1. Field of the Invention
This invention relates to gaskets.
2. Discussion of the Related Art
Gaskets are widely used to prevent leaks from joints. Frequently, gaskets deteriorate with age and at some point begin to leak. Also, some fluids corrode some gasket materials, resulting in leaks. Some gaskets, such as those used to seal rocker arm covers to automotive engines, tend to lose resiliency and shrink with age, allowing engine oil to leak out onto the engine. Some types of gaskets must be tightened periodically to avoid leaks. Welding a joint might be a method of achieving a joint which does not leak, even after the passage of time. However, welding a joint to prevent leaks is usually not feasible, since almost all joints have portions which are inaccessible.
In order to obviate the disadvantages of the art, a gasket assembly for sealing a pair of mating surfaces to each other is provided. One embodiment has an electrically-conductive gasket base having positioned on opposite sides thereof a pair of rings or layers of an element selected from the group consisting of fusible alloys, synthetic thermoplastic materials, and brazing alloys. The rings or layers, which are preferably made of a material which will wet the surfaces when melted, are attached to the gasket base by the use of a thermoplastic synthetic material, by a fusible alloy applied at points around the gasket base, or by some mechanical means. However, it is preferred that these layers be coated onto the gasket base. In use, this embodiment is positioned between two surfaces to be sealed to each other, and the surfaces are held in close contact with the gasket assembly. An electrical current is then passed through the gasket base to heat the gasket base and melt the layers, causing the surfaces to seal to opposite sides of the gasket base.
Another embodiment of the present invention is especially suitable for sealing a pair of mating surfaces which are the bases of cylindrical members such as solid rods or tubes, especially pipes. This embodiment is an electrically-conductive sleeve or tube which surrounds the cylindrical members whose bases are to be joined and contacts their outer surfaces. The electrically-conductive sleeve has an inner surface which is coated with an element selected from the group consisting of fusible alloys, synthetic thermoplastic materials, and brazing alloys. When melted, these elements wet the outer surfaces of the cylindrical members whose bases are to be joined. In use, this embodiment surrounds and contacts the outer surfaces of two cylindrical members whose bases are the mating surfaces which are to be joined. An electrical current is then passed through the electrically-conductive sleeve to heat the sleeve and melt the element coating the inner surface of the sleeve, thereby effectively joining the two cylindrical members to each other at their bases and sealing them in place upon cooling of the melted element.