Seal for a joint or juncture – Seal between relatively movable parts – Relatively rotatable radially extending sealing face member
Patent
1995-07-07
1997-06-17
DePumpo, Daniel G.
Seal for a joint or juncture
Seal between relatively movable parts
Relatively rotatable radially extending sealing face member
277207A, 277236, F16J 906
Patent
active
056391005
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a highly elastic sealing element of metal, or metal gasket, for the static, radial sealing of junctions and joints and in particular of flanged couplings.
2. Discussion of the Related Art
Elastic metal gaskets are compressed between surfaces to be sealed--or mating surfaces--and are elastically deformed in the process. In the gasket, the deformation creates a sealing pressure which increases up to a given point as the deformation progresses. For sealing static connections one can basically distinguish between two types of sealing devices.
For one, there are gaskets which lie flush against radial mating surfaces of the components to be connected and which are pressed together by an axial force. This is generally accomplished by a screw-on coupling. In this approach, the force of the screw-on action must be greater than the sum of the counterpressure force resulting from the internal pressure and the sealing force generated by the sealing pressure of the gasket. The integrity of the seal over time is a function of the gasket material used, the thermal expansion or the yield strain of the material or the tractive or compressive stress acting on the coupling for instance as a result of changes in the power applied in screwing the coupling together and thus in the compression force.
Then there are gaskets which lie flush against axial mating surfaces of two components to be connected and which are radially compressed between the latter. In this case the screw connection absorbs only the force of the internal pressure while the radial sealing force for the compression of the gasket is provided by the connecting hardware of the two components and is therefore basically independent of the axial connective force.
The state of the art has provided a multitude of gaskets suitable for either sealing method.
Nevertheless, as requirements become ever more demanding, the choice of sealing materials that lend themselves to the production of gaskets exposed to significant pressure differences or strong temperature fluctuations begins to dwindle rapidly and is often limited to metals.
A metal gasket usually consists of a material that is more easily deformable than that of the mating surfaces to be sealed. However, when pressed into position the gasket, while adapting to the shape of the mating surfaces, cannot compensate for major surface irregularities nor for additional deformative forces acting on the gasket since the deformability of a metal gasket is generally quite limited. This means that the use of metal gaskets is contingent on high surface quality of the mating surfaces and high precision in the geometry of the components.
For axial sealing purposes there exist more or less flexible metal gaskets which are adequate for meeting the aforementioned requirements. For example, there are flat dual-ring gaskets for axial sealing, such as those shown in Busak+Luyken's "Helicoflex" catalog, vol. 2/85, pages 8, 9, 10 and 18. Among the drawbacks of this design, besides the aforementioned, significantly greater screw-on connective force required to obtain a tight seal, is the danger of damage to the mating surfaces due to the frontal arrangement of the mating surfaces at the end of a component where, during handling, they are exposed to all kinds of mechanical impact.
For radial sealing purposes there have been flexible metal gaskets the installation of which requires a reasonable amount of force for deforming the metal gasket. The radial mating surfaces are relatively well protected against mechanical impact and the attainable integrity of the seal is not affected by the power applied in screwing the components together nor by variations in the connective force.
For example, DE-C-22 41 273 shows in its FIG. 5 a metal gasket for radial sealing in which the gasket, as it is being pressed in place, is radially deformed by the cone-shaped element preceding the mating surface of a component and is forced against the companion component. DE-C-37 13 0
REFERENCES:
patent: 3879043 (1975-04-01), Tozer
patent: 4194749 (1980-03-01), Benafons
patent: 4195885 (1980-04-01), van Haren et al.
patent: 4218067 (1980-08-01), Halling
patent: 4369980 (1983-01-01), Backlin
patent: 4457523 (1984-07-01), Hallling et al.
patent: 4477057 (1984-10-01), Friess
patent: 4603892 (1986-08-01), Abbes et al.
patent: 5201534 (1993-04-01), Miyaoh
patent: 5433456 (1995-07-01), Nicholson
"Helicoflex" Catalogue, vol. 2/85.
Garrigues Jean-Claude
Laulhe Rene
DePumpo Daniel G.
KSB Aktiengesellschaft
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