Seal for a joint or juncture – Process of static sealing – Pipe – conduit – or cable
Reexamination Certificate
2001-02-07
2002-06-18
Knight, Anthony (Department: 3626)
Seal for a joint or juncture
Process of static sealing
Pipe, conduit, or cable
C277S606000, C277S607000, C277S616000
Reexamination Certificate
active
06406025
ABSTRACT:
BACKGROUND
The present invention relates to gaskets for use in providing a liquid-tight seal between an opening in a sidewalk and a pipe and more particularly to a gasket for providing an excellent liquid-tight seal with a corrugated pipe and which is easy to install and use.
SUMMARY
Gaskets have been typically utilized for providing a liquid-tight seal between a sidewalk opening, for example, an opening provided in a cast member employed in septic, storm water or waste water systems, and a pipe extending into the opening.
Such gaskets are typically resilient, annular-shaped, rubber or rubber-like members having an embedment portion which is embedded in the sidewalk opening of a cast member when the member having the sidewalk opening is cast, and a pipe engaging portion for surrounding and engaging the outer periphery of the pipe. Alternatively the gasket may be placed in an opening which is cored or otherwise formed in a cast member, the gasket having a portion extending into the formed opening and held therein by means of an expansion type clamping band. This type of mounting of a gasket in an opening in a cast member is referred to as being “jacked-in” an opening.
A liquid-tight seal is provided by causing the pipe engaging portion of the gasket to undergo stretching when the pipe is pushed through the gasket or, alternatively, the liquid-tight seal is obtained by placing a clamping band about the pipe engaging portion so as not to rely exclusively upon the stretched gasket absent a clamping band for a liquid-tight seal.
All gaskets presently available provide an adequate liquid-tight seal with cylindrical pipe having a smooth outer periphery. However, pipe having an undulating periphery presents unique problems making it difficult to obtain an adequate liquid-tight seal employing presently available gaskets.
Pipe having a smooth, cylindrical-shaped outer periphery, and typically cast from concrete, are rapidly being replaced for use in underground sewage systems and the like by plastic pipe, which provides more than adequate structural strength while significantly reducing the cost and weight of such pipe as compared with concrete pipe, thereby significantly reducing fabrication, handling, transportation and installation costs.
To obtain plastic pipe of the desired structural strength, some plastic pipe is formed to have a corrugated outer-peripheral shape defined by alternating, annular shaped recesses and projections each recess and projection having a substantially U-shaped cross-section. The interior of the pipe is provided with a smooth, cylindrical-shaped inner periphery integrally joined to the base of each annular recess, which pipe structure yields a pipe of light weight and get significantly large structural strength.
Corrugated pipe of the type described here in above, due to their method off fabrication, are often provided with vent tubes which project radially outward and into each annular recess, said projections lying along an imaginary line parallel to a longitudinal central axis of the pipe at “12 o'clock and “6 o'clock” and extending in an outward radial direction from the cylindrical interior portion.
In order to provide a water-tight seal, the pipe engaging portion of the gasket encircles and engages the outer periphery of the corrugated pipe. Due to the configuration of the corrugated pipe, it is impractical, if not impossible, to obtain a water-tight seal employing only a resilient gasket, i.e., employing a gasket absent a clamping band.
One technique for providing a water-tight seal is to mount a pipe adapter upon the corrugated pipe by stretching the pipe adapter until it is positioned in the proper location, encircling one of the annular projections. The end of the gasket to be water-tightly sealed to the pipe is then pulled over the adapter. A clamping band is placed over the gasket and then tightened. Placement of the take down clamp is critical, if it is not placed properly, failure can occur, in particular if the clamp straddles the pipe and adapter, unequal compression can be the result.
This design has the disadvantage of providing rubber to rubber contact between the adapter and the gasket causing undesirable kinking when the clamping band is tightened which ultimately results in the failure to provide a water-tight seal. In addition, the installation is both tedious and complicated, due to the necessity of significant exertion for stretching the adapter or, to state it in another way, it is tedious and difficult to mount the adapter and push the corrugated pipe through the gasket.
It is therefore desirable to provide a gasket and clamping assembly which is easy to apply, especially one capable of insertion of the corrugated pipe into the gasket without undue exertion yet one which provides an excellent liquid-tight seal between the corrugated pipe and the gasket.
The present invention is characterized by comprising, in one embodiment thereof, a gasket having an inner diameter which is greater than the outer diameter of the corrugated pipe to facilitate easy insertion of the corrugated pipe into the gasket without any exertion whatsoever.
The gasket, in one embodiment, is provided with an which is embedment portion embedded into the cast member during the casting operation and having an annular pipe engaging portion connected to the embedment portion by an annular curved or “radius” portion. The gasket, in another embodiment, is modified so that the portion inserted into periphery of and engaging at a previously formed opening in a cast member has no embedment portion, and in place thereof, is provided with a substantially cylindrical-shaped outer surface for engaging the opening and an inner periphery provided with an annular recess for receiving and aligning an expansion-type clamping band which is expanded in circumference to press the opening engaging portion into firm, liquid-tight engagement with the opening into the cast member. The gasket is placed under compression between the expansion type clamping band and the opening in the cast member sufficient to retain the liquid-tight seal.
The pipe engaging portion is provided with a pair of integral projections about the outer periphery thereof, defining a recess for receiving and aligning a clamping band.
In one embodiment, the recess receiving the clamping band is positioned about an annual recess in the corrugated pipe. The clamping band, when tightened, has a width which is selected to cause the pipe engaging portion of the gasket to form an excellent liquid-tight seal with opposite sides of the annular recess while at the same time being prevented from reaching and engaging the base of the annular recess to prevent engagement of the gasket with a possible vent tube projection formed in the corrugated pipe during fabrication thereof.
In one preferred embodiment, the outer periphery of the pipe engaging portion is provided with integral, spaced parallel projections which define an annular recess for receiving and positioning an adjustable clamping band. The clamping band has a width relative to an annular recess within the corrugated pipe designed to urge the pipe engaging portion into the annular recess and to form a liquid-tight seal between opposite annular sides of the clamping band and the pipe engaging portion which is urged against opposite tapering sides of the annular recess. The adjustable clamping band is tightened sufficiently to assure a liquid-tight seal while preventing the gasket from engaging the base of the annular recess to prevent the portion of the gasket within the annular recess from forming an irregular shape and kinking which would otherwise diminish the assurance of a liquid-tight seal.
The pipe engaging portion which is urged into the annular recess cooperates with the annular recess to form an annular pocket which acts to further enhance the liquid-tight seal as a result of the air compressed within this annular pocket.
The clamping band may assume any one of a variety of different designs including one in which the clamping band is of the type ha
Andrick William C.
Kelly James A.
Westhoff James A.
Beres John L.
Knight Anthony
Poly-Tec Products, Inc.
Volpe and Koenig P.C.
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