Pipes and tubular conduits – Repairing – Patches
Reexamination Certificate
2000-07-12
2001-05-29
Hook, James (Department: 3752)
Pipes and tubular conduits
Repairing
Patches
C138S098000, C138S092000, C138S162000
Reexamination Certificate
active
06237640
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention pertains to apparatus related to the repair of live mains lines. More specifically it pertains to variable length repair fitting for use in repairing or reinforcing polyethylene pipelines.
Fluid pipelines were mainly constructed of steel or even cast steel, and were subject to severe corrosion problems as they were buried underground. With the event of plastics, broader usage of different types of elastomeric materials has found favor with the gas pipeline industry. Thus, it is very common for gas pipelines to be constructed entirely out of plastics, especially polyethylene, since such pipelines exhibit excellent corrosion resistance.
However, many of the problems associated with the steel pipelines still occur with the plastic pipelines. For example, uncovering pipelines requires digging the earth around the line, sometimes leading to heavy equipment operators to severely scratch or even rupture the lines. Repairing plastic pipelines requires either spot repairing with traditional clamp and bladder techniques, or by cutting and replacement of the damaged section. It is therefore an object of the present invention to provide an improved method and apparatus for repairing a damaged polyethylene pipeline where the line does not require physical cutting and replacement of the damaged or weakened section.
SUMMARY OF THE INVENTION
The present invention provides a repair fitting apparatus that can be applied to a damaged or weakened carrier pipeline so as to entirely encapsulate the pipeline in the event of a ruptured pipeline, or to partially encapsulate it when the pipeline has been weakened, most likely through severe gouging or scratching.
In one embodiment, the repair fitting comprises three components; a midsection encapsulating piece for entirely enveloping the pipeline, and two connecting end pieces, which also entirely encapsulate the pipeline. The encapsulating midsection piece has male and female connector components at alternate ends thereof which allow additional sections to be added in the event one section is not long enough to cover the damage. The end pieces each have complementary male or female connector components on one respective end thereof which functionally slides into the encapsulating piece to form the fitting. The other ends of each end piece are constructed to closely contact the outer surface of the carrier pipe, while the end provided with the connector is constructed so as not to contact the outer surface but rather to create an annular interior space between the end piece and pipelines. Likewise, because the encapsulating piece attaches to the end of the pieces where the annular space is formed, the encapsulating section envelopes the carrier pipeline but does not rest in close contact against it.
In another embodiment, these components are again used, but rather than a male into female connection, there is a stepped connector construction with overlapping inside and outside contact points.
Internal heating wires are disposed in the wall thickness and male connector components of all three components of the fitting. When supplied with an electrical source, the wires cause the components to melt along connection points there between and to melt the ends of each end piece which is in close contact against the pipeline, thereby sealing the fitting to the pipelines. In this way, a portal provided on the midsection piece can be used to established communication between the pipeline interior and atmosphere, actually allowing a gas escape route. However, the portal is sealable and prior to sealing, the gas purges all entrapped air from the fitting interior so that gas/air mixture explosion limits will have been reached and surpassed during purging.
In the case of the stepped connector construction of the inside and outside contact points, heating wires are disposed proximate the inside contact points.
In a second embodiment more specific to reinforcing a gouged or scratched pipeline, the three components are in full contact against the pipeline outside surface. Electric supply to internally embedded heating wires causes the connection points between the pieces to melt together, as well as the entire perimeter of the fitting to melt in place against the pipeline.
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Hook James
Nicor Technologies
Orum & Roth
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