuator which effects radial outward movement of the pressure member to apply the radially outwardly directed pressure, which thereby expands and deforms the repair sleeve into tight engagement with the conduit inner wall to form an effective seal.
In other aspects of the present invention, the at least one radially movable pressure member of the conduit repair apparatus may include a hammering applicator for applying repeated hammering strokes to the inner wall of the repair sleeve, or the at least one radially movable pressure member may include a rolling applicator for applying a spinning force application to the inner wall of the repair sleeve. Additionall
Greenblum & Bernstein P.L.C.
Hook James
Link-Pipe (H.K.), Ltd.
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