Seal for a joint or juncture – Seal between fixed parts or static contact against... – Contact seal for a pipe – conduit – or cable
Reexamination Certificate
1999-10-08
2001-07-17
Mah, Chuck Y. (Department: 3626)
Seal for a joint or juncture
Seal between fixed parts or static contact against...
Contact seal for a pipe, conduit, or cable
C277S612000, C277S616000, C277S917000, C285S368000
Reexamination Certificate
active
06260854
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a flat gasket ring, in particular for arranging between two flange adapters in pipeline systems.
Transition connections are necessary when laying pipelines. These connections usually take place via moldings which are equipped with a flange adapter. In each case one flange is pushed over the molding which is to be connected, until said flange butts against a so-called welding collar. There are also moldings with an integrated flange. The sealing surfaces of the flange adapters of the two moldings which are to be connected to one another are brought into abutment with one another with the interposition of a flat gasket ring. The flanges are connected to one another by means of a plurality of screwed connections, in order for the seal, which is located between the sealing surfaces of the flange adapters, to be subjected to the contact pressure which is necessary for the fluid-tight connection. Flat gasket rings are used in the case of sealing surfaces without a groove.
A flat gasket ring usually has to be designed such that it covers at least the entire cross section of the sealing surface of the flange adapter, i.e. it extends from the internal diameter to the external diameter of the flange adapter. This should ensure a fluid-tight connection between two abutting moldings with a seal arranged between them. Since the flange encloses the gasket ring, the latter is difficult to position, and inaccurate centering and slipping during installation may lead to the gasket ring no longer covering the cross section of the sealing surface. This results in different pressures over the surface area in the sealing region, which in turn may result in leakage. It is thus often the case that, for example according to U.S. Pat. No. 5,472,214, extensions with openings are provided on gasket rings, the screws or assembly bolts of the flange connection being guided by way of said extensions and thus positioning the gasket ring in relation to the flange ring. In this case, the sizes of the flange screws, bolt-circle diameters and internal and external diameters of molding, flange adapter and flange, as well as other parameters, are defined by various standards which, with the exception of the internal diameter of the molding, are often not compatible with one another.
In particular in applications in high-purity pipeline systems, relatively accurate positioning of flat gasket rings is necessary since, otherwise, even extremely small gaps and openings in the region of the pipe/gasket-ring transition constitute undesired dead spaces. Such a transition has to be positively locking and smooth here, since uneven transitions cause turbulence in the flowing medium, which may have fluid-dynamic dead spaces.
Taking this prior art as the departure point, the object of the present invention is to propose a flat gasket ring which can be easily fixed in a predetermined position and is suitable for various standards. It should also be shaped and produced such that, once the necessary contact pressure has been applied, it produces a positively locking connection which has a smooth surface and does not have any dead spaces in relation to the medium in the interior of the pipe system.
SUMMARY OF THE INVENTION
This object is achieved by providing a flat gasket ring for producing a fluid-tight connection between two opposite moldings which are provided with flange adapters and have an internal diameter, through which the medium which is to be transported flows, and an external diameter, wherein flanges are pushed over the moldings and connected to one another by means of screws, to produce contact pressure on the gasket, wherein, in the outer circumferential region, the flat gasket ring has at least one lip structure which projects radially beyond the external diameter of the moldings and is designed for enclosing the moldings in an essentially positively locking manner. Further advantageous configurations can be gathered from the dependent claims.
The flat gasket ring according to the invention is distinguished in that it has self-centering structural elements. By virtue of a lip which is provided concentrically on both sides of the external diameter of the flat gasket ring, the flat gasket ring can be applied accurately over the surface of a standard ANSI Sygef flange. This lip may be severed in order to position the flat gasket ring in ISO/DIN Sygef flanges of larger diameters than those of the ANSI standard.
For this purpose there is located, over a relatively short section of a circle segment, a second lip structure which is arranged on a larger radius, corresponding to the ISO standard. Additional severing of this lip structure allows the flat gasket ring to be used as a conventional flat gasket ring, although this then has to be centered.
A slot-like cutout is arranged in a lateral extension in the region of the second lip structure. As a result, the flat gasket ring can be retained by an assembly bolt or screw during installation, thus preventing the flat gasket ring from dropping out.
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Bachman & LaPointe P.C.
Georg Fischer Rohleitungssysteme AG
Mah Chuck Y.
Patel Vishal
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